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  1. 1. Harald Paganetti (Geant4) Monte Carlo benchmarking(Geant4) Monte Carlo benchmarking
  2. 2. Why benchmarking ? 1. We are in Medical Physics ! 2. Monte Carlo is considered to be the gold standard 3. There are various competing codes/algorithms G4NAMU March2006 4. We want confidence in our code
  3. 3. 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 G4NAMU March2006
  4. 4. Types of Monte Carlo benchmarking A Benchmarking based on basic data • Comparison with experimental data • Comparison with theory Benchmarking done by developers (and users) G4NAMU March2006
  5. 5. Types of Monte Carlo benchmarking A Benchmarking based on basic data • Comparison with experimental data • Comparison with theory • MC intercomparison cross section data need to be accessible (MCNPX ?) G4NAMU March2006
  6. 6. 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 Benchmarking done by users only (!) We can all contribute (e.g., Poon, Paganetti) G4NAMU March2006
  7. 7. G4NAMU March2006
  8. 8. G4NAMU March2006
  9. 9. 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 G4NAMU March2006 Often not sufficient ! Often too user specific !
  10. 10. Types of Monte Carlo benchmarking A Benchmarking based on basic data • Comparison with experimental data • Comparison with theory • MC intercomparison 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) G4NAMU March2006
  11. 11. Cu Cu Cu….. ….. A B C Multi-Layer Faraday Cup (MLFC) p+ p+ charge 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)
  12. 12. 7.6 cm x 7.6 cm G4NAMU March2006
  13. 13. Multi-Layer Faraday Cup (MLFC) p+ Cu Cu Cu….. ….. charge 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)
  14. 14. G4NAMU March2006
  15. 15. Types of Monte Carlo benchmarking A Benchmarking based on basic data • Comparison with experimental data • Comparison with theory • MC intercomparison B Benchmarking based on standard ‘complex’ data • Comparison with experimental data • MC intercomparison We need standard benchmarking problems G4NAMU March2006
  16. 16. 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 G4NAMU March2006
  17. 17. Benchmarks Contribute a benchmark problem Submitted problems • Radiation Therapy Brachytherapy External Beam Therapy Proton Therapy • Imaging • Nuclear Medicine • Health Physics Too complex ! G4NAMU March2006
  18. 18. G4NAMU March2006 Submit only successful simulations to CMPWG and report unsuccessful ones to Geant4-developers !
  19. 19. Discussion: • We should compare cross section data used by various codes WHO ? • We need to design a set of (simple) benchmarking problems WHO ? G4NAMU March2006

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