Geant4 Accuracy and Benchmarking

Bruce Faddegon, UCSF

Geant4 e-/x-ray RT benchmarks

• SLAC– Makoto Asai– Tsukasa Aso– Joseph Perl– Jane Tinslay

Thick-target bremsstrahlung measurement at 10-30 MV

• Subtract pile-up spectrum and bkg• Add counts lost to pulse pile-up• Unfold detector response• Add counts lost to attenuation and

detector efficiency• Collimator effect

BA Faddegon, CK Ross, DWO Rogers, Medical Physics 17(5):773-785, 1990BA Faddegon, CK Ross, DWO Rogers, Medical Physics 18(4):727-739, 1991

No Bremsstrahlung SplittingGeant 4.7.1/EGSnrc

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0.5

1

1.5

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2.5

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3.5

4

Be Al Pb

Relative Simulation Time

Bremsstrahlung Splitting x 100Geant 4.8.0/EGSnrc

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10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

Be Al Pb

Relative Simulation Time