1. (Geant4) Monte Carlo benchmarking
Harald Paganetti

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

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
March 2006
G4NAMU

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

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

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
March 2006
G4NAMU
We can all contribute (e.g., Poon, Paganetti)
Benchmarking done by users only (!)

7. March 2006
G4NAMU

8. March 2006
G4NAMU

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

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

11. 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 Cu
….. A B C p+ p+ p+ n
e.g., (p,pn) charge : (+p; -recoil) 1 (+p)

12. March 2006
G4NAMU
7.6 cm x 7.6 cm

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

14. March 2006
G4NAMU

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
March 2006
G4NAMU
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
March 2006
G4NAMU
Upcoming Conferences
April ANS RPSD Carlsbad, New Mexico
June ANS Annual Meeting - Reno, Nevada
July AAPM 48th Annual Meeting - Orlando, Florida
October First European Workshop on Monte Carlo Treatment Planning

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

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

19. We should compare cross section data used by various codes WHO ?
Discussion:
We should compare cross section data used by various codes
WHO ?
We need to design a set of (simple) benchmarking problems
March 2006
G4NAMU