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Harald Paganetti

(Geant4) Monte Carlo benchmarking. Harald Paganetti. 4. We want confidence in our code. Why benchmarking ?. We are in Medical Physics ! Monte Carlo is considered to be the gold standard There are various competing codes/algorithms. G4NAMU March 2006. Types of Monte Carlo benchmarking.

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Harald Paganetti

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  1. (Geant4) Monte Carlo benchmarking Harald Paganetti

  2. 4. We want confidence in our code Why benchmarking ? • We are in Medical Physics ! • Monte Carlo is considered to be the gold standard • There are various competing codes/algorithms G4NAMU March 2006

  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 March 2006

  4. Types of Monte Carlo benchmarking • A Benchmarking based on basic data • Comparison with experimental data • Comparison with theory G4NAMU March 2006 Benchmarking done by developers (and users)

  5. cross section data need to be accessible (MCNPX ?) Types of Monte Carlo benchmarking • A Benchmarking based on basic data • Comparison with experimental data • Comparison with theory • MC intercomparison G4NAMU March 2006

  6. We can all contribute (e.g., Poon, Paganetti) 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 March 2006 Benchmarking done by users only (!)

  7. G4NAMU March 2006

  8. G4NAMU March 2006

  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 Often not sufficient ! Often too user specific ! G4NAMU March 2006

  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 G4NAMU March 2006 Standard benchmarking problems should be simple (used by multiple users in various codes; easy error analysis)

  11. A B C Cu Cu Cu ….. ….. Multi-Layer Faraday Cup (MLFC)  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) p+ charge p+ p+ p+ n e.g., (p,pn) charge : 0 (+p; -recoil) 1 (+p)

  12. G4NAMU March 2006 7.6 cm x 7.6 cm

  13. A B CH2 CH2 CH2 p+ ….. ….. p+ n e.g., (p,pn) charge : 0 (+p -recoil) 1 (+p) Multi-Layer Faraday Cup (MLFC) can be used for high and low-Z ! p+ charge A B C Cu Cu Cu p+ ….. ….. p+ n e.g., (p,pn) charge : 0 (+p; -recoil) 1 (+p)

  14. G4NAMU March 2006

  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 G4NAMU March 2006 We need standard benchmarking problems

  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 G4NAMU March 2006 • 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

  17. Too complex ! Benchmarks • Contribute a benchmark problem • Submitted problems • Radiation Therapy Brachytherapy External Beam TherapyProton Therapy • Imaging • Nuclear Medicine • Health Physics G4NAMU March 2006

  18. Submit only successful simulations to CMPWG and report unsuccessful ones to Geant4-developers ! G4NAMU March 2006

  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 March 2006

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