TG51_figures.pdf
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Transcript of TG51_figures.pdf
AAPM’s TG–51 Protocol for Clinical Reference Dosimetry of
High-Energy Photon and Electron Beams
Peter R. Almond,Brown Cancer Center,Louisville, KY 40202
Peter J. Biggs,Department of Radiation Oncology, Massachusetts General Hospital,
Boston, MA 02114B.M. Coursey,
Ionizing Radiation Division, National Institute of Standards and Technology,Gaithersburg, MD 20899
W.F. Hanson,M.D. Anderson Cancer Center, University of Texas, Houston, TX 77030
M.Saiful Huq,Kimmel Cancer Center of Jefferson Medical College,Thomas Jefferson University, Philadelphia, PA 19107
Ravinder Nath,Yale Univ School of Medicine,New Haven, CT 06510
D.W.O. Rogers,Ionizing Radiation Standards, National Research Council of Canada,
Ottawa K1A OR6, Canada
∗ Developed by TG–51 of the Radiation Therapy Committee of the AAPM.
As published in Med Phys 26 (1999) 1847 – 1870
Abstract
This is the figures from TG-51 in a large scale and colour format. Note the postscript and/orpdf versions available at http://www.irs.inms.nrc.ca/inms/irs/tg51 figures/tg51 figures.html
1
AAPM’s TG–51 Protocol for Reference Dosimetry: Med Phys 26 (1999) 1847 – 1870 page 2
0 5 10 15 20depth /cm
50
60
70
80
90
100
%de
pth−
ioni
zatio
n
dmax A
I
II
%dd(10)
0 1 2 3 4 5 6 7 8depth / cm
0
20
40
60
80
100
I
II
a)b)
B
dose
I50
Figure 1: Effect of shifting depth-ionization data measured with cylindrical chambers upstream by0.6 rcav for photon beams (panel a) and 0.5 rcav for electron beams (panel b) (with rcav = 1.0 cm).The raw data are shown by curve I (long dashes) in both cases and the shifted data, which are takenas the depth-ionization curve, are shown by curve II (solid line). The value of the % ionization atpoint A (10 cm depth) in the photon beam gives %dd(10) and the depth at point B (solid curve, 50%ionization) in the electron beam gives I50 from which R50 can be determined (see section VIII.C). Forthe photon beams, curve II is effectively the percentage depth-dose curve. For the electron beams,curve II must be further corrected (see section X.D) to obtain the percentage depth-dose curve shown(short dashes - but this is not needed for application of the protocol).
∼dave/tex/tg51/tg51.tex: Edited 18 Aug 1999
AAPM’s TG–51 Protocol for Reference Dosimetry: Med Phys 26 (1999) 1847 – 1870 page 3
0 2 4 6 8 10 12depth /cm
0
10
20
30
40
50
60
70
80
90
100
110
% d
epth
−do
se
dd_R50_dref
dmax
R50
dref = 0.6 R50 − 0.1 cm
Figure 2: R50 is defined as the depth, in cm, at which the absorbed dose falls to 50% of its maximumvalue in a ≥ 10 × 10 cm2 (≥ 20 × 20 cm2 for R50 > 8.5 cm) electron beam at an SSD of 100 cm.The depth for clinical reference dosimetry is dref = 0.6R50 − 0.1 cm, in the same sized beam at anSSD between 90 and 110 cm. Note that for low-energy beams, dref is usually at dmax.
∼dave/tex/tg51/tg51.tex: Edited 18 Aug 1999
AAPM’s TG–51 Protocol for Reference Dosimetry: Med Phys 26 (1999) 1847 – 1870 page 4
� � � � � � � � � � � � �� � � � � � � � � � � � �� � � � � � � � � � � � �
SAD Setup
10 cm
10x10 10 cm
SSD
10x10
SSD Setup
� � � � � � � � � � � � �� � � � � � � � � � � � �� � � � � � � � � � � � �
SAD
Figure 3: Schematic of the SSD or SAD setups which may be used for photon beam referencedosimetry. In both cases the ion chamber is at a water equivalent depth of 10 cm in the waterphantom. The actual value of SSD or SAD is that most useful in the clinic (expected to be about100 cm).
∼dave/tex/tg51/tg51.tex: Edited 18 Aug 1999
AAPM’s TG–51 Protocol for Reference Dosimetry: Med Phys 26 (1999) 1847 – 1870 page 5
55 60 65 70 75 80 85 90%dd(10)X
0.94
0.95
0.96
0.97
0.98
0.99
1.00
k Q
kQ_photon
A12,A1,PR05,PR05P,IC−5,IC−10
NE2561PR06C
NE2581
PTW N30002
PTW N30001,31003
NE2571, 25772505/3A, 30004
Figure 4: Values of kQ at 10 cm depth in accelerator photon beams as a function of %dd(10)x forcylindrical ion chambers commonly used for clinical reference dosimetry. When values were the samewithin 0.1%, only one curve is shown. Explicit values are given in Table I, as is a list of equivalentchambers. For 60Co beams, kQ = 1.000.
∼dave/tex/tg51/tg51.tex: Edited 18 Aug 1999
AAPM’s TG–51 Protocol for Reference Dosimetry: Med Phys 26 (1999) 1847 – 1870 page 6
2 3 4 5 6 7 8 9R50 /cm
1.00
1.01
1.02
1.03
k’ R
50 a
t dre
f
kR50.prime
N23331
N30001
A12
NE2505.3A NE2571
NE2581PR06C/G
N30002IC10/5
N31003
PR06C/G
0.9905+0.071e(−R50/3.67)
NE2577 N30004
Exradin A1,PR05,PR05P
NE2561
Figure 5: Calculated values of k′R50at dref as a function of R50 for several common cylindrical ion
chambers. These values can be used with Eq.(6), (with a measured value of PQgr and a kecal value
from Table III) to determine the absorbed dose to water at the reference depth of dref = 0.6R50− 0.1cm.
∼dave/tex/tg51/tg51.tex: Edited 18 Aug 1999
AAPM’s TG–51 Protocol for Reference Dosimetry: Med Phys 26 (1999) 1847 – 1870 page 7
2 3 4 5 6 7 8 9R50 /cm
0.99
1.00
1.01
1.02
1.03
1.04
1.05
1.06
k’ R
50 a
t dre
f
Attix
Exradin P11
Markus
NACP
PTB/Roos
kQ.prime_pp
Holt
Capintec
kR50.prime_pp
1.2239−0.145(R50)0.214
Figure 6: Calculated values of k′R50at dref as a function of R50 for several common plane-parallel cham-
bers. Note that the values for the 5 well-guarded chambers lie on the same line in the figure. Thesevalues can be used with Eq.(6) (with PQ
gr = 1.0) to determine the absorbed dose to water at thereference depth of dref = 0.6R50 − 0.1 cm.
∼dave/tex/tg51/tg51.tex: Edited 18 Aug 1999
AAPM’s TG–51 Protocol for Reference Dosimetry: Med Phys 26 (1999) 1847 – 1870 page 8
9 10 11 12 13 14 15 16 17 18 19 20R50 /cm
0.96
0.97
0.98
0.99
1.00
k’ R
50 a
t dre
f
kR50.prime
N30002A12
A12
NE2505.3ANE2571
NE2581PR06C/G
N30002IC10/15
NE2581PR06C/G
NE2505.3A NE2571 NE2577N30001
N30004
NE2581 PR06C/G
NE2561 N23331
IC10/5
N31003
Exradin A1,PR05,PR05P
Figure 7: Calculated values of k′R50at dref for high-energy electron beams, as a function of R50 for
cylindrical ion chambers. These values can be used with Eq.(6), (with a measured value of PQgr
and a kecal value from Table III) to determine the absorbed dose to water at the reference depth ofdref = 0.6R50 − 0.1 cm.
∼dave/tex/tg51/tg51.tex: Edited 18 Aug 1999
AAPM’s TG–51 Protocol for Reference Dosimetry: Med Phys 26 (1999) 1847 – 1870 page 9
9 10 11 12 13 14 15 16 17 18 19 20R50 /cm
0.95
0.96
0.97
0.98
0.99
1.00
k
’ R50
at d
ref
Attix
Exradin P11 Markus
NACP
PTB/Roos
kQ.prime_pp
’
Holt
Capintec
’
1.2239−0.145(R50)0.214
kR50.prime_pp.high
Figure 8: Calculated values of k′R50at dref for high-energy electron beams, as a function of R50 for
plane-parallel chambers. Note that the values for the 5 well-guarded chambers lie on the same linein the figure. These values can be used with Eq.(6) (with PQ
gr = 1.0 and a kecal value from Table II)to determine the absorbed dose to water at the reference depth of dref = 0.6R50 − 0.1 cm.
∼dave/tex/tg51/tg51.tex: Edited 18 Aug 1999