harald paganetti (geant4) monte carlo benchmarking

Harald Paganetti

(Geant4) Monte Carlo benchmarking(Geant4) Monte Carlo benchmarking

Why benchmarking ?

1. We are in Medical Physics !2. Monte Carlo is considered to be the gold standard3. There are various competing codes/algorithms

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4. We want confidence in our code

Types of Monte Carlo benchmarking

A Benchmarking based on basic data• Comparison with experimental data• Comparison with theory• MC intercomparison

B Benchmarking based on ‘complex’ data• Comparison with experimental data• Comparison with theory• MC intercomparison

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A Benchmarking based on basic data• Comparison with experimental data• Comparison with theory

Benchmarking done bydevelopers (and users)

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cross section data need to be accessible (MCNPX ?)

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Benchmarking done by users only (!)

We can all contribute (e.g., Poon, Paganetti)

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Often notsufficient !

Often toouser specific !



B Benchmarking based on standard (‘complex’) data• Comparison with experimental data• Comparison with theory• MC intercomparison

Standard benchmarking problems should be simple (used by multiple users in various codes; easy error analysis)

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Cu Cu Cu….. …..

A B C

Multi-Layer Faraday Cup (MLFC)

p+

p+

char

ge

e.g., (p,pn) charge : 0 (+p; -recoil) 1 (+p)

p+

p+

n

80 %

Clean benchmark for nuclear models:

separated nuclear buildup region device has 100% acceptance for

charged secondaries technique measures charge, not

dose (no problems of dosimeter linearity and response to particle types)

7.6 cm x 7.6 cm

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Multi-Layer Faraday Cup (MLFC)

p+

Cu Cu Cu….. …..ch

arge

p+

p+

n

A B C

CH2 CH2CH2….. …..p+

p+

n

A B

e.g., (p,pn)charge : 0 (+p -recoil) 1 (+p)

can be used for high and low-Z !

e.g., (p,pn) charge : 0 (+p; -recoil) 1 (+p)

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B Benchmarking based on standard ‘complex’ data• Comparison with experimental data• MC intercomparison

We need standard benchmarking problems

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The Computational Medical Physics Working Group (CMPWG) is an international group dedicated to the pursuit of better computational tools in medical and health physics applications. CMPWG consists of individuals from the American Nuclear Society (ANS), American Association of Physicists in Medicine (AAPM), Society of Nuclear Medicine (SNM) , Health Physics Society (HPS) among others.CMPWG is hosted by two divisions within the American Nuclear Society.

• Mathematics and Computations Division (MCD) • Biology and Medicine

Upcoming Conferences • April 2006 - ANS RPSD 2006 - Carlsbad, New Mexico• June 2006 - ANS Annual Meeting - Reno, Nevada• July 2006 - AAPM 48th Annual Meeting - Orlando, Florida• October 2006 - First European Workshop on Monte Carlo Treatment Planning

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http://www.ans.org/

http://www.aapm.org/

Benchmarks

Contribute a benchmark problemSubmitted problems

• Radiation TherapyBrachytherapyExternal Beam TherapyProton Therapy

• Imaging• Nuclear Medicine• Health Physics

Too complex !

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CMPWG and report unsuccessful ones to Geant4-developers !

Discussion:

• We should compare cross section data used by various codes

WHO ?

• We need to design a set of (simple) benchmarking problems

WHO ?

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harald paganetti (geant4) monte carlo benchmarking

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