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WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
1
Master Thesis
The clinical performance of the DAVID-system for the
in vivo verification of VMAT irradiation
Presented by Mustafa Saibu Danpullo
1st supervisor
Prof DrBPoppe
2nd supervisor
Dr HK Looe
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg2
Layout
I Introduction
II Theory
VMAT and IMRT
MLC Design and Agility
MWPC and DAVID system
III Materials amp Methods
Equipment alignment patient data stability of DAVID chamber
Beam property Error detection
Deconvolution
DAVID QA software
IV Results Discussion
V Conclusion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg3
I Introduction
IMRT (Intensity-modulated radiation therapy)
VMAT (Volumetric Modulated Arc Therapy)
Why In vivo verification
ICRU report 24 (1976) recommended that certain types of tumors
requires improve accuracy from 5 to 35
To detect Equipment-related errors and deviations from the initial plan
Complexity of planning and delivery techniques increases risk for
treatment-related error incidents
In 1992 to 2007 more than 4000 near misses without adverse
outcome to patientrsquos case were reported more than 50 were related
to the planning or treatment delivery stage
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg4
In vivo dosimetry methods
in vivo intracavitary dosimetry with TLD
Diodes
DAVID (Device for Advanced Verification of IMRT deliveries
In-vivo verification during treatment
Online measurement of differences in dose to reference
Error detection of the Multi Leaf Collimator (MLC)
I Introduction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
5
II Theory
Mostly Siemens Elekta and Varian have introduced new LINAC
control systems that will be able to change the MLC leaf positions
IMRT uses many small fields to generated by beam-shaping
devices (MLC) to deliver a single dose of radiation
IMRT Intensity-modulated Radiation Therapie
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg6
II TheoryVMAT Volumetric Modulated Arc Therapy
VMAT is a rotational IMRT that can be delivered using
conventional LINAC with MLC
Elekta and Varian have introduced new LINAC control systems
that will be able to change the MLC leaf positions and dose rate
while the gantry is rotating
Precise Beam infinity and Rapid Arc
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg7
A schematic drawing of the Siemens type A Elekta type B and Varian type C MLC [18]
Stepped leafs for different manufacturers [34]
II Theory
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg8
II Theory Agility MLC design
bull 160 tungsten leafs
bull rounded arc edge
bull 5 mm width
bull High speed(2x normal MLC) of up to
3cmsec
bull large field MLC enable clinicians to
shape radiation
bull extremely low transmission of about
lt05
bull 45 cm isocenter clearance from
accessory holder
MLC Motor
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg9
Inventor
Prof Georges Charpak
France1968
Nobel Prize in Physics (1992)
II Theory Multi wire proportional chamber (MWPC)
The DAVID chamber is a multi-wire
ionization chamber designed by PTW
Freiburg based on Charparks multi wire
proportional chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg10
Compton scattering Electric field causes electrons move to the
anode(wire) and ionizied atomsmolecules to the
cathode(plate)
Each detection wire accumulates charge which
loads a C
After the voltage at the capacitor is read out it is set
to zero and charged again
The voltage achieved is read out by the associated
amplifier at a rate of 1 Hz
Performed by multi-channel electrometer
(MULTIDOS) + additional Software
II Theory DAVID system functioning principle
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
11
Signal interpretation
Ri reading of a single channel (ion charge collected)
C cross section of the lengthy collection volume along the wire
Ii ionization density (x1 start of wire x2 end of wire)
li1-li2 aperture of the associated leave pair
II Theory
II Theory
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
12
Front Plate
Back Plate
Air Volume
II Theory DAVID system signal recording
3 groups of secondary electrons contributing to the signala)ldquoprimary signalrdquo
b)scattered signal
c)leakage radiation
(background signal)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg13
VMAT Planning
Treatment Planning System ONCENTRA Masterplan Version 43
ELEKTA Synergy accelerator with an Agility 80 leaf-pair MLC
bull Desktop Pro TM 7011 is Elektas third generation fully integrated
digital control system MOSAIQ DAVID software version 20
DAVID T34065
III Materials and Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg14
Patient data configuration chart
III Materials amp Methods
Reference
1st session
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg15
DAVID Analysis
bull PTW DAVID 20 software
III Materials amp Methods
Warning level 3
Alarm level 5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg16
III Materials amp Methods
bullVMAT 4 (1 HampN 3 Prostates)
bull180deg to -180deg Clockwise and anti clockwise
Stability of the DAVID system
bullIMRT 1 (Prostate)
bull0deg
bull90deg
bull270deg
(Prostate and Head and Neck) 14 days
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg17
III Materials amp MethodsThe beam property of the DAVID chamber
bullPercentage depth dose (PDD)
bullRoos chamber 34001
bullMP3 water phantom
bullTransmission factor for 6 and 15 MV
bullSemifex T31010 (Diff Field sizes)
Setup conditions
bull With and without DAVID
bull SSD 100 and 80 cm
bull Photon energy 6 and 15
MV
bull Different field sizes
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg18
1 Successive opening of 1 leaf on 1
side
III Materials amp MethodsVMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg19
1 Successive opening of 1 leaf on 1
side
VMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
III Materials amp Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg20
DeconvolutionIII Materials amp Methods
S(x) measured signal as convolution of
P(x) True bdquodoseldquo profile with
LRF fɛ(x)
S(x) = P(x) f(x)
bdquovan Cittertldquo iterative deconvolution
algorithm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg21
opened MLC at every 10th interval from 1st to 80th
pairs
Nine MLC slit through the entire DAVID chamber
IV Results and Discussion Alignment
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg22
IV Results and Discussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT prostate
bull Deviation of plusmn1 (-1)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg23
IV ResultsDiscussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT HampN
bull Deviation of lt05
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg24
IV ResultsDiscussion Transmission factor
The average KDAVID
bull 0939 plusmn0003 for 6 MV
and
bull 0953 plusmn 0004 for 15 MV
Reduction of dose at isocenter
due to 8mm of PMMA
By measuring the attenuation
factor the output value can be
corrected
Attenuation of the beam by the DAVID chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg25
100 cm SSDIncreased about
032 with DAVID
No change of
Dmax
14 cm with
and without DAVID
80 cm SSD
An increased about
426 with DAVID
slight change of
Dmax
13 cm with DAVID
14 cm without DAVID
IV ResultsDiscussion Changes in PDD
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg26
100 cm SSD
An increased about
067 with DAVID
Dmax
26 cm No change
80 cm SSD
An increased about
18 with DAVID
slight change of
Dmax
18 cm with DAVID
24 cm without DAVID
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg27
Surface dose
Increase with increase in field size
Increase with increase in energy
Increase with decrease in SSD
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg28
Pronounce with
decrease in SSD and
increase in photon energy and
increase in field size
Increase in surface dose is
due to scattered secondary
electrons from the DAVID
chamber reaching the
water phantom surface
(electron contamination)
6 cm
45 cm
100 cm
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg29
Deconvolution test
by iteration method
IV ResultsDiscussion Deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg2
Layout
I Introduction
II Theory
VMAT and IMRT
MLC Design and Agility
MWPC and DAVID system
III Materials amp Methods
Equipment alignment patient data stability of DAVID chamber
Beam property Error detection
Deconvolution
DAVID QA software
IV Results Discussion
V Conclusion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg3
I Introduction
IMRT (Intensity-modulated radiation therapy)
VMAT (Volumetric Modulated Arc Therapy)
Why In vivo verification
ICRU report 24 (1976) recommended that certain types of tumors
requires improve accuracy from 5 to 35
To detect Equipment-related errors and deviations from the initial plan
Complexity of planning and delivery techniques increases risk for
treatment-related error incidents
In 1992 to 2007 more than 4000 near misses without adverse
outcome to patientrsquos case were reported more than 50 were related
to the planning or treatment delivery stage
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg4
In vivo dosimetry methods
in vivo intracavitary dosimetry with TLD
Diodes
DAVID (Device for Advanced Verification of IMRT deliveries
In-vivo verification during treatment
Online measurement of differences in dose to reference
Error detection of the Multi Leaf Collimator (MLC)
I Introduction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
5
II Theory
Mostly Siemens Elekta and Varian have introduced new LINAC
control systems that will be able to change the MLC leaf positions
IMRT uses many small fields to generated by beam-shaping
devices (MLC) to deliver a single dose of radiation
IMRT Intensity-modulated Radiation Therapie
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg6
II TheoryVMAT Volumetric Modulated Arc Therapy
VMAT is a rotational IMRT that can be delivered using
conventional LINAC with MLC
Elekta and Varian have introduced new LINAC control systems
that will be able to change the MLC leaf positions and dose rate
while the gantry is rotating
Precise Beam infinity and Rapid Arc
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg7
A schematic drawing of the Siemens type A Elekta type B and Varian type C MLC [18]
Stepped leafs for different manufacturers [34]
II Theory
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg8
II Theory Agility MLC design
bull 160 tungsten leafs
bull rounded arc edge
bull 5 mm width
bull High speed(2x normal MLC) of up to
3cmsec
bull large field MLC enable clinicians to
shape radiation
bull extremely low transmission of about
lt05
bull 45 cm isocenter clearance from
accessory holder
MLC Motor
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg9
Inventor
Prof Georges Charpak
France1968
Nobel Prize in Physics (1992)
II Theory Multi wire proportional chamber (MWPC)
The DAVID chamber is a multi-wire
ionization chamber designed by PTW
Freiburg based on Charparks multi wire
proportional chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg10
Compton scattering Electric field causes electrons move to the
anode(wire) and ionizied atomsmolecules to the
cathode(plate)
Each detection wire accumulates charge which
loads a C
After the voltage at the capacitor is read out it is set
to zero and charged again
The voltage achieved is read out by the associated
amplifier at a rate of 1 Hz
Performed by multi-channel electrometer
(MULTIDOS) + additional Software
II Theory DAVID system functioning principle
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
11
Signal interpretation
Ri reading of a single channel (ion charge collected)
C cross section of the lengthy collection volume along the wire
Ii ionization density (x1 start of wire x2 end of wire)
li1-li2 aperture of the associated leave pair
II Theory
II Theory
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
12
Front Plate
Back Plate
Air Volume
II Theory DAVID system signal recording
3 groups of secondary electrons contributing to the signala)ldquoprimary signalrdquo
b)scattered signal
c)leakage radiation
(background signal)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg13
VMAT Planning
Treatment Planning System ONCENTRA Masterplan Version 43
ELEKTA Synergy accelerator with an Agility 80 leaf-pair MLC
bull Desktop Pro TM 7011 is Elektas third generation fully integrated
digital control system MOSAIQ DAVID software version 20
DAVID T34065
III Materials and Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg14
Patient data configuration chart
III Materials amp Methods
Reference
1st session
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg15
DAVID Analysis
bull PTW DAVID 20 software
III Materials amp Methods
Warning level 3
Alarm level 5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg16
III Materials amp Methods
bullVMAT 4 (1 HampN 3 Prostates)
bull180deg to -180deg Clockwise and anti clockwise
Stability of the DAVID system
bullIMRT 1 (Prostate)
bull0deg
bull90deg
bull270deg
(Prostate and Head and Neck) 14 days
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg17
III Materials amp MethodsThe beam property of the DAVID chamber
bullPercentage depth dose (PDD)
bullRoos chamber 34001
bullMP3 water phantom
bullTransmission factor for 6 and 15 MV
bullSemifex T31010 (Diff Field sizes)
Setup conditions
bull With and without DAVID
bull SSD 100 and 80 cm
bull Photon energy 6 and 15
MV
bull Different field sizes
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg18
1 Successive opening of 1 leaf on 1
side
III Materials amp MethodsVMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg19
1 Successive opening of 1 leaf on 1
side
VMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
III Materials amp Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg20
DeconvolutionIII Materials amp Methods
S(x) measured signal as convolution of
P(x) True bdquodoseldquo profile with
LRF fɛ(x)
S(x) = P(x) f(x)
bdquovan Cittertldquo iterative deconvolution
algorithm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg21
opened MLC at every 10th interval from 1st to 80th
pairs
Nine MLC slit through the entire DAVID chamber
IV Results and Discussion Alignment
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg22
IV Results and Discussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT prostate
bull Deviation of plusmn1 (-1)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg23
IV ResultsDiscussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT HampN
bull Deviation of lt05
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg24
IV ResultsDiscussion Transmission factor
The average KDAVID
bull 0939 plusmn0003 for 6 MV
and
bull 0953 plusmn 0004 for 15 MV
Reduction of dose at isocenter
due to 8mm of PMMA
By measuring the attenuation
factor the output value can be
corrected
Attenuation of the beam by the DAVID chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg25
100 cm SSDIncreased about
032 with DAVID
No change of
Dmax
14 cm with
and without DAVID
80 cm SSD
An increased about
426 with DAVID
slight change of
Dmax
13 cm with DAVID
14 cm without DAVID
IV ResultsDiscussion Changes in PDD
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg26
100 cm SSD
An increased about
067 with DAVID
Dmax
26 cm No change
80 cm SSD
An increased about
18 with DAVID
slight change of
Dmax
18 cm with DAVID
24 cm without DAVID
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg27
Surface dose
Increase with increase in field size
Increase with increase in energy
Increase with decrease in SSD
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg28
Pronounce with
decrease in SSD and
increase in photon energy and
increase in field size
Increase in surface dose is
due to scattered secondary
electrons from the DAVID
chamber reaching the
water phantom surface
(electron contamination)
6 cm
45 cm
100 cm
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg29
Deconvolution test
by iteration method
IV ResultsDiscussion Deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg3
I Introduction
IMRT (Intensity-modulated radiation therapy)
VMAT (Volumetric Modulated Arc Therapy)
Why In vivo verification
ICRU report 24 (1976) recommended that certain types of tumors
requires improve accuracy from 5 to 35
To detect Equipment-related errors and deviations from the initial plan
Complexity of planning and delivery techniques increases risk for
treatment-related error incidents
In 1992 to 2007 more than 4000 near misses without adverse
outcome to patientrsquos case were reported more than 50 were related
to the planning or treatment delivery stage
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg4
In vivo dosimetry methods
in vivo intracavitary dosimetry with TLD
Diodes
DAVID (Device for Advanced Verification of IMRT deliveries
In-vivo verification during treatment
Online measurement of differences in dose to reference
Error detection of the Multi Leaf Collimator (MLC)
I Introduction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
5
II Theory
Mostly Siemens Elekta and Varian have introduced new LINAC
control systems that will be able to change the MLC leaf positions
IMRT uses many small fields to generated by beam-shaping
devices (MLC) to deliver a single dose of radiation
IMRT Intensity-modulated Radiation Therapie
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg6
II TheoryVMAT Volumetric Modulated Arc Therapy
VMAT is a rotational IMRT that can be delivered using
conventional LINAC with MLC
Elekta and Varian have introduced new LINAC control systems
that will be able to change the MLC leaf positions and dose rate
while the gantry is rotating
Precise Beam infinity and Rapid Arc
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg7
A schematic drawing of the Siemens type A Elekta type B and Varian type C MLC [18]
Stepped leafs for different manufacturers [34]
II Theory
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg8
II Theory Agility MLC design
bull 160 tungsten leafs
bull rounded arc edge
bull 5 mm width
bull High speed(2x normal MLC) of up to
3cmsec
bull large field MLC enable clinicians to
shape radiation
bull extremely low transmission of about
lt05
bull 45 cm isocenter clearance from
accessory holder
MLC Motor
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg9
Inventor
Prof Georges Charpak
France1968
Nobel Prize in Physics (1992)
II Theory Multi wire proportional chamber (MWPC)
The DAVID chamber is a multi-wire
ionization chamber designed by PTW
Freiburg based on Charparks multi wire
proportional chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg10
Compton scattering Electric field causes electrons move to the
anode(wire) and ionizied atomsmolecules to the
cathode(plate)
Each detection wire accumulates charge which
loads a C
After the voltage at the capacitor is read out it is set
to zero and charged again
The voltage achieved is read out by the associated
amplifier at a rate of 1 Hz
Performed by multi-channel electrometer
(MULTIDOS) + additional Software
II Theory DAVID system functioning principle
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
11
Signal interpretation
Ri reading of a single channel (ion charge collected)
C cross section of the lengthy collection volume along the wire
Ii ionization density (x1 start of wire x2 end of wire)
li1-li2 aperture of the associated leave pair
II Theory
II Theory
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
12
Front Plate
Back Plate
Air Volume
II Theory DAVID system signal recording
3 groups of secondary electrons contributing to the signala)ldquoprimary signalrdquo
b)scattered signal
c)leakage radiation
(background signal)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg13
VMAT Planning
Treatment Planning System ONCENTRA Masterplan Version 43
ELEKTA Synergy accelerator with an Agility 80 leaf-pair MLC
bull Desktop Pro TM 7011 is Elektas third generation fully integrated
digital control system MOSAIQ DAVID software version 20
DAVID T34065
III Materials and Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg14
Patient data configuration chart
III Materials amp Methods
Reference
1st session
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg15
DAVID Analysis
bull PTW DAVID 20 software
III Materials amp Methods
Warning level 3
Alarm level 5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg16
III Materials amp Methods
bullVMAT 4 (1 HampN 3 Prostates)
bull180deg to -180deg Clockwise and anti clockwise
Stability of the DAVID system
bullIMRT 1 (Prostate)
bull0deg
bull90deg
bull270deg
(Prostate and Head and Neck) 14 days
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg17
III Materials amp MethodsThe beam property of the DAVID chamber
bullPercentage depth dose (PDD)
bullRoos chamber 34001
bullMP3 water phantom
bullTransmission factor for 6 and 15 MV
bullSemifex T31010 (Diff Field sizes)
Setup conditions
bull With and without DAVID
bull SSD 100 and 80 cm
bull Photon energy 6 and 15
MV
bull Different field sizes
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg18
1 Successive opening of 1 leaf on 1
side
III Materials amp MethodsVMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg19
1 Successive opening of 1 leaf on 1
side
VMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
III Materials amp Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg20
DeconvolutionIII Materials amp Methods
S(x) measured signal as convolution of
P(x) True bdquodoseldquo profile with
LRF fɛ(x)
S(x) = P(x) f(x)
bdquovan Cittertldquo iterative deconvolution
algorithm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg21
opened MLC at every 10th interval from 1st to 80th
pairs
Nine MLC slit through the entire DAVID chamber
IV Results and Discussion Alignment
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg22
IV Results and Discussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT prostate
bull Deviation of plusmn1 (-1)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg23
IV ResultsDiscussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT HampN
bull Deviation of lt05
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg24
IV ResultsDiscussion Transmission factor
The average KDAVID
bull 0939 plusmn0003 for 6 MV
and
bull 0953 plusmn 0004 for 15 MV
Reduction of dose at isocenter
due to 8mm of PMMA
By measuring the attenuation
factor the output value can be
corrected
Attenuation of the beam by the DAVID chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg25
100 cm SSDIncreased about
032 with DAVID
No change of
Dmax
14 cm with
and without DAVID
80 cm SSD
An increased about
426 with DAVID
slight change of
Dmax
13 cm with DAVID
14 cm without DAVID
IV ResultsDiscussion Changes in PDD
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg26
100 cm SSD
An increased about
067 with DAVID
Dmax
26 cm No change
80 cm SSD
An increased about
18 with DAVID
slight change of
Dmax
18 cm with DAVID
24 cm without DAVID
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg27
Surface dose
Increase with increase in field size
Increase with increase in energy
Increase with decrease in SSD
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg28
Pronounce with
decrease in SSD and
increase in photon energy and
increase in field size
Increase in surface dose is
due to scattered secondary
electrons from the DAVID
chamber reaching the
water phantom surface
(electron contamination)
6 cm
45 cm
100 cm
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg29
Deconvolution test
by iteration method
IV ResultsDiscussion Deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg4
In vivo dosimetry methods
in vivo intracavitary dosimetry with TLD
Diodes
DAVID (Device for Advanced Verification of IMRT deliveries
In-vivo verification during treatment
Online measurement of differences in dose to reference
Error detection of the Multi Leaf Collimator (MLC)
I Introduction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
5
II Theory
Mostly Siemens Elekta and Varian have introduced new LINAC
control systems that will be able to change the MLC leaf positions
IMRT uses many small fields to generated by beam-shaping
devices (MLC) to deliver a single dose of radiation
IMRT Intensity-modulated Radiation Therapie
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg6
II TheoryVMAT Volumetric Modulated Arc Therapy
VMAT is a rotational IMRT that can be delivered using
conventional LINAC with MLC
Elekta and Varian have introduced new LINAC control systems
that will be able to change the MLC leaf positions and dose rate
while the gantry is rotating
Precise Beam infinity and Rapid Arc
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg7
A schematic drawing of the Siemens type A Elekta type B and Varian type C MLC [18]
Stepped leafs for different manufacturers [34]
II Theory
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg8
II Theory Agility MLC design
bull 160 tungsten leafs
bull rounded arc edge
bull 5 mm width
bull High speed(2x normal MLC) of up to
3cmsec
bull large field MLC enable clinicians to
shape radiation
bull extremely low transmission of about
lt05
bull 45 cm isocenter clearance from
accessory holder
MLC Motor
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg9
Inventor
Prof Georges Charpak
France1968
Nobel Prize in Physics (1992)
II Theory Multi wire proportional chamber (MWPC)
The DAVID chamber is a multi-wire
ionization chamber designed by PTW
Freiburg based on Charparks multi wire
proportional chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg10
Compton scattering Electric field causes electrons move to the
anode(wire) and ionizied atomsmolecules to the
cathode(plate)
Each detection wire accumulates charge which
loads a C
After the voltage at the capacitor is read out it is set
to zero and charged again
The voltage achieved is read out by the associated
amplifier at a rate of 1 Hz
Performed by multi-channel electrometer
(MULTIDOS) + additional Software
II Theory DAVID system functioning principle
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
11
Signal interpretation
Ri reading of a single channel (ion charge collected)
C cross section of the lengthy collection volume along the wire
Ii ionization density (x1 start of wire x2 end of wire)
li1-li2 aperture of the associated leave pair
II Theory
II Theory
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
12
Front Plate
Back Plate
Air Volume
II Theory DAVID system signal recording
3 groups of secondary electrons contributing to the signala)ldquoprimary signalrdquo
b)scattered signal
c)leakage radiation
(background signal)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg13
VMAT Planning
Treatment Planning System ONCENTRA Masterplan Version 43
ELEKTA Synergy accelerator with an Agility 80 leaf-pair MLC
bull Desktop Pro TM 7011 is Elektas third generation fully integrated
digital control system MOSAIQ DAVID software version 20
DAVID T34065
III Materials and Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg14
Patient data configuration chart
III Materials amp Methods
Reference
1st session
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg15
DAVID Analysis
bull PTW DAVID 20 software
III Materials amp Methods
Warning level 3
Alarm level 5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg16
III Materials amp Methods
bullVMAT 4 (1 HampN 3 Prostates)
bull180deg to -180deg Clockwise and anti clockwise
Stability of the DAVID system
bullIMRT 1 (Prostate)
bull0deg
bull90deg
bull270deg
(Prostate and Head and Neck) 14 days
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg17
III Materials amp MethodsThe beam property of the DAVID chamber
bullPercentage depth dose (PDD)
bullRoos chamber 34001
bullMP3 water phantom
bullTransmission factor for 6 and 15 MV
bullSemifex T31010 (Diff Field sizes)
Setup conditions
bull With and without DAVID
bull SSD 100 and 80 cm
bull Photon energy 6 and 15
MV
bull Different field sizes
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg18
1 Successive opening of 1 leaf on 1
side
III Materials amp MethodsVMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg19
1 Successive opening of 1 leaf on 1
side
VMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
III Materials amp Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg20
DeconvolutionIII Materials amp Methods
S(x) measured signal as convolution of
P(x) True bdquodoseldquo profile with
LRF fɛ(x)
S(x) = P(x) f(x)
bdquovan Cittertldquo iterative deconvolution
algorithm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg21
opened MLC at every 10th interval from 1st to 80th
pairs
Nine MLC slit through the entire DAVID chamber
IV Results and Discussion Alignment
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg22
IV Results and Discussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT prostate
bull Deviation of plusmn1 (-1)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg23
IV ResultsDiscussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT HampN
bull Deviation of lt05
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg24
IV ResultsDiscussion Transmission factor
The average KDAVID
bull 0939 plusmn0003 for 6 MV
and
bull 0953 plusmn 0004 for 15 MV
Reduction of dose at isocenter
due to 8mm of PMMA
By measuring the attenuation
factor the output value can be
corrected
Attenuation of the beam by the DAVID chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg25
100 cm SSDIncreased about
032 with DAVID
No change of
Dmax
14 cm with
and without DAVID
80 cm SSD
An increased about
426 with DAVID
slight change of
Dmax
13 cm with DAVID
14 cm without DAVID
IV ResultsDiscussion Changes in PDD
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg26
100 cm SSD
An increased about
067 with DAVID
Dmax
26 cm No change
80 cm SSD
An increased about
18 with DAVID
slight change of
Dmax
18 cm with DAVID
24 cm without DAVID
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg27
Surface dose
Increase with increase in field size
Increase with increase in energy
Increase with decrease in SSD
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg28
Pronounce with
decrease in SSD and
increase in photon energy and
increase in field size
Increase in surface dose is
due to scattered secondary
electrons from the DAVID
chamber reaching the
water phantom surface
(electron contamination)
6 cm
45 cm
100 cm
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg29
Deconvolution test
by iteration method
IV ResultsDiscussion Deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
5
II Theory
Mostly Siemens Elekta and Varian have introduced new LINAC
control systems that will be able to change the MLC leaf positions
IMRT uses many small fields to generated by beam-shaping
devices (MLC) to deliver a single dose of radiation
IMRT Intensity-modulated Radiation Therapie
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg6
II TheoryVMAT Volumetric Modulated Arc Therapy
VMAT is a rotational IMRT that can be delivered using
conventional LINAC with MLC
Elekta and Varian have introduced new LINAC control systems
that will be able to change the MLC leaf positions and dose rate
while the gantry is rotating
Precise Beam infinity and Rapid Arc
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg7
A schematic drawing of the Siemens type A Elekta type B and Varian type C MLC [18]
Stepped leafs for different manufacturers [34]
II Theory
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg8
II Theory Agility MLC design
bull 160 tungsten leafs
bull rounded arc edge
bull 5 mm width
bull High speed(2x normal MLC) of up to
3cmsec
bull large field MLC enable clinicians to
shape radiation
bull extremely low transmission of about
lt05
bull 45 cm isocenter clearance from
accessory holder
MLC Motor
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg9
Inventor
Prof Georges Charpak
France1968
Nobel Prize in Physics (1992)
II Theory Multi wire proportional chamber (MWPC)
The DAVID chamber is a multi-wire
ionization chamber designed by PTW
Freiburg based on Charparks multi wire
proportional chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg10
Compton scattering Electric field causes electrons move to the
anode(wire) and ionizied atomsmolecules to the
cathode(plate)
Each detection wire accumulates charge which
loads a C
After the voltage at the capacitor is read out it is set
to zero and charged again
The voltage achieved is read out by the associated
amplifier at a rate of 1 Hz
Performed by multi-channel electrometer
(MULTIDOS) + additional Software
II Theory DAVID system functioning principle
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
11
Signal interpretation
Ri reading of a single channel (ion charge collected)
C cross section of the lengthy collection volume along the wire
Ii ionization density (x1 start of wire x2 end of wire)
li1-li2 aperture of the associated leave pair
II Theory
II Theory
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
12
Front Plate
Back Plate
Air Volume
II Theory DAVID system signal recording
3 groups of secondary electrons contributing to the signala)ldquoprimary signalrdquo
b)scattered signal
c)leakage radiation
(background signal)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg13
VMAT Planning
Treatment Planning System ONCENTRA Masterplan Version 43
ELEKTA Synergy accelerator with an Agility 80 leaf-pair MLC
bull Desktop Pro TM 7011 is Elektas third generation fully integrated
digital control system MOSAIQ DAVID software version 20
DAVID T34065
III Materials and Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg14
Patient data configuration chart
III Materials amp Methods
Reference
1st session
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg15
DAVID Analysis
bull PTW DAVID 20 software
III Materials amp Methods
Warning level 3
Alarm level 5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg16
III Materials amp Methods
bullVMAT 4 (1 HampN 3 Prostates)
bull180deg to -180deg Clockwise and anti clockwise
Stability of the DAVID system
bullIMRT 1 (Prostate)
bull0deg
bull90deg
bull270deg
(Prostate and Head and Neck) 14 days
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg17
III Materials amp MethodsThe beam property of the DAVID chamber
bullPercentage depth dose (PDD)
bullRoos chamber 34001
bullMP3 water phantom
bullTransmission factor for 6 and 15 MV
bullSemifex T31010 (Diff Field sizes)
Setup conditions
bull With and without DAVID
bull SSD 100 and 80 cm
bull Photon energy 6 and 15
MV
bull Different field sizes
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg18
1 Successive opening of 1 leaf on 1
side
III Materials amp MethodsVMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg19
1 Successive opening of 1 leaf on 1
side
VMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
III Materials amp Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg20
DeconvolutionIII Materials amp Methods
S(x) measured signal as convolution of
P(x) True bdquodoseldquo profile with
LRF fɛ(x)
S(x) = P(x) f(x)
bdquovan Cittertldquo iterative deconvolution
algorithm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg21
opened MLC at every 10th interval from 1st to 80th
pairs
Nine MLC slit through the entire DAVID chamber
IV Results and Discussion Alignment
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg22
IV Results and Discussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT prostate
bull Deviation of plusmn1 (-1)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg23
IV ResultsDiscussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT HampN
bull Deviation of lt05
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg24
IV ResultsDiscussion Transmission factor
The average KDAVID
bull 0939 plusmn0003 for 6 MV
and
bull 0953 plusmn 0004 for 15 MV
Reduction of dose at isocenter
due to 8mm of PMMA
By measuring the attenuation
factor the output value can be
corrected
Attenuation of the beam by the DAVID chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg25
100 cm SSDIncreased about
032 with DAVID
No change of
Dmax
14 cm with
and without DAVID
80 cm SSD
An increased about
426 with DAVID
slight change of
Dmax
13 cm with DAVID
14 cm without DAVID
IV ResultsDiscussion Changes in PDD
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg26
100 cm SSD
An increased about
067 with DAVID
Dmax
26 cm No change
80 cm SSD
An increased about
18 with DAVID
slight change of
Dmax
18 cm with DAVID
24 cm without DAVID
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg27
Surface dose
Increase with increase in field size
Increase with increase in energy
Increase with decrease in SSD
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg28
Pronounce with
decrease in SSD and
increase in photon energy and
increase in field size
Increase in surface dose is
due to scattered secondary
electrons from the DAVID
chamber reaching the
water phantom surface
(electron contamination)
6 cm
45 cm
100 cm
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg29
Deconvolution test
by iteration method
IV ResultsDiscussion Deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg6
II TheoryVMAT Volumetric Modulated Arc Therapy
VMAT is a rotational IMRT that can be delivered using
conventional LINAC with MLC
Elekta and Varian have introduced new LINAC control systems
that will be able to change the MLC leaf positions and dose rate
while the gantry is rotating
Precise Beam infinity and Rapid Arc
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg7
A schematic drawing of the Siemens type A Elekta type B and Varian type C MLC [18]
Stepped leafs for different manufacturers [34]
II Theory
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg8
II Theory Agility MLC design
bull 160 tungsten leafs
bull rounded arc edge
bull 5 mm width
bull High speed(2x normal MLC) of up to
3cmsec
bull large field MLC enable clinicians to
shape radiation
bull extremely low transmission of about
lt05
bull 45 cm isocenter clearance from
accessory holder
MLC Motor
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg9
Inventor
Prof Georges Charpak
France1968
Nobel Prize in Physics (1992)
II Theory Multi wire proportional chamber (MWPC)
The DAVID chamber is a multi-wire
ionization chamber designed by PTW
Freiburg based on Charparks multi wire
proportional chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg10
Compton scattering Electric field causes electrons move to the
anode(wire) and ionizied atomsmolecules to the
cathode(plate)
Each detection wire accumulates charge which
loads a C
After the voltage at the capacitor is read out it is set
to zero and charged again
The voltage achieved is read out by the associated
amplifier at a rate of 1 Hz
Performed by multi-channel electrometer
(MULTIDOS) + additional Software
II Theory DAVID system functioning principle
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
11
Signal interpretation
Ri reading of a single channel (ion charge collected)
C cross section of the lengthy collection volume along the wire
Ii ionization density (x1 start of wire x2 end of wire)
li1-li2 aperture of the associated leave pair
II Theory
II Theory
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
12
Front Plate
Back Plate
Air Volume
II Theory DAVID system signal recording
3 groups of secondary electrons contributing to the signala)ldquoprimary signalrdquo
b)scattered signal
c)leakage radiation
(background signal)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg13
VMAT Planning
Treatment Planning System ONCENTRA Masterplan Version 43
ELEKTA Synergy accelerator with an Agility 80 leaf-pair MLC
bull Desktop Pro TM 7011 is Elektas third generation fully integrated
digital control system MOSAIQ DAVID software version 20
DAVID T34065
III Materials and Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg14
Patient data configuration chart
III Materials amp Methods
Reference
1st session
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg15
DAVID Analysis
bull PTW DAVID 20 software
III Materials amp Methods
Warning level 3
Alarm level 5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg16
III Materials amp Methods
bullVMAT 4 (1 HampN 3 Prostates)
bull180deg to -180deg Clockwise and anti clockwise
Stability of the DAVID system
bullIMRT 1 (Prostate)
bull0deg
bull90deg
bull270deg
(Prostate and Head and Neck) 14 days
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg17
III Materials amp MethodsThe beam property of the DAVID chamber
bullPercentage depth dose (PDD)
bullRoos chamber 34001
bullMP3 water phantom
bullTransmission factor for 6 and 15 MV
bullSemifex T31010 (Diff Field sizes)
Setup conditions
bull With and without DAVID
bull SSD 100 and 80 cm
bull Photon energy 6 and 15
MV
bull Different field sizes
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg18
1 Successive opening of 1 leaf on 1
side
III Materials amp MethodsVMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg19
1 Successive opening of 1 leaf on 1
side
VMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
III Materials amp Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg20
DeconvolutionIII Materials amp Methods
S(x) measured signal as convolution of
P(x) True bdquodoseldquo profile with
LRF fɛ(x)
S(x) = P(x) f(x)
bdquovan Cittertldquo iterative deconvolution
algorithm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg21
opened MLC at every 10th interval from 1st to 80th
pairs
Nine MLC slit through the entire DAVID chamber
IV Results and Discussion Alignment
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg22
IV Results and Discussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT prostate
bull Deviation of plusmn1 (-1)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg23
IV ResultsDiscussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT HampN
bull Deviation of lt05
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg24
IV ResultsDiscussion Transmission factor
The average KDAVID
bull 0939 plusmn0003 for 6 MV
and
bull 0953 plusmn 0004 for 15 MV
Reduction of dose at isocenter
due to 8mm of PMMA
By measuring the attenuation
factor the output value can be
corrected
Attenuation of the beam by the DAVID chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg25
100 cm SSDIncreased about
032 with DAVID
No change of
Dmax
14 cm with
and without DAVID
80 cm SSD
An increased about
426 with DAVID
slight change of
Dmax
13 cm with DAVID
14 cm without DAVID
IV ResultsDiscussion Changes in PDD
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg26
100 cm SSD
An increased about
067 with DAVID
Dmax
26 cm No change
80 cm SSD
An increased about
18 with DAVID
slight change of
Dmax
18 cm with DAVID
24 cm without DAVID
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg27
Surface dose
Increase with increase in field size
Increase with increase in energy
Increase with decrease in SSD
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg28
Pronounce with
decrease in SSD and
increase in photon energy and
increase in field size
Increase in surface dose is
due to scattered secondary
electrons from the DAVID
chamber reaching the
water phantom surface
(electron contamination)
6 cm
45 cm
100 cm
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg29
Deconvolution test
by iteration method
IV ResultsDiscussion Deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg7
A schematic drawing of the Siemens type A Elekta type B and Varian type C MLC [18]
Stepped leafs for different manufacturers [34]
II Theory
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg8
II Theory Agility MLC design
bull 160 tungsten leafs
bull rounded arc edge
bull 5 mm width
bull High speed(2x normal MLC) of up to
3cmsec
bull large field MLC enable clinicians to
shape radiation
bull extremely low transmission of about
lt05
bull 45 cm isocenter clearance from
accessory holder
MLC Motor
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg9
Inventor
Prof Georges Charpak
France1968
Nobel Prize in Physics (1992)
II Theory Multi wire proportional chamber (MWPC)
The DAVID chamber is a multi-wire
ionization chamber designed by PTW
Freiburg based on Charparks multi wire
proportional chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg10
Compton scattering Electric field causes electrons move to the
anode(wire) and ionizied atomsmolecules to the
cathode(plate)
Each detection wire accumulates charge which
loads a C
After the voltage at the capacitor is read out it is set
to zero and charged again
The voltage achieved is read out by the associated
amplifier at a rate of 1 Hz
Performed by multi-channel electrometer
(MULTIDOS) + additional Software
II Theory DAVID system functioning principle
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
11
Signal interpretation
Ri reading of a single channel (ion charge collected)
C cross section of the lengthy collection volume along the wire
Ii ionization density (x1 start of wire x2 end of wire)
li1-li2 aperture of the associated leave pair
II Theory
II Theory
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
12
Front Plate
Back Plate
Air Volume
II Theory DAVID system signal recording
3 groups of secondary electrons contributing to the signala)ldquoprimary signalrdquo
b)scattered signal
c)leakage radiation
(background signal)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg13
VMAT Planning
Treatment Planning System ONCENTRA Masterplan Version 43
ELEKTA Synergy accelerator with an Agility 80 leaf-pair MLC
bull Desktop Pro TM 7011 is Elektas third generation fully integrated
digital control system MOSAIQ DAVID software version 20
DAVID T34065
III Materials and Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg14
Patient data configuration chart
III Materials amp Methods
Reference
1st session
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg15
DAVID Analysis
bull PTW DAVID 20 software
III Materials amp Methods
Warning level 3
Alarm level 5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg16
III Materials amp Methods
bullVMAT 4 (1 HampN 3 Prostates)
bull180deg to -180deg Clockwise and anti clockwise
Stability of the DAVID system
bullIMRT 1 (Prostate)
bull0deg
bull90deg
bull270deg
(Prostate and Head and Neck) 14 days
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg17
III Materials amp MethodsThe beam property of the DAVID chamber
bullPercentage depth dose (PDD)
bullRoos chamber 34001
bullMP3 water phantom
bullTransmission factor for 6 and 15 MV
bullSemifex T31010 (Diff Field sizes)
Setup conditions
bull With and without DAVID
bull SSD 100 and 80 cm
bull Photon energy 6 and 15
MV
bull Different field sizes
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg18
1 Successive opening of 1 leaf on 1
side
III Materials amp MethodsVMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg19
1 Successive opening of 1 leaf on 1
side
VMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
III Materials amp Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg20
DeconvolutionIII Materials amp Methods
S(x) measured signal as convolution of
P(x) True bdquodoseldquo profile with
LRF fɛ(x)
S(x) = P(x) f(x)
bdquovan Cittertldquo iterative deconvolution
algorithm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg21
opened MLC at every 10th interval from 1st to 80th
pairs
Nine MLC slit through the entire DAVID chamber
IV Results and Discussion Alignment
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg22
IV Results and Discussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT prostate
bull Deviation of plusmn1 (-1)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg23
IV ResultsDiscussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT HampN
bull Deviation of lt05
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg24
IV ResultsDiscussion Transmission factor
The average KDAVID
bull 0939 plusmn0003 for 6 MV
and
bull 0953 plusmn 0004 for 15 MV
Reduction of dose at isocenter
due to 8mm of PMMA
By measuring the attenuation
factor the output value can be
corrected
Attenuation of the beam by the DAVID chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg25
100 cm SSDIncreased about
032 with DAVID
No change of
Dmax
14 cm with
and without DAVID
80 cm SSD
An increased about
426 with DAVID
slight change of
Dmax
13 cm with DAVID
14 cm without DAVID
IV ResultsDiscussion Changes in PDD
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg26
100 cm SSD
An increased about
067 with DAVID
Dmax
26 cm No change
80 cm SSD
An increased about
18 with DAVID
slight change of
Dmax
18 cm with DAVID
24 cm without DAVID
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg27
Surface dose
Increase with increase in field size
Increase with increase in energy
Increase with decrease in SSD
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg28
Pronounce with
decrease in SSD and
increase in photon energy and
increase in field size
Increase in surface dose is
due to scattered secondary
electrons from the DAVID
chamber reaching the
water phantom surface
(electron contamination)
6 cm
45 cm
100 cm
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg29
Deconvolution test
by iteration method
IV ResultsDiscussion Deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg8
II Theory Agility MLC design
bull 160 tungsten leafs
bull rounded arc edge
bull 5 mm width
bull High speed(2x normal MLC) of up to
3cmsec
bull large field MLC enable clinicians to
shape radiation
bull extremely low transmission of about
lt05
bull 45 cm isocenter clearance from
accessory holder
MLC Motor
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg9
Inventor
Prof Georges Charpak
France1968
Nobel Prize in Physics (1992)
II Theory Multi wire proportional chamber (MWPC)
The DAVID chamber is a multi-wire
ionization chamber designed by PTW
Freiburg based on Charparks multi wire
proportional chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg10
Compton scattering Electric field causes electrons move to the
anode(wire) and ionizied atomsmolecules to the
cathode(plate)
Each detection wire accumulates charge which
loads a C
After the voltage at the capacitor is read out it is set
to zero and charged again
The voltage achieved is read out by the associated
amplifier at a rate of 1 Hz
Performed by multi-channel electrometer
(MULTIDOS) + additional Software
II Theory DAVID system functioning principle
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
11
Signal interpretation
Ri reading of a single channel (ion charge collected)
C cross section of the lengthy collection volume along the wire
Ii ionization density (x1 start of wire x2 end of wire)
li1-li2 aperture of the associated leave pair
II Theory
II Theory
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
12
Front Plate
Back Plate
Air Volume
II Theory DAVID system signal recording
3 groups of secondary electrons contributing to the signala)ldquoprimary signalrdquo
b)scattered signal
c)leakage radiation
(background signal)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg13
VMAT Planning
Treatment Planning System ONCENTRA Masterplan Version 43
ELEKTA Synergy accelerator with an Agility 80 leaf-pair MLC
bull Desktop Pro TM 7011 is Elektas third generation fully integrated
digital control system MOSAIQ DAVID software version 20
DAVID T34065
III Materials and Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg14
Patient data configuration chart
III Materials amp Methods
Reference
1st session
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg15
DAVID Analysis
bull PTW DAVID 20 software
III Materials amp Methods
Warning level 3
Alarm level 5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg16
III Materials amp Methods
bullVMAT 4 (1 HampN 3 Prostates)
bull180deg to -180deg Clockwise and anti clockwise
Stability of the DAVID system
bullIMRT 1 (Prostate)
bull0deg
bull90deg
bull270deg
(Prostate and Head and Neck) 14 days
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg17
III Materials amp MethodsThe beam property of the DAVID chamber
bullPercentage depth dose (PDD)
bullRoos chamber 34001
bullMP3 water phantom
bullTransmission factor for 6 and 15 MV
bullSemifex T31010 (Diff Field sizes)
Setup conditions
bull With and without DAVID
bull SSD 100 and 80 cm
bull Photon energy 6 and 15
MV
bull Different field sizes
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg18
1 Successive opening of 1 leaf on 1
side
III Materials amp MethodsVMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg19
1 Successive opening of 1 leaf on 1
side
VMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
III Materials amp Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg20
DeconvolutionIII Materials amp Methods
S(x) measured signal as convolution of
P(x) True bdquodoseldquo profile with
LRF fɛ(x)
S(x) = P(x) f(x)
bdquovan Cittertldquo iterative deconvolution
algorithm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg21
opened MLC at every 10th interval from 1st to 80th
pairs
Nine MLC slit through the entire DAVID chamber
IV Results and Discussion Alignment
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg22
IV Results and Discussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT prostate
bull Deviation of plusmn1 (-1)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg23
IV ResultsDiscussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT HampN
bull Deviation of lt05
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg24
IV ResultsDiscussion Transmission factor
The average KDAVID
bull 0939 plusmn0003 for 6 MV
and
bull 0953 plusmn 0004 for 15 MV
Reduction of dose at isocenter
due to 8mm of PMMA
By measuring the attenuation
factor the output value can be
corrected
Attenuation of the beam by the DAVID chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg25
100 cm SSDIncreased about
032 with DAVID
No change of
Dmax
14 cm with
and without DAVID
80 cm SSD
An increased about
426 with DAVID
slight change of
Dmax
13 cm with DAVID
14 cm without DAVID
IV ResultsDiscussion Changes in PDD
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg26
100 cm SSD
An increased about
067 with DAVID
Dmax
26 cm No change
80 cm SSD
An increased about
18 with DAVID
slight change of
Dmax
18 cm with DAVID
24 cm without DAVID
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg27
Surface dose
Increase with increase in field size
Increase with increase in energy
Increase with decrease in SSD
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg28
Pronounce with
decrease in SSD and
increase in photon energy and
increase in field size
Increase in surface dose is
due to scattered secondary
electrons from the DAVID
chamber reaching the
water phantom surface
(electron contamination)
6 cm
45 cm
100 cm
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg29
Deconvolution test
by iteration method
IV ResultsDiscussion Deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg9
Inventor
Prof Georges Charpak
France1968
Nobel Prize in Physics (1992)
II Theory Multi wire proportional chamber (MWPC)
The DAVID chamber is a multi-wire
ionization chamber designed by PTW
Freiburg based on Charparks multi wire
proportional chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg10
Compton scattering Electric field causes electrons move to the
anode(wire) and ionizied atomsmolecules to the
cathode(plate)
Each detection wire accumulates charge which
loads a C
After the voltage at the capacitor is read out it is set
to zero and charged again
The voltage achieved is read out by the associated
amplifier at a rate of 1 Hz
Performed by multi-channel electrometer
(MULTIDOS) + additional Software
II Theory DAVID system functioning principle
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
11
Signal interpretation
Ri reading of a single channel (ion charge collected)
C cross section of the lengthy collection volume along the wire
Ii ionization density (x1 start of wire x2 end of wire)
li1-li2 aperture of the associated leave pair
II Theory
II Theory
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
12
Front Plate
Back Plate
Air Volume
II Theory DAVID system signal recording
3 groups of secondary electrons contributing to the signala)ldquoprimary signalrdquo
b)scattered signal
c)leakage radiation
(background signal)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg13
VMAT Planning
Treatment Planning System ONCENTRA Masterplan Version 43
ELEKTA Synergy accelerator with an Agility 80 leaf-pair MLC
bull Desktop Pro TM 7011 is Elektas third generation fully integrated
digital control system MOSAIQ DAVID software version 20
DAVID T34065
III Materials and Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg14
Patient data configuration chart
III Materials amp Methods
Reference
1st session
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg15
DAVID Analysis
bull PTW DAVID 20 software
III Materials amp Methods
Warning level 3
Alarm level 5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg16
III Materials amp Methods
bullVMAT 4 (1 HampN 3 Prostates)
bull180deg to -180deg Clockwise and anti clockwise
Stability of the DAVID system
bullIMRT 1 (Prostate)
bull0deg
bull90deg
bull270deg
(Prostate and Head and Neck) 14 days
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg17
III Materials amp MethodsThe beam property of the DAVID chamber
bullPercentage depth dose (PDD)
bullRoos chamber 34001
bullMP3 water phantom
bullTransmission factor for 6 and 15 MV
bullSemifex T31010 (Diff Field sizes)
Setup conditions
bull With and without DAVID
bull SSD 100 and 80 cm
bull Photon energy 6 and 15
MV
bull Different field sizes
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg18
1 Successive opening of 1 leaf on 1
side
III Materials amp MethodsVMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg19
1 Successive opening of 1 leaf on 1
side
VMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
III Materials amp Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg20
DeconvolutionIII Materials amp Methods
S(x) measured signal as convolution of
P(x) True bdquodoseldquo profile with
LRF fɛ(x)
S(x) = P(x) f(x)
bdquovan Cittertldquo iterative deconvolution
algorithm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg21
opened MLC at every 10th interval from 1st to 80th
pairs
Nine MLC slit through the entire DAVID chamber
IV Results and Discussion Alignment
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg22
IV Results and Discussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT prostate
bull Deviation of plusmn1 (-1)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg23
IV ResultsDiscussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT HampN
bull Deviation of lt05
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg24
IV ResultsDiscussion Transmission factor
The average KDAVID
bull 0939 plusmn0003 for 6 MV
and
bull 0953 plusmn 0004 for 15 MV
Reduction of dose at isocenter
due to 8mm of PMMA
By measuring the attenuation
factor the output value can be
corrected
Attenuation of the beam by the DAVID chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg25
100 cm SSDIncreased about
032 with DAVID
No change of
Dmax
14 cm with
and without DAVID
80 cm SSD
An increased about
426 with DAVID
slight change of
Dmax
13 cm with DAVID
14 cm without DAVID
IV ResultsDiscussion Changes in PDD
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg26
100 cm SSD
An increased about
067 with DAVID
Dmax
26 cm No change
80 cm SSD
An increased about
18 with DAVID
slight change of
Dmax
18 cm with DAVID
24 cm without DAVID
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg27
Surface dose
Increase with increase in field size
Increase with increase in energy
Increase with decrease in SSD
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg28
Pronounce with
decrease in SSD and
increase in photon energy and
increase in field size
Increase in surface dose is
due to scattered secondary
electrons from the DAVID
chamber reaching the
water phantom surface
(electron contamination)
6 cm
45 cm
100 cm
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg29
Deconvolution test
by iteration method
IV ResultsDiscussion Deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg10
Compton scattering Electric field causes electrons move to the
anode(wire) and ionizied atomsmolecules to the
cathode(plate)
Each detection wire accumulates charge which
loads a C
After the voltage at the capacitor is read out it is set
to zero and charged again
The voltage achieved is read out by the associated
amplifier at a rate of 1 Hz
Performed by multi-channel electrometer
(MULTIDOS) + additional Software
II Theory DAVID system functioning principle
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
11
Signal interpretation
Ri reading of a single channel (ion charge collected)
C cross section of the lengthy collection volume along the wire
Ii ionization density (x1 start of wire x2 end of wire)
li1-li2 aperture of the associated leave pair
II Theory
II Theory
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
12
Front Plate
Back Plate
Air Volume
II Theory DAVID system signal recording
3 groups of secondary electrons contributing to the signala)ldquoprimary signalrdquo
b)scattered signal
c)leakage radiation
(background signal)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg13
VMAT Planning
Treatment Planning System ONCENTRA Masterplan Version 43
ELEKTA Synergy accelerator with an Agility 80 leaf-pair MLC
bull Desktop Pro TM 7011 is Elektas third generation fully integrated
digital control system MOSAIQ DAVID software version 20
DAVID T34065
III Materials and Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg14
Patient data configuration chart
III Materials amp Methods
Reference
1st session
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg15
DAVID Analysis
bull PTW DAVID 20 software
III Materials amp Methods
Warning level 3
Alarm level 5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg16
III Materials amp Methods
bullVMAT 4 (1 HampN 3 Prostates)
bull180deg to -180deg Clockwise and anti clockwise
Stability of the DAVID system
bullIMRT 1 (Prostate)
bull0deg
bull90deg
bull270deg
(Prostate and Head and Neck) 14 days
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg17
III Materials amp MethodsThe beam property of the DAVID chamber
bullPercentage depth dose (PDD)
bullRoos chamber 34001
bullMP3 water phantom
bullTransmission factor for 6 and 15 MV
bullSemifex T31010 (Diff Field sizes)
Setup conditions
bull With and without DAVID
bull SSD 100 and 80 cm
bull Photon energy 6 and 15
MV
bull Different field sizes
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg18
1 Successive opening of 1 leaf on 1
side
III Materials amp MethodsVMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg19
1 Successive opening of 1 leaf on 1
side
VMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
III Materials amp Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg20
DeconvolutionIII Materials amp Methods
S(x) measured signal as convolution of
P(x) True bdquodoseldquo profile with
LRF fɛ(x)
S(x) = P(x) f(x)
bdquovan Cittertldquo iterative deconvolution
algorithm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg21
opened MLC at every 10th interval from 1st to 80th
pairs
Nine MLC slit through the entire DAVID chamber
IV Results and Discussion Alignment
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg22
IV Results and Discussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT prostate
bull Deviation of plusmn1 (-1)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg23
IV ResultsDiscussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT HampN
bull Deviation of lt05
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg24
IV ResultsDiscussion Transmission factor
The average KDAVID
bull 0939 plusmn0003 for 6 MV
and
bull 0953 plusmn 0004 for 15 MV
Reduction of dose at isocenter
due to 8mm of PMMA
By measuring the attenuation
factor the output value can be
corrected
Attenuation of the beam by the DAVID chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg25
100 cm SSDIncreased about
032 with DAVID
No change of
Dmax
14 cm with
and without DAVID
80 cm SSD
An increased about
426 with DAVID
slight change of
Dmax
13 cm with DAVID
14 cm without DAVID
IV ResultsDiscussion Changes in PDD
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg26
100 cm SSD
An increased about
067 with DAVID
Dmax
26 cm No change
80 cm SSD
An increased about
18 with DAVID
slight change of
Dmax
18 cm with DAVID
24 cm without DAVID
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg27
Surface dose
Increase with increase in field size
Increase with increase in energy
Increase with decrease in SSD
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg28
Pronounce with
decrease in SSD and
increase in photon energy and
increase in field size
Increase in surface dose is
due to scattered secondary
electrons from the DAVID
chamber reaching the
water phantom surface
(electron contamination)
6 cm
45 cm
100 cm
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg29
Deconvolution test
by iteration method
IV ResultsDiscussion Deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
11
Signal interpretation
Ri reading of a single channel (ion charge collected)
C cross section of the lengthy collection volume along the wire
Ii ionization density (x1 start of wire x2 end of wire)
li1-li2 aperture of the associated leave pair
II Theory
II Theory
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
12
Front Plate
Back Plate
Air Volume
II Theory DAVID system signal recording
3 groups of secondary electrons contributing to the signala)ldquoprimary signalrdquo
b)scattered signal
c)leakage radiation
(background signal)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg13
VMAT Planning
Treatment Planning System ONCENTRA Masterplan Version 43
ELEKTA Synergy accelerator with an Agility 80 leaf-pair MLC
bull Desktop Pro TM 7011 is Elektas third generation fully integrated
digital control system MOSAIQ DAVID software version 20
DAVID T34065
III Materials and Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg14
Patient data configuration chart
III Materials amp Methods
Reference
1st session
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg15
DAVID Analysis
bull PTW DAVID 20 software
III Materials amp Methods
Warning level 3
Alarm level 5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg16
III Materials amp Methods
bullVMAT 4 (1 HampN 3 Prostates)
bull180deg to -180deg Clockwise and anti clockwise
Stability of the DAVID system
bullIMRT 1 (Prostate)
bull0deg
bull90deg
bull270deg
(Prostate and Head and Neck) 14 days
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg17
III Materials amp MethodsThe beam property of the DAVID chamber
bullPercentage depth dose (PDD)
bullRoos chamber 34001
bullMP3 water phantom
bullTransmission factor for 6 and 15 MV
bullSemifex T31010 (Diff Field sizes)
Setup conditions
bull With and without DAVID
bull SSD 100 and 80 cm
bull Photon energy 6 and 15
MV
bull Different field sizes
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg18
1 Successive opening of 1 leaf on 1
side
III Materials amp MethodsVMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg19
1 Successive opening of 1 leaf on 1
side
VMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
III Materials amp Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg20
DeconvolutionIII Materials amp Methods
S(x) measured signal as convolution of
P(x) True bdquodoseldquo profile with
LRF fɛ(x)
S(x) = P(x) f(x)
bdquovan Cittertldquo iterative deconvolution
algorithm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg21
opened MLC at every 10th interval from 1st to 80th
pairs
Nine MLC slit through the entire DAVID chamber
IV Results and Discussion Alignment
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg22
IV Results and Discussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT prostate
bull Deviation of plusmn1 (-1)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg23
IV ResultsDiscussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT HampN
bull Deviation of lt05
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg24
IV ResultsDiscussion Transmission factor
The average KDAVID
bull 0939 plusmn0003 for 6 MV
and
bull 0953 plusmn 0004 for 15 MV
Reduction of dose at isocenter
due to 8mm of PMMA
By measuring the attenuation
factor the output value can be
corrected
Attenuation of the beam by the DAVID chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg25
100 cm SSDIncreased about
032 with DAVID
No change of
Dmax
14 cm with
and without DAVID
80 cm SSD
An increased about
426 with DAVID
slight change of
Dmax
13 cm with DAVID
14 cm without DAVID
IV ResultsDiscussion Changes in PDD
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg26
100 cm SSD
An increased about
067 with DAVID
Dmax
26 cm No change
80 cm SSD
An increased about
18 with DAVID
slight change of
Dmax
18 cm with DAVID
24 cm without DAVID
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg27
Surface dose
Increase with increase in field size
Increase with increase in energy
Increase with decrease in SSD
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg28
Pronounce with
decrease in SSD and
increase in photon energy and
increase in field size
Increase in surface dose is
due to scattered secondary
electrons from the DAVID
chamber reaching the
water phantom surface
(electron contamination)
6 cm
45 cm
100 cm
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg29
Deconvolution test
by iteration method
IV ResultsDiscussion Deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
12
Front Plate
Back Plate
Air Volume
II Theory DAVID system signal recording
3 groups of secondary electrons contributing to the signala)ldquoprimary signalrdquo
b)scattered signal
c)leakage radiation
(background signal)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg13
VMAT Planning
Treatment Planning System ONCENTRA Masterplan Version 43
ELEKTA Synergy accelerator with an Agility 80 leaf-pair MLC
bull Desktop Pro TM 7011 is Elektas third generation fully integrated
digital control system MOSAIQ DAVID software version 20
DAVID T34065
III Materials and Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg14
Patient data configuration chart
III Materials amp Methods
Reference
1st session
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg15
DAVID Analysis
bull PTW DAVID 20 software
III Materials amp Methods
Warning level 3
Alarm level 5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg16
III Materials amp Methods
bullVMAT 4 (1 HampN 3 Prostates)
bull180deg to -180deg Clockwise and anti clockwise
Stability of the DAVID system
bullIMRT 1 (Prostate)
bull0deg
bull90deg
bull270deg
(Prostate and Head and Neck) 14 days
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg17
III Materials amp MethodsThe beam property of the DAVID chamber
bullPercentage depth dose (PDD)
bullRoos chamber 34001
bullMP3 water phantom
bullTransmission factor for 6 and 15 MV
bullSemifex T31010 (Diff Field sizes)
Setup conditions
bull With and without DAVID
bull SSD 100 and 80 cm
bull Photon energy 6 and 15
MV
bull Different field sizes
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg18
1 Successive opening of 1 leaf on 1
side
III Materials amp MethodsVMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg19
1 Successive opening of 1 leaf on 1
side
VMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
III Materials amp Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg20
DeconvolutionIII Materials amp Methods
S(x) measured signal as convolution of
P(x) True bdquodoseldquo profile with
LRF fɛ(x)
S(x) = P(x) f(x)
bdquovan Cittertldquo iterative deconvolution
algorithm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg21
opened MLC at every 10th interval from 1st to 80th
pairs
Nine MLC slit through the entire DAVID chamber
IV Results and Discussion Alignment
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg22
IV Results and Discussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT prostate
bull Deviation of plusmn1 (-1)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg23
IV ResultsDiscussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT HampN
bull Deviation of lt05
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg24
IV ResultsDiscussion Transmission factor
The average KDAVID
bull 0939 plusmn0003 for 6 MV
and
bull 0953 plusmn 0004 for 15 MV
Reduction of dose at isocenter
due to 8mm of PMMA
By measuring the attenuation
factor the output value can be
corrected
Attenuation of the beam by the DAVID chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg25
100 cm SSDIncreased about
032 with DAVID
No change of
Dmax
14 cm with
and without DAVID
80 cm SSD
An increased about
426 with DAVID
slight change of
Dmax
13 cm with DAVID
14 cm without DAVID
IV ResultsDiscussion Changes in PDD
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg26
100 cm SSD
An increased about
067 with DAVID
Dmax
26 cm No change
80 cm SSD
An increased about
18 with DAVID
slight change of
Dmax
18 cm with DAVID
24 cm without DAVID
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg27
Surface dose
Increase with increase in field size
Increase with increase in energy
Increase with decrease in SSD
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg28
Pronounce with
decrease in SSD and
increase in photon energy and
increase in field size
Increase in surface dose is
due to scattered secondary
electrons from the DAVID
chamber reaching the
water phantom surface
(electron contamination)
6 cm
45 cm
100 cm
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg29
Deconvolution test
by iteration method
IV ResultsDiscussion Deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg13
VMAT Planning
Treatment Planning System ONCENTRA Masterplan Version 43
ELEKTA Synergy accelerator with an Agility 80 leaf-pair MLC
bull Desktop Pro TM 7011 is Elektas third generation fully integrated
digital control system MOSAIQ DAVID software version 20
DAVID T34065
III Materials and Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg14
Patient data configuration chart
III Materials amp Methods
Reference
1st session
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg15
DAVID Analysis
bull PTW DAVID 20 software
III Materials amp Methods
Warning level 3
Alarm level 5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg16
III Materials amp Methods
bullVMAT 4 (1 HampN 3 Prostates)
bull180deg to -180deg Clockwise and anti clockwise
Stability of the DAVID system
bullIMRT 1 (Prostate)
bull0deg
bull90deg
bull270deg
(Prostate and Head and Neck) 14 days
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg17
III Materials amp MethodsThe beam property of the DAVID chamber
bullPercentage depth dose (PDD)
bullRoos chamber 34001
bullMP3 water phantom
bullTransmission factor for 6 and 15 MV
bullSemifex T31010 (Diff Field sizes)
Setup conditions
bull With and without DAVID
bull SSD 100 and 80 cm
bull Photon energy 6 and 15
MV
bull Different field sizes
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg18
1 Successive opening of 1 leaf on 1
side
III Materials amp MethodsVMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg19
1 Successive opening of 1 leaf on 1
side
VMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
III Materials amp Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg20
DeconvolutionIII Materials amp Methods
S(x) measured signal as convolution of
P(x) True bdquodoseldquo profile with
LRF fɛ(x)
S(x) = P(x) f(x)
bdquovan Cittertldquo iterative deconvolution
algorithm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg21
opened MLC at every 10th interval from 1st to 80th
pairs
Nine MLC slit through the entire DAVID chamber
IV Results and Discussion Alignment
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg22
IV Results and Discussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT prostate
bull Deviation of plusmn1 (-1)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg23
IV ResultsDiscussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT HampN
bull Deviation of lt05
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg24
IV ResultsDiscussion Transmission factor
The average KDAVID
bull 0939 plusmn0003 for 6 MV
and
bull 0953 plusmn 0004 for 15 MV
Reduction of dose at isocenter
due to 8mm of PMMA
By measuring the attenuation
factor the output value can be
corrected
Attenuation of the beam by the DAVID chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg25
100 cm SSDIncreased about
032 with DAVID
No change of
Dmax
14 cm with
and without DAVID
80 cm SSD
An increased about
426 with DAVID
slight change of
Dmax
13 cm with DAVID
14 cm without DAVID
IV ResultsDiscussion Changes in PDD
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg26
100 cm SSD
An increased about
067 with DAVID
Dmax
26 cm No change
80 cm SSD
An increased about
18 with DAVID
slight change of
Dmax
18 cm with DAVID
24 cm without DAVID
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg27
Surface dose
Increase with increase in field size
Increase with increase in energy
Increase with decrease in SSD
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg28
Pronounce with
decrease in SSD and
increase in photon energy and
increase in field size
Increase in surface dose is
due to scattered secondary
electrons from the DAVID
chamber reaching the
water phantom surface
(electron contamination)
6 cm
45 cm
100 cm
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg29
Deconvolution test
by iteration method
IV ResultsDiscussion Deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg14
Patient data configuration chart
III Materials amp Methods
Reference
1st session
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg15
DAVID Analysis
bull PTW DAVID 20 software
III Materials amp Methods
Warning level 3
Alarm level 5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg16
III Materials amp Methods
bullVMAT 4 (1 HampN 3 Prostates)
bull180deg to -180deg Clockwise and anti clockwise
Stability of the DAVID system
bullIMRT 1 (Prostate)
bull0deg
bull90deg
bull270deg
(Prostate and Head and Neck) 14 days
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg17
III Materials amp MethodsThe beam property of the DAVID chamber
bullPercentage depth dose (PDD)
bullRoos chamber 34001
bullMP3 water phantom
bullTransmission factor for 6 and 15 MV
bullSemifex T31010 (Diff Field sizes)
Setup conditions
bull With and without DAVID
bull SSD 100 and 80 cm
bull Photon energy 6 and 15
MV
bull Different field sizes
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg18
1 Successive opening of 1 leaf on 1
side
III Materials amp MethodsVMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg19
1 Successive opening of 1 leaf on 1
side
VMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
III Materials amp Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg20
DeconvolutionIII Materials amp Methods
S(x) measured signal as convolution of
P(x) True bdquodoseldquo profile with
LRF fɛ(x)
S(x) = P(x) f(x)
bdquovan Cittertldquo iterative deconvolution
algorithm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg21
opened MLC at every 10th interval from 1st to 80th
pairs
Nine MLC slit through the entire DAVID chamber
IV Results and Discussion Alignment
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg22
IV Results and Discussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT prostate
bull Deviation of plusmn1 (-1)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg23
IV ResultsDiscussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT HampN
bull Deviation of lt05
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg24
IV ResultsDiscussion Transmission factor
The average KDAVID
bull 0939 plusmn0003 for 6 MV
and
bull 0953 plusmn 0004 for 15 MV
Reduction of dose at isocenter
due to 8mm of PMMA
By measuring the attenuation
factor the output value can be
corrected
Attenuation of the beam by the DAVID chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg25
100 cm SSDIncreased about
032 with DAVID
No change of
Dmax
14 cm with
and without DAVID
80 cm SSD
An increased about
426 with DAVID
slight change of
Dmax
13 cm with DAVID
14 cm without DAVID
IV ResultsDiscussion Changes in PDD
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg26
100 cm SSD
An increased about
067 with DAVID
Dmax
26 cm No change
80 cm SSD
An increased about
18 with DAVID
slight change of
Dmax
18 cm with DAVID
24 cm without DAVID
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg27
Surface dose
Increase with increase in field size
Increase with increase in energy
Increase with decrease in SSD
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg28
Pronounce with
decrease in SSD and
increase in photon energy and
increase in field size
Increase in surface dose is
due to scattered secondary
electrons from the DAVID
chamber reaching the
water phantom surface
(electron contamination)
6 cm
45 cm
100 cm
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg29
Deconvolution test
by iteration method
IV ResultsDiscussion Deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg15
DAVID Analysis
bull PTW DAVID 20 software
III Materials amp Methods
Warning level 3
Alarm level 5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg16
III Materials amp Methods
bullVMAT 4 (1 HampN 3 Prostates)
bull180deg to -180deg Clockwise and anti clockwise
Stability of the DAVID system
bullIMRT 1 (Prostate)
bull0deg
bull90deg
bull270deg
(Prostate and Head and Neck) 14 days
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg17
III Materials amp MethodsThe beam property of the DAVID chamber
bullPercentage depth dose (PDD)
bullRoos chamber 34001
bullMP3 water phantom
bullTransmission factor for 6 and 15 MV
bullSemifex T31010 (Diff Field sizes)
Setup conditions
bull With and without DAVID
bull SSD 100 and 80 cm
bull Photon energy 6 and 15
MV
bull Different field sizes
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg18
1 Successive opening of 1 leaf on 1
side
III Materials amp MethodsVMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg19
1 Successive opening of 1 leaf on 1
side
VMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
III Materials amp Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg20
DeconvolutionIII Materials amp Methods
S(x) measured signal as convolution of
P(x) True bdquodoseldquo profile with
LRF fɛ(x)
S(x) = P(x) f(x)
bdquovan Cittertldquo iterative deconvolution
algorithm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg21
opened MLC at every 10th interval from 1st to 80th
pairs
Nine MLC slit through the entire DAVID chamber
IV Results and Discussion Alignment
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg22
IV Results and Discussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT prostate
bull Deviation of plusmn1 (-1)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg23
IV ResultsDiscussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT HampN
bull Deviation of lt05
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg24
IV ResultsDiscussion Transmission factor
The average KDAVID
bull 0939 plusmn0003 for 6 MV
and
bull 0953 plusmn 0004 for 15 MV
Reduction of dose at isocenter
due to 8mm of PMMA
By measuring the attenuation
factor the output value can be
corrected
Attenuation of the beam by the DAVID chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg25
100 cm SSDIncreased about
032 with DAVID
No change of
Dmax
14 cm with
and without DAVID
80 cm SSD
An increased about
426 with DAVID
slight change of
Dmax
13 cm with DAVID
14 cm without DAVID
IV ResultsDiscussion Changes in PDD
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg26
100 cm SSD
An increased about
067 with DAVID
Dmax
26 cm No change
80 cm SSD
An increased about
18 with DAVID
slight change of
Dmax
18 cm with DAVID
24 cm without DAVID
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg27
Surface dose
Increase with increase in field size
Increase with increase in energy
Increase with decrease in SSD
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg28
Pronounce with
decrease in SSD and
increase in photon energy and
increase in field size
Increase in surface dose is
due to scattered secondary
electrons from the DAVID
chamber reaching the
water phantom surface
(electron contamination)
6 cm
45 cm
100 cm
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg29
Deconvolution test
by iteration method
IV ResultsDiscussion Deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg16
III Materials amp Methods
bullVMAT 4 (1 HampN 3 Prostates)
bull180deg to -180deg Clockwise and anti clockwise
Stability of the DAVID system
bullIMRT 1 (Prostate)
bull0deg
bull90deg
bull270deg
(Prostate and Head and Neck) 14 days
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg17
III Materials amp MethodsThe beam property of the DAVID chamber
bullPercentage depth dose (PDD)
bullRoos chamber 34001
bullMP3 water phantom
bullTransmission factor for 6 and 15 MV
bullSemifex T31010 (Diff Field sizes)
Setup conditions
bull With and without DAVID
bull SSD 100 and 80 cm
bull Photon energy 6 and 15
MV
bull Different field sizes
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg18
1 Successive opening of 1 leaf on 1
side
III Materials amp MethodsVMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg19
1 Successive opening of 1 leaf on 1
side
VMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
III Materials amp Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg20
DeconvolutionIII Materials amp Methods
S(x) measured signal as convolution of
P(x) True bdquodoseldquo profile with
LRF fɛ(x)
S(x) = P(x) f(x)
bdquovan Cittertldquo iterative deconvolution
algorithm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg21
opened MLC at every 10th interval from 1st to 80th
pairs
Nine MLC slit through the entire DAVID chamber
IV Results and Discussion Alignment
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg22
IV Results and Discussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT prostate
bull Deviation of plusmn1 (-1)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg23
IV ResultsDiscussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT HampN
bull Deviation of lt05
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg24
IV ResultsDiscussion Transmission factor
The average KDAVID
bull 0939 plusmn0003 for 6 MV
and
bull 0953 plusmn 0004 for 15 MV
Reduction of dose at isocenter
due to 8mm of PMMA
By measuring the attenuation
factor the output value can be
corrected
Attenuation of the beam by the DAVID chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg25
100 cm SSDIncreased about
032 with DAVID
No change of
Dmax
14 cm with
and without DAVID
80 cm SSD
An increased about
426 with DAVID
slight change of
Dmax
13 cm with DAVID
14 cm without DAVID
IV ResultsDiscussion Changes in PDD
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg26
100 cm SSD
An increased about
067 with DAVID
Dmax
26 cm No change
80 cm SSD
An increased about
18 with DAVID
slight change of
Dmax
18 cm with DAVID
24 cm without DAVID
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg27
Surface dose
Increase with increase in field size
Increase with increase in energy
Increase with decrease in SSD
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg28
Pronounce with
decrease in SSD and
increase in photon energy and
increase in field size
Increase in surface dose is
due to scattered secondary
electrons from the DAVID
chamber reaching the
water phantom surface
(electron contamination)
6 cm
45 cm
100 cm
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg29
Deconvolution test
by iteration method
IV ResultsDiscussion Deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg17
III Materials amp MethodsThe beam property of the DAVID chamber
bullPercentage depth dose (PDD)
bullRoos chamber 34001
bullMP3 water phantom
bullTransmission factor for 6 and 15 MV
bullSemifex T31010 (Diff Field sizes)
Setup conditions
bull With and without DAVID
bull SSD 100 and 80 cm
bull Photon energy 6 and 15
MV
bull Different field sizes
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg18
1 Successive opening of 1 leaf on 1
side
III Materials amp MethodsVMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg19
1 Successive opening of 1 leaf on 1
side
VMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
III Materials amp Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg20
DeconvolutionIII Materials amp Methods
S(x) measured signal as convolution of
P(x) True bdquodoseldquo profile with
LRF fɛ(x)
S(x) = P(x) f(x)
bdquovan Cittertldquo iterative deconvolution
algorithm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg21
opened MLC at every 10th interval from 1st to 80th
pairs
Nine MLC slit through the entire DAVID chamber
IV Results and Discussion Alignment
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg22
IV Results and Discussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT prostate
bull Deviation of plusmn1 (-1)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg23
IV ResultsDiscussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT HampN
bull Deviation of lt05
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg24
IV ResultsDiscussion Transmission factor
The average KDAVID
bull 0939 plusmn0003 for 6 MV
and
bull 0953 plusmn 0004 for 15 MV
Reduction of dose at isocenter
due to 8mm of PMMA
By measuring the attenuation
factor the output value can be
corrected
Attenuation of the beam by the DAVID chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg25
100 cm SSDIncreased about
032 with DAVID
No change of
Dmax
14 cm with
and without DAVID
80 cm SSD
An increased about
426 with DAVID
slight change of
Dmax
13 cm with DAVID
14 cm without DAVID
IV ResultsDiscussion Changes in PDD
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg26
100 cm SSD
An increased about
067 with DAVID
Dmax
26 cm No change
80 cm SSD
An increased about
18 with DAVID
slight change of
Dmax
18 cm with DAVID
24 cm without DAVID
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg27
Surface dose
Increase with increase in field size
Increase with increase in energy
Increase with decrease in SSD
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg28
Pronounce with
decrease in SSD and
increase in photon energy and
increase in field size
Increase in surface dose is
due to scattered secondary
electrons from the DAVID
chamber reaching the
water phantom surface
(electron contamination)
6 cm
45 cm
100 cm
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg29
Deconvolution test
by iteration method
IV ResultsDiscussion Deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg18
1 Successive opening of 1 leaf on 1
side
III Materials amp MethodsVMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg19
1 Successive opening of 1 leaf on 1
side
VMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
III Materials amp Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg20
DeconvolutionIII Materials amp Methods
S(x) measured signal as convolution of
P(x) True bdquodoseldquo profile with
LRF fɛ(x)
S(x) = P(x) f(x)
bdquovan Cittertldquo iterative deconvolution
algorithm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg21
opened MLC at every 10th interval from 1st to 80th
pairs
Nine MLC slit through the entire DAVID chamber
IV Results and Discussion Alignment
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg22
IV Results and Discussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT prostate
bull Deviation of plusmn1 (-1)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg23
IV ResultsDiscussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT HampN
bull Deviation of lt05
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg24
IV ResultsDiscussion Transmission factor
The average KDAVID
bull 0939 plusmn0003 for 6 MV
and
bull 0953 plusmn 0004 for 15 MV
Reduction of dose at isocenter
due to 8mm of PMMA
By measuring the attenuation
factor the output value can be
corrected
Attenuation of the beam by the DAVID chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg25
100 cm SSDIncreased about
032 with DAVID
No change of
Dmax
14 cm with
and without DAVID
80 cm SSD
An increased about
426 with DAVID
slight change of
Dmax
13 cm with DAVID
14 cm without DAVID
IV ResultsDiscussion Changes in PDD
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg26
100 cm SSD
An increased about
067 with DAVID
Dmax
26 cm No change
80 cm SSD
An increased about
18 with DAVID
slight change of
Dmax
18 cm with DAVID
24 cm without DAVID
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg27
Surface dose
Increase with increase in field size
Increase with increase in energy
Increase with decrease in SSD
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg28
Pronounce with
decrease in SSD and
increase in photon energy and
increase in field size
Increase in surface dose is
due to scattered secondary
electrons from the DAVID
chamber reaching the
water phantom surface
(electron contamination)
6 cm
45 cm
100 cm
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg29
Deconvolution test
by iteration method
IV ResultsDiscussion Deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg19
1 Successive opening of 1 leaf on 1
side
VMAT Plan Editing for error detection
bull MATLAB script to change the MLC-positions
3 Field shift of a leaf gap (size of leave
gap remains)
2 Successive shift of a leaf gap (size of
leave gap remains)
III Materials amp Methods
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg20
DeconvolutionIII Materials amp Methods
S(x) measured signal as convolution of
P(x) True bdquodoseldquo profile with
LRF fɛ(x)
S(x) = P(x) f(x)
bdquovan Cittertldquo iterative deconvolution
algorithm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg21
opened MLC at every 10th interval from 1st to 80th
pairs
Nine MLC slit through the entire DAVID chamber
IV Results and Discussion Alignment
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg22
IV Results and Discussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT prostate
bull Deviation of plusmn1 (-1)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg23
IV ResultsDiscussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT HampN
bull Deviation of lt05
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg24
IV ResultsDiscussion Transmission factor
The average KDAVID
bull 0939 plusmn0003 for 6 MV
and
bull 0953 plusmn 0004 for 15 MV
Reduction of dose at isocenter
due to 8mm of PMMA
By measuring the attenuation
factor the output value can be
corrected
Attenuation of the beam by the DAVID chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg25
100 cm SSDIncreased about
032 with DAVID
No change of
Dmax
14 cm with
and without DAVID
80 cm SSD
An increased about
426 with DAVID
slight change of
Dmax
13 cm with DAVID
14 cm without DAVID
IV ResultsDiscussion Changes in PDD
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg26
100 cm SSD
An increased about
067 with DAVID
Dmax
26 cm No change
80 cm SSD
An increased about
18 with DAVID
slight change of
Dmax
18 cm with DAVID
24 cm without DAVID
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg27
Surface dose
Increase with increase in field size
Increase with increase in energy
Increase with decrease in SSD
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg28
Pronounce with
decrease in SSD and
increase in photon energy and
increase in field size
Increase in surface dose is
due to scattered secondary
electrons from the DAVID
chamber reaching the
water phantom surface
(electron contamination)
6 cm
45 cm
100 cm
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg29
Deconvolution test
by iteration method
IV ResultsDiscussion Deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg20
DeconvolutionIII Materials amp Methods
S(x) measured signal as convolution of
P(x) True bdquodoseldquo profile with
LRF fɛ(x)
S(x) = P(x) f(x)
bdquovan Cittertldquo iterative deconvolution
algorithm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg21
opened MLC at every 10th interval from 1st to 80th
pairs
Nine MLC slit through the entire DAVID chamber
IV Results and Discussion Alignment
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg22
IV Results and Discussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT prostate
bull Deviation of plusmn1 (-1)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg23
IV ResultsDiscussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT HampN
bull Deviation of lt05
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg24
IV ResultsDiscussion Transmission factor
The average KDAVID
bull 0939 plusmn0003 for 6 MV
and
bull 0953 plusmn 0004 for 15 MV
Reduction of dose at isocenter
due to 8mm of PMMA
By measuring the attenuation
factor the output value can be
corrected
Attenuation of the beam by the DAVID chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg25
100 cm SSDIncreased about
032 with DAVID
No change of
Dmax
14 cm with
and without DAVID
80 cm SSD
An increased about
426 with DAVID
slight change of
Dmax
13 cm with DAVID
14 cm without DAVID
IV ResultsDiscussion Changes in PDD
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg26
100 cm SSD
An increased about
067 with DAVID
Dmax
26 cm No change
80 cm SSD
An increased about
18 with DAVID
slight change of
Dmax
18 cm with DAVID
24 cm without DAVID
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg27
Surface dose
Increase with increase in field size
Increase with increase in energy
Increase with decrease in SSD
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg28
Pronounce with
decrease in SSD and
increase in photon energy and
increase in field size
Increase in surface dose is
due to scattered secondary
electrons from the DAVID
chamber reaching the
water phantom surface
(electron contamination)
6 cm
45 cm
100 cm
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg29
Deconvolution test
by iteration method
IV ResultsDiscussion Deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg21
opened MLC at every 10th interval from 1st to 80th
pairs
Nine MLC slit through the entire DAVID chamber
IV Results and Discussion Alignment
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg22
IV Results and Discussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT prostate
bull Deviation of plusmn1 (-1)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg23
IV ResultsDiscussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT HampN
bull Deviation of lt05
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg24
IV ResultsDiscussion Transmission factor
The average KDAVID
bull 0939 plusmn0003 for 6 MV
and
bull 0953 plusmn 0004 for 15 MV
Reduction of dose at isocenter
due to 8mm of PMMA
By measuring the attenuation
factor the output value can be
corrected
Attenuation of the beam by the DAVID chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg25
100 cm SSDIncreased about
032 with DAVID
No change of
Dmax
14 cm with
and without DAVID
80 cm SSD
An increased about
426 with DAVID
slight change of
Dmax
13 cm with DAVID
14 cm without DAVID
IV ResultsDiscussion Changes in PDD
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg26
100 cm SSD
An increased about
067 with DAVID
Dmax
26 cm No change
80 cm SSD
An increased about
18 with DAVID
slight change of
Dmax
18 cm with DAVID
24 cm without DAVID
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg27
Surface dose
Increase with increase in field size
Increase with increase in energy
Increase with decrease in SSD
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg28
Pronounce with
decrease in SSD and
increase in photon energy and
increase in field size
Increase in surface dose is
due to scattered secondary
electrons from the DAVID
chamber reaching the
water phantom surface
(electron contamination)
6 cm
45 cm
100 cm
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg29
Deconvolution test
by iteration method
IV ResultsDiscussion Deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg22
IV Results and Discussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT prostate
bull Deviation of plusmn1 (-1)
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg23
IV ResultsDiscussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT HampN
bull Deviation of lt05
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg24
IV ResultsDiscussion Transmission factor
The average KDAVID
bull 0939 plusmn0003 for 6 MV
and
bull 0953 plusmn 0004 for 15 MV
Reduction of dose at isocenter
due to 8mm of PMMA
By measuring the attenuation
factor the output value can be
corrected
Attenuation of the beam by the DAVID chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg25
100 cm SSDIncreased about
032 with DAVID
No change of
Dmax
14 cm with
and without DAVID
80 cm SSD
An increased about
426 with DAVID
slight change of
Dmax
13 cm with DAVID
14 cm without DAVID
IV ResultsDiscussion Changes in PDD
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg26
100 cm SSD
An increased about
067 with DAVID
Dmax
26 cm No change
80 cm SSD
An increased about
18 with DAVID
slight change of
Dmax
18 cm with DAVID
24 cm without DAVID
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg27
Surface dose
Increase with increase in field size
Increase with increase in energy
Increase with decrease in SSD
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg28
Pronounce with
decrease in SSD and
increase in photon energy and
increase in field size
Increase in surface dose is
due to scattered secondary
electrons from the DAVID
chamber reaching the
water phantom surface
(electron contamination)
6 cm
45 cm
100 cm
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg29
Deconvolution test
by iteration method
IV ResultsDiscussion Deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg23
IV ResultsDiscussion Stability of DAVID System
bull IMRT prostate
bull Deviation of plusmn2 (+2)
bull VMAT HampN
bull Deviation of lt05
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg24
IV ResultsDiscussion Transmission factor
The average KDAVID
bull 0939 plusmn0003 for 6 MV
and
bull 0953 plusmn 0004 for 15 MV
Reduction of dose at isocenter
due to 8mm of PMMA
By measuring the attenuation
factor the output value can be
corrected
Attenuation of the beam by the DAVID chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg25
100 cm SSDIncreased about
032 with DAVID
No change of
Dmax
14 cm with
and without DAVID
80 cm SSD
An increased about
426 with DAVID
slight change of
Dmax
13 cm with DAVID
14 cm without DAVID
IV ResultsDiscussion Changes in PDD
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg26
100 cm SSD
An increased about
067 with DAVID
Dmax
26 cm No change
80 cm SSD
An increased about
18 with DAVID
slight change of
Dmax
18 cm with DAVID
24 cm without DAVID
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg27
Surface dose
Increase with increase in field size
Increase with increase in energy
Increase with decrease in SSD
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg28
Pronounce with
decrease in SSD and
increase in photon energy and
increase in field size
Increase in surface dose is
due to scattered secondary
electrons from the DAVID
chamber reaching the
water phantom surface
(electron contamination)
6 cm
45 cm
100 cm
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg29
Deconvolution test
by iteration method
IV ResultsDiscussion Deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg24
IV ResultsDiscussion Transmission factor
The average KDAVID
bull 0939 plusmn0003 for 6 MV
and
bull 0953 plusmn 0004 for 15 MV
Reduction of dose at isocenter
due to 8mm of PMMA
By measuring the attenuation
factor the output value can be
corrected
Attenuation of the beam by the DAVID chamber
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg25
100 cm SSDIncreased about
032 with DAVID
No change of
Dmax
14 cm with
and without DAVID
80 cm SSD
An increased about
426 with DAVID
slight change of
Dmax
13 cm with DAVID
14 cm without DAVID
IV ResultsDiscussion Changes in PDD
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg26
100 cm SSD
An increased about
067 with DAVID
Dmax
26 cm No change
80 cm SSD
An increased about
18 with DAVID
slight change of
Dmax
18 cm with DAVID
24 cm without DAVID
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg27
Surface dose
Increase with increase in field size
Increase with increase in energy
Increase with decrease in SSD
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg28
Pronounce with
decrease in SSD and
increase in photon energy and
increase in field size
Increase in surface dose is
due to scattered secondary
electrons from the DAVID
chamber reaching the
water phantom surface
(electron contamination)
6 cm
45 cm
100 cm
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg29
Deconvolution test
by iteration method
IV ResultsDiscussion Deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg25
100 cm SSDIncreased about
032 with DAVID
No change of
Dmax
14 cm with
and without DAVID
80 cm SSD
An increased about
426 with DAVID
slight change of
Dmax
13 cm with DAVID
14 cm without DAVID
IV ResultsDiscussion Changes in PDD
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg26
100 cm SSD
An increased about
067 with DAVID
Dmax
26 cm No change
80 cm SSD
An increased about
18 with DAVID
slight change of
Dmax
18 cm with DAVID
24 cm without DAVID
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg27
Surface dose
Increase with increase in field size
Increase with increase in energy
Increase with decrease in SSD
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg28
Pronounce with
decrease in SSD and
increase in photon energy and
increase in field size
Increase in surface dose is
due to scattered secondary
electrons from the DAVID
chamber reaching the
water phantom surface
(electron contamination)
6 cm
45 cm
100 cm
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg29
Deconvolution test
by iteration method
IV ResultsDiscussion Deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg26
100 cm SSD
An increased about
067 with DAVID
Dmax
26 cm No change
80 cm SSD
An increased about
18 with DAVID
slight change of
Dmax
18 cm with DAVID
24 cm without DAVID
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg27
Surface dose
Increase with increase in field size
Increase with increase in energy
Increase with decrease in SSD
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg28
Pronounce with
decrease in SSD and
increase in photon energy and
increase in field size
Increase in surface dose is
due to scattered secondary
electrons from the DAVID
chamber reaching the
water phantom surface
(electron contamination)
6 cm
45 cm
100 cm
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg29
Deconvolution test
by iteration method
IV ResultsDiscussion Deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg27
Surface dose
Increase with increase in field size
Increase with increase in energy
Increase with decrease in SSD
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg28
Pronounce with
decrease in SSD and
increase in photon energy and
increase in field size
Increase in surface dose is
due to scattered secondary
electrons from the DAVID
chamber reaching the
water phantom surface
(electron contamination)
6 cm
45 cm
100 cm
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg29
Deconvolution test
by iteration method
IV ResultsDiscussion Deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg28
Pronounce with
decrease in SSD and
increase in photon energy and
increase in field size
Increase in surface dose is
due to scattered secondary
electrons from the DAVID
chamber reaching the
water phantom surface
(electron contamination)
6 cm
45 cm
100 cm
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg29
Deconvolution test
by iteration method
IV ResultsDiscussion Deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg29
Deconvolution test
by iteration method
IV ResultsDiscussion Deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg30
Deconvolution
bulldoes not depend on the length of the slit
bull40 cm slit results showed a small decrease in the tail signals
10 x 10 cm
10 cm slit
40 cm slit
20 cm slit
30 cm slit
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
31
IV ResultsDiscussion
Deconvoluted slit signal at 40th and 65th wire
Deconvolution test
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
32
10x10cm fields before and after deconvolution
Single arc prostate plan before and after deconvolution (3 mm )
IV ResultsDiscussion Deconvolution with DAVID software
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
33
before deconvolution 61 mm
Gradients of the linear fit
before deconvolution 047 and
after deconvolution 29 mm
Gradients of the linear fit
after deconvolution 094
IV ResultsDiscussion Enhance sensitivity after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
34
before deconvolution after deconvolution
HampN 6mm error
IV ResultsDiscussion
False alarmwarning effect before deconvolution
The effect is eliminated after deconvolution
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
35
Undeconvoluted
deconvoluted
Measuring the deconvolution matrix with
the DAVID software as manual LSF of single middle slit is measured and
used to generate the 80x80 LRF matrix with
MAT LAB and installed in the DAVID software
for deconvolution
IV ResultsDiscussion Limitations of DAVID-160 system
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
36
2mm MLC error single bank shift2mm MLC error single leaf
Analyzing both the maximum deviation
and total deviation in two different plots
at the same time
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
37
Max Dose 7599GyMax Dose 5727Gc
IV ResultsDiscussion Artificial MLC bang shift Error 2
cm
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg38
0
1
2
3
4
5
6
7
8
0 8 10 12 14 16 18 20
shift mm
dose
in
cre
ase
G
y
ma
xim
al d
evia
tio
n
Undetectable error Design of the chamber
DAVID Gap-Shift (prostate with OAR rectum back wall)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
39
DAVID Quality Assurance software (DQA)
MAT LAB 2011b and 2012b
analyzes the daily session for all patients data with 2 clicks online
bull NDD- Non deconvoluted data
bull DD-Deconvoluted data
bull ED- Electrical data
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
40
Analysis only specific data on
specific date session and only print
out the deconvoluted data (DD)
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
41
Patient text file from DQA software
Sample patient 2014-01-12
Display only datas with MLC error
indicating the data type (DD)Beam
number Session segment and
particular MLC with error
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
42
The DQA software displays the warning and alarm errors
Warning and error dialogs at future date entry and invalid date entry respectively
year-month-day `yyyy-mm-dd
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
43
VMAT and IMRT plans sessions
IV ResultsDiscussion
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg44
DAVID chamber
bull Linear dependency on leaf opening
bull Sensitivity dependent on leaf gap opening
bull How much radiation pass through the opening
bull Deconvolution double the sensitivity
DAVID is design for specifics LINACS
Independent from the LINAC
In-vivo verification of MLC malfunction during VMAT
bull Undetectability field shifts due to chamber design
(Suggestion perpendicular wires or gradient)
V Conclusions
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg45
V Conclusion
Single MLC bank shift error
Maximum and total deviation to be analysed
Deconvolution matrix
To be generated for each linac
To be generated by single single slit
bull In comparison to other techniques measurement of undisturbed
signals
-gt no dependence on patient position(EPID)
-gt measurement of the complete delivered dose(TLD diode or MOSFET
detectors)
bull Suggestions for future development Standard design for software
bull Deconvolution program to be integrated
bull DQA to be integrated
bull Design two chambers perpendicular to each other
Co-operate directly with LINAC vendors for specifics designs
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg46
Sources
1 [1] Ezzel GA Galvin JM Low D Palta JR Rosen I Sharpe MB Xia P Xiao Y Xing L and Yu CX Guidance on delivery
treatment planning and clinical implementation of IMRT report of the IMRT subcommittee of the AAPM radiation
therapy committee Med Phys 2003 302089-115
2 [2] ESTRO Booklet No 9 2008 Guidelines for the verification of IMRT edited by Ben Mijnheer and Dietmar Georg
ISBN 90-804532-9
3 [3] Schneider F Polednik M Wol D Steil V Delana A Wenz F Menegotti L Optimization of the gafchromic EBT
protocol for IMRT QA Z Med Phys 2009 19(1)29-37
4 [4] Poppe B Blechschmidt A Djouguela A Kollho R Rubach A and Harder D Two-dimensional ionisation-chamber
arrays for IMRT plan verication Med Phys 2006 331005-15
5 [5] Poppe B Thieke C Beyer D Kollho R Djouguela A Ruumlhmann A Willborn KC and Harder D DAVID-a translucent
multi-wire transmission ionization chamber for in vivo verication of IMRT and conformal irradiation techniques Phys
Med Biol 2006 511237-48
6 [9] Poppe B Looe H K Chofor N Ruumlhmann A Harder D and Willborn K Clinical Performance of a Transmission
Detector Array for the Permanent Supervision of IMRT Deliveries Radiother Oncol 2010 95158-65
7 [10] Looe H K Harder D Ruumlhmann A Willborn K and Poppe B Enhanced accuracy of the permanent surveillance of
IMRT deliveries by iterative deconvolution of DAVID chamber signal proles Phys Med Biol 2010 553981-92
8 [11] Heukelom S el alWedge factor constituents of high-energy photon beams Head and phantom scatter dose
components Radiother Oncol 32 (1994) 66-3
9 12] Jursinic P A Changes in incident photon uence of 6 and 18 MV x rays caused by blocks and block trays Med
Phys 26 (1999) 2092-8
10 [13] v Klevens H Dependence of the tray transmission factor on collimator setting and sourcesurface distance Med
Phys 27 (2000) 2117-3
11 [14] Sharma SC el al Recommendations for measurement of tray and wedge factors for high energy photons Med
Phys 21 (1994) 573-5
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg47
Thank you for your
attention
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg48
Additional Slides
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
49
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
Description of the Elekta synergy DAVID160 system
50
David58
David160
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
51
bullΦ constant with depth
(small interactions)
bullSame electrons set in
motion in each square
bullie interactions per
volume constant through
target
bulldose reaches a
maximum at R (kerma
constant with depth
equals absorbed dose
beyond )
Number of electron tracks set in motion by
photon interaction
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
52
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
53
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
54
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
55
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56
WG Medical Radiation Physics Pius-Hospital and Carl von Ossietzky University Oldenburg
56