Applications of the mathematical Applications of the mathematical Applications of the mathematical Applications of the mathematical model model model model ---- examples that satisfy examples that satisfy examples that satisfy examples that satisfy

ISOISOISOISO----11137 requirements 11137 requirements 11137 requirements 11137 requirements

Kevin P.J. O’HaraSenior Radiation Physicist

MDS Nordion

Agenda Agenda Agenda Agenda Dose Calculation Applications within ISO 11137Dose Calculation Applications within ISO 11137Dose Calculation Applications within ISO 11137Dose Calculation Applications within ISO 11137

• Historical requirements for dosimetry– OQ, PQ and routine monitoring

• Some applications of mathematical modelling– Irradiator Design, Evaluation of cobalt source loadings,

Impact of partial product stacks, Effect of process interruption, Assessment of irradiator change

• V&V of the mathematical model– Ensure that model and overall quality management system

is ready for a regulatory audit. • Evaluation of complicated medical devices with the

model

International Organizations that International Organizations that International Organizations that International Organizations that Promote the Mathematical ModelPromote the Mathematical ModelPromote the Mathematical ModelPromote the Mathematical Model

www.rpsmug.org

www.astm.org

www.irradiationpanel.org

Software PlanSoftware PlanSoftware PlanSoftware PlanQuality System RequirementsQuality System RequirementsQuality System RequirementsQuality System RequirementsPrePrePrePre----requisites for Applicationrequisites for Applicationrequisites for Applicationrequisites for Application

• Software written and tested including,– Functional Description, Design Review Requirements,

Version and Access Control, Hazard/Safety Analysis Source Code Review, Training, User’s Manual, and…

Model Benchmarking Model Benchmarking Model Benchmarking Model Benchmarking –––– over full range of applicationsover full range of applicationsover full range of applicationsover full range of applications

� Completion is imperative before the routine use� Validate the overall model construction and underlying

physics, and verify the mathematical method � Compare model predictions to independent measurements

or calculations

Defining the Irradiator GeometryDefining the Irradiator GeometryDefining the Irradiator GeometryDefining the Irradiator Geometry

Alanine Results4 pass, 0.183 g/cc

19.5

20.0

20.5

21.0

21.5

22.0

22.5

23.0

23.5

24.0

24.5

25.0

25.5

26.0

-1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Level (0 = tote bottom)

Ab

so

rbe

d D

os

e (

kG

y)

Point Kernel Calculation and Alanine Measurement4 pass JS10000, 0.18 g/cc

19.5

20.5

21.5

22.5

23.5

24.5

25.5

26.5

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Level through Product Stack (0 = tote bottom)

Ab

so

rbed

Do

se (

kG

y)

Impact of Partial Pallet LoadsImpact of Partial Pallet LoadsImpact of Partial Pallet LoadsImpact of Partial Pallet Loads

Impact of Partial Product Load (0.4 g/cc)

0.90

1.00

1.10

1.20

1.30

1.40

1.50

1.60

1.70

1.80

1.90

2.00

2.10

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180

Product Height (cm)

Rela

tive D

ose D

istr

ibu

tio

n

Full Pallet 160-cm Product 140-cm 120-cm

Precision Dose Loop Precision Dose Loop Precision Dose Loop Precision Dose Loop Impact on Intervening ProductImpact on Intervening ProductImpact on Intervening ProductImpact on Intervening Product

Precision Dose LoopPrecision Dose LoopPrecision Dose LoopPrecision Dose Loop(Precision dose delivery for dose auditing, product (Precision dose delivery for dose auditing, product (Precision dose delivery for dose auditing, product (Precision dose delivery for dose auditing, product

testing, smalltesting, smalltesting, smalltesting, small----scale production)scale production)scale production)scale production)

• Assessment of dose distribution for the range of intervening product densities –predict impact on uniformity and cycle time1097.56542.510

1357911

50%

60%

70%

80%

90%

100%

110%

120%

130%

140%

150%

Transit Dose Profile (1 MCi, 0.19 g/cc)

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16

Absorbed Dose (kGy)

Le

ve

l a

bo

ve

Bo

tto

m T

ote

Assessment of ChangeAssessment of ChangeAssessment of ChangeAssessment of Change• Impact of change determined before

implementation – source re-configuration– slave pallet design changes – source shroud thickness change– support structure change

• Minimized risk to customer, even with significant change in irradiator and source geometry

Benchmarking ObjectivesBenchmarking ObjectivesBenchmarking ObjectivesBenchmarking Objectives

• Comparison of model predictions to independent measurements or calculations– Actual Production Irradiator (Canadian

Irradiation Centre, CIC) – A theoretical Gamma Irradiator– TT-100 Accelerator (Thurs. discussion/ Poster)

• Demonstration of the capabilities of selected point kernel and Monte Carlo codes

Canadian Irradiation CentreCanadian Irradiation CentreCanadian Irradiation CentreCanadian Irradiation Centre

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Dosimter Level (1 - 9 Bottom Compartment, 10-18 Top Compartment)

Ab

so

rbe

d D

os

e (

kG

y)

Carrier 2 Carrier 3 PK Test Front PK Test Mid

Cardboard Phantom at CIC

Alanine Measurements for Both Compartments

Preliminary Point Kernel Calculations (Bottom Compartment Only)

MCNP, PK Test (0.15 g/cc)

('Optimized' Source Distribution)

9.0

9.5

10.0

10.5

11.0

11.5

12.0

12.5

13.0

13.5

14.0

14.5

15.0

15.5

16.0

16.5

17.0

17.5

18.0

18.5

19.0

0 1 2 3 4 5 6 7 8Product Level

Ab

so

rbe

d D

os

e (

kG

y)

pk 8 Front Plane Axis 2 pk 8 Mid Plane Axis 2 mcnp 4 Front Plane Axis 2 mcnp 4 Mid Plane Axis 2

Determination of Density Determination of Density Determination of Density Determination of Density Distribution in Complex ProductDistribution in Complex ProductDistribution in Complex ProductDistribution in Complex Product

• Determination of Density Distribution in Complex Product

• Help to choose optimum treatment modality, and treatment parameters

• Applications in food treatment and next generation medical devices

Simulation: Whole chicken Simulation: Whole chicken Simulation: Whole chicken Simulation: Whole chicken (10 MeV e(10 MeV e(10 MeV e(10 MeV e----beam)beam)beam)beam)

• Simulation using TheraPlanTM Plus

• Density distribution determined via CT

• Two-sided treatment • Hot spots and cold

spots obvious (DUR not well defined, but at least 10 : 1)

Simulation: Whole chicken Simulation: Whole chicken Simulation: Whole chicken Simulation: Whole chicken (Gamma Technology, 2 side)(Gamma Technology, 2 side)(Gamma Technology, 2 side)(Gamma Technology, 2 side)

• Simulation usingTheraPlanTM Plus• Density distribution

determined via CT• 2-sided treatment • Excellent uniformity

~ 1.17

MCNP SetMCNP SetMCNP SetMCNP Set----up for Next Gen Device up for Next Gen Device up for Next Gen Device up for Next Gen Device Increasing Complexity of DeviceIncreasing Complexity of DeviceIncreasing Complexity of DeviceIncreasing Complexity of Device

(60(60(60(60----90 days!! to build MCNP input file for 50 90 days!! to build MCNP input file for 50 90 days!! to build MCNP input file for 50 90 days!! to build MCNP input file for 50 bodies)bodies)bodies)bodies)BioBioBioBio----absorbable materials more radioabsorbable materials more radioabsorbable materials more radioabsorbable materials more radio----sensitivesensitivesensitivesensitive

Low doses required, tighter uniformity, low T help protect Low doses required, tighter uniformity, low T help protect Low doses required, tighter uniformity, low T help protect Low doses required, tighter uniformity, low T help protect biologicbiologicbiologicbiologic

Patented Dose Delivery SystemPatented Dose Delivery SystemPatented Dose Delivery SystemPatented Dose Delivery System

Dose SculptingDose SculptingDose SculptingDose SculptingRadial Dose Distribution With/Without Aperture

30

50

70

90

110

130

150

170

190

210

230

250

270

290

-70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70

Distance from Central Axis (cm)

Ab

so

rbe

d D

os

e (

Gy

)

Precision Dose Concepts Precision Dose Concepts Precision Dose Concepts Precision Dose Concepts Next Gen Device and Full PalletNext Gen Device and Full PalletNext Gen Device and Full PalletNext Gen Device and Full Pallet

• Attenuators and rotation with modulation• Modified atmosphere, Temperature control

Dose Shaping Dose Shaping Dose Shaping Dose Shaping Next Gen Device and Full PalletNext Gen Device and Full PalletNext Gen Device and Full PalletNext Gen Device and Full Pallet

0.006.25

12.5018.75

25.00

0.00

6.25

12.50

18.75

25.00

1.00

1.05

1.10

1.15

1.20

1.25

1.30

1.35

1.30-1.35

1.25-1.30

1.20-1.25

1.15-1.20

1.10-1.15

1.05-1.10

1.00-1.05

15-cm aperture, constant rotation

Aperture and rotational speed modulation

SummarySummarySummarySummary

• Many examples of modelling with tangible benefits– Evaluation of cobalt source loadings. Impact of partial

product stacks. Effect of process interruption. Assessment of change. Reduction of OQ and PQ dosimetry.

• Many international organizations promote mathematical modelling– Participate in Thursday’s Workshops

• Barriers to entry for use exist, but many companies and institutions have succeeded