PTRAN. McPTRAN.MEDIA, McPTRAN.CAVITY & McPTRAN.RZ. Hugo Palmans

Transcription

1 PTRAN McPTRAN.MEDIA, McPTRAN.CAVITY & McPTRAN.RZ Hugo Palmans Centre for Acoustics & Ionising Radiation, National Physical Laboratory, Teddington, Middlesex, UK

2 Louvain-la-Neuve 1994 Why PTRAN? D /D ion(eched) WaterCalorimeter NE2571 FWT-IC18 Exr-T2 Exr-T2

3 Incidental remark Why PTRAN here? Order out of chaos: McPTRAN.MEDIA McPTRAN.CAVITY (&McPTRAN.CHAMBER) McPTRAN.RZ Illustrative

4 PTRAN Martin Berger 1993 (NISTIR 5113) Available through NEA, RSICC Designed for calculation of dose distributions in water

5 PTRAN: pre-calculated grid T 0 δs 0 f V (λ) 0 T 1 δs 1 f V (λ) 1 T 2 δs 2 f V (λ) 2 f M (ϑ) 0 f M (ϑ) 1 f M (ϑ) 2 σ nuc0 σ nuc1 σ nuc2 E 0 s 0 x 0 y 0 z 0 θ 0 ϕ 0 E 1 s 1 x 1 y 1 z 1 θ 1 ϕ 1 W 1 E 2 s 2 x 2 y 2 z 2 θ 2 ϕ 2 W 2 T n δs n f V (λ) n f M (ϑ) n σ nucn E n s n x n y n z n θ n ϕ n W n

6 Vavilov PTRAN: energy straggling MeV E av = 0.25 MeV 0.15 f V (E) E ( MeV)

7 Molière PTRAN: multiple scattering MeV E av = 0.25 MeV f M (θ) θ (deg)

8 PTRAN: Total inelastic nuclear 600 interaction cross sections 500 σ (mbarn) E (MeV) Carlson et al, 1975 Renberg et al, 1972 PTRAN ICRU 63 Theoretical threshold (Selzer, 1993)

9 PTRAN: preparatory programs PARAM Parameters for Molière and Vavilov Path lengths in CSDA Nuclear attenuation coefficients VPREP: Vavilov distribution MPREP: Molière distribution

10 PTRAN: transport algorithm (x 0,y 0,z 0 ) = (0,0,0); (u 0,v 0,w 0 ) = (0,0,1) E 0 is only parameter E n E n-1 from Vavilov at nearest T i s n by interpolation θ from Molière at [T i,t i+1 ] & ϕ uniform between -180 and +180 degrees. (θ,ϕ ) transformed to (θ,ϕ) using [R] x, y, z calculated x, y, z transformed to x, y, z using [R] Stop when E n < E cut or E n < E fin and dump E n

11 PTRAN: random generator Default = congruential generator, period 2 28 Optional: Lagged Fibonacci (Marsaglia- Zaman, 1987) period 2 144

12 PTRAN: scoring geometry transport scoring z 1 /r 0 z i /r 0

13 PTRAN: scoring (de/dz) C, estimated as (S/ρ) cross W cross /cosθ cross (de/dz) N, estimated as E cross µ cross W cross /cosθ cross Φ estimated as 1/cosθ cross Spectral distribution of Φ and radial distribution of (de/dz) C

14 Input file Boundary file

15 Example: 60 MeV pdd de/dx MeV g -1 cm PTRAN Geant4 - QGSP_BIC MCNPX 60 MeV protons in water depth (mm)

16 Example: 250 MeV pdd de/dx MeV g -1 cm MeV protons in water PTRAN Geant4 - QGSP_BIC depth (mm)

17 Examples: proton spectra fluence 1E+00 1E-01 1E-02 (s w,air )=+0.03% (s w,air )=-0.04% Spectra at 0.9 x r 0 PTRAN-050MeV PTRAN-150MeV PTRAN-250MeV MCNPX-050MeV MCNPX-150MeV MCNPX-250MeV 1E-03 (s w,air )=-0.15% 1E E (MeV)

18 Example: radial distributions (150 MeV) 2.0 (de/dz)c (MeV cm 2 g -1 ) z /r 0 = 0.90 z /r 0 = 0.50 z /r 0 = r (mm)

19 McPTRAN.MEDIA: aim Other materials than water Inhomogeneous slab geometries Broad rectangular and circular beams Incident beam with energy distribution Incident beam with angular distribution Implementation of modulator wheel

20 McPTRAN.MEDIA: data Stopping powers: ICRU 49 (for materials not listed: Bragg + I 0 + Barkas) For Vavilov: S 1 and I 1 (from Inokuti et al. 1978, 1981 Phys. Rev. A 17: and 23:95-109) For Molière: k HF (from Berger and Wang 1988 ed. Jenkins ) Inelastic nuclear cross sections: Janni (1982) and ICRU 63 (for materials not listed: interpolation as a function of A)

21 s alanine,water McPTRAN.MEDIA: Stopping powers (consistent with ICRU 49) Bragg ICRU49 recommend. Bragg alanine alanine pellet (NPL) s alanine,pmma Bragg Bragg alanine ICRU49 recommend. alanine pellet (NPL) 0.98 ICRU49 recommend ICRU49 recommend Energy (MeV) Energy (MeV)

22 McPTRAN.MEDIA: Total inelastic nuclear cross sections Janni ICRU63 σ inel /A (mbarn) water graphite polystyrene A150 PMMA air E (MeV) E (MeV) aluminium

23 McPTRAN.MEDIA: geometry transport scoring z 1 z i (expressed in cm)

24 McPTRAN.MEDIA: boundary crossing Linear interpolation of Energy loss Angle Displacements x, y, z

25 McPTRAN.MEDIA: example: fluence correction factors D ( z ) = D ( z ). s pl.φ w w pl pl w, pl w z w = z pl. () z 0 w () z0 pl

26 McPTRAN.MEDIA: example: fluence correction factors 6% Janni ICRU 63 3% 4% 2% φ w PMMA -1 2% 0% 50 MeV -2% 100 MeV 150 MeV -4% 200 MeV 250 MeV -6% z/z 0 1% 0% -1% -2% -3% z/z 0

27 McPTRAN.MEDIA: example: fluence correction factors sw,pmma (σ n/a)w,pmma ICRU 63 Janni (1982) E (MeV) E (MeV)

28 McPTRAN.MEDIA: example: fluence correction factors correct conversion 6% Janni ICRU 63 3% φ w PMMA -1 4% 2% 2% 1% 0% z/z 0 0% z/z 0

29 6% McPTRAN.MEDIA: example: fluence correction factors 3% φ w PMMA -1 4% 2% 2% 1% 0% z 0 -z res (mm) 0% z 0 -z res (mm) D w ( z w ) = D pl ( z pl ) [( ρ) + ( σ )] S E A wpl, e N A T0 T S w 1 σ ( T ') A w S pl 1 σ ( T ') A pl dt '

30 McPTRAN.MEDIA versus McNP and Geant: fluence correction factors PTRAN GEANT4 MCNPX fluence correction factor (a) (b) (c) water equivalent depth (cm)

31 McPTRAN.MEDIA: example: bone slab in water de/dz (Mev cm 2 g -1 ) D bone /D water D (water/bone) /D water depth (mm water)

32 McPTRAN.MEDIA: modulator wheel transport sampled from dϕ /de E relative contribution cumulative distribution z thickness (mm) 0.0 z i d wheel

33 Interlude: Modulator wheel in GEANT4 (Paganetti 2004 Phys. Med. Biol. 49:N75-N82)

34 McPTRAN.MEDIA + modwheel: example: spectra in modulated proton beam 1E+00 dϕ/de (MeV -1 ) 1E-01 1E-02 z/r 0 = 1.0 z/r 0 = 0.9 z/r 0 = 0.6 z/r 0 = 0.3 1E E (MeV)

35 McPTRAN.MEDIA: example: stopping power ratios in modulated proton beam 0.0 % difference with mono-e % x E eff Palmans and Verhaegen (1998) Medin and Andreo (1992) E eff (MeV)

36 McPTRAN.CAVITY: geometry & scoring dϕ /de E geometry interrogation region z 1 z i d wheel

37 McPTRAN.CAVITY: example: p wall,gr relative dose McPTRAN.CAVITY Experiment thickness wall + build-up cap (mm)

38 McPTRAN.CAVITY: example: gradient corrections for thimble IC (see grid calculation demo) Dair (MeV g -1 ) per proton per cm MeV depth (mm)

39 McPTRAN.CAVITY: example: secondary electron perturbation (Verhaegen and Palmans, Med. Phys. 28: ) Dw,NE2571/Dw,Chamber C/C PTW Wellhöfer-IC70 A-150/Al NE2581 PTW PTW Wellhöfer-IC69 Nylon 66/Al FTW-IC18 Exradin-T2 Chamber

40 McPTRAN.RZ dϕ /de E z 1 z i (expressed in cm)

41 McPTRAN.RZ: example: Alanine stack in PMMA

42 McPTRAN.RZ: example: Alanine stack in PMMA D (MeV g -1 ) depth (cm)

43 That s all folks Thanks!