PTRAN McPTRAN.MEDIA, McPTRAN.CAVITY & McPTRAN.RZ Hugo Palmans Centre for Acoustics & Ionising Radiation, National Physical Laboratory, Teddington, Middlesex, UK
Louvain-la-Neuve 1994 Why PTRAN? 1.07 1.06 D /D ion(eched) WaterCalorimeter 1.05 1.04 1.03 1.02 1.01 1.00 NE2571 FWT-IC18 Exr-T2 Exr-T2
Incidental remark Why PTRAN here? Order out of chaos: McPTRAN.MEDIA McPTRAN.CAVITY (&McPTRAN.CHAMBER) McPTRAN.RZ Illustrative
PTRAN Martin Berger 1993 (NISTIR 5113) Available through NEA, RSICC Designed for calculation of dose distributions in water
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
Vavilov PTRAN: energy straggling 0.25 0.20 60 MeV E av = 0.25 MeV 0.15 f V (E) 0.10 0.05 0.00 0.10 0.20 0.30 0.40 0.50 E ( MeV)
Molière PTRAN: multiple scattering 0.040 60 MeV E av = 0.25 MeV 0.030 f M (θ) 0.020 0.010 0.000 0.0 0.2 0.4 0.6 θ (deg)
PTRAN: Total inelastic nuclear 600 interaction cross sections 500 σ (mbarn) 400 300 200 100 0 1 10 100 1000 E (MeV) Carlson et al, 1975 Renberg et al, 1972 PTRAN ICRU 63 Theoretical threshold (Selzer, 1993)
PTRAN: preparatory programs PARAM Parameters for Molière and Vavilov Path lengths in CSDA Nuclear attenuation coefficients VPREP: Vavilov distribution MPREP: Molière distribution
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
PTRAN: random generator Default = congruential generator, period 2 28 Optional: Lagged Fibonacci (Marsaglia- Zaman, 1987) period 2 144
PTRAN: scoring geometry transport scoring z 1 /r 0 z i /r 0
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
Input file Boundary file
Example: 60 MeV pdd de/dx MeV g -1 cm 2 80.0 70.0 60.0 50.0 40.0 30.0 20.0 10.0 PTRAN Geant4 - QGSP_BIC MCNPX 60 MeV protons in water 0.0 27.0 0.0 5.0 28.0 10.0 29.0 15.030.0 20.0 31.025.0 32.0 30.0 33.0 35.0 depth (mm)
Example: 250 MeV pdd de/dx MeV g -1 cm 2 20.0 18.0 16.0 14.0 12.0 10.0 8.0 6.0 4.0 2.0 0.0 250 MeV protons in water PTRAN Geant4 - QGSP_BIC 0 100 200 300 400 depth (mm)
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-04 10.0 100.0 1000.0 E (MeV)
Example: radial distributions (150 MeV) 2.0 (de/dz)c (MeV cm 2 g -1 ) 1.5 1.0 0.5 z /r 0 = 0.90 z /r 0 = 0.50 z /r 0 = 0.99 0.0 0.0 5.0 10.0 15.0 r (mm)
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
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 17:1229-1231 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)
s alanine,water McPTRAN.MEDIA: Stopping powers (consistent with ICRU 49) 1.01 1.00 0.99 Bragg ICRU49 recommend. Bragg alanine alanine pellet (NPL) s alanine,pmma 1.03 1.02 1.01 Bragg Bragg alanine ICRU49 recommend. alanine pellet (NPL) 0.98 ICRU49 recommend. 1.00 ICRU49 recommend. 0.97 0.99 1 10 100 1000 Energy (MeV) 1 10 100 1000 Energy (MeV)
McPTRAN.MEDIA: Total inelastic nuclear cross sections Janni ICRU63 σ inel /A (mbarn) 40.0 30.0 20.0 10.0 water graphite polystyrene A150 PMMA air 0.0 1 10 100 1000 E (MeV) 1 10 100 1000 E (MeV) aluminium
McPTRAN.MEDIA: geometry transport scoring z 1 z i (expressed in cm)
McPTRAN.MEDIA: boundary crossing Linear interpolation of Energy loss Angle Displacements x, y, z
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
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% 0 0.2 0.4 0.6 0.8 1 z/z 0 1% 0% -1% -2% -3% 0.0 0.2 0.4 0.6 0.8 1.0 z/z 0
McPTRAN.MEDIA: example: fluence correction factors 1.04 1.00 1.03 0.95 sw,pmma 1.02 1.01 (σ n/a)w,pmma 0.90 0.85 0.80 0.75 ICRU 63 Janni (1982) 1.00 1 10 100 1000 E (MeV) 0.70 0 50 100 150 200 E (MeV)
McPTRAN.MEDIA: example: fluence correction factors correct conversion 6% Janni ICRU 63 3% φ w PMMA -1 4% 2% 2% 1% 0% 0.0 0.2 0.4 0.6 0.8 1.0 z/z 0 0% 0.0 0.2 0.4 0.6 0.8 1.0 z/z 0
6% McPTRAN.MEDIA: example: fluence correction factors 3% φ w PMMA -1 4% 2% 2% 1% 0% 0.0 100 200 300 400 z 0 -z res (mm) 0% 0.0 100 200 300 400 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 '
McPTRAN.MEDIA versus McNP and Geant: fluence correction factors PTRAN GEANT4 MCNPX fluence correction factor 1.030 1.020 1.010 1.000 (a) (b) (c) 0.990 0.980 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 0.5 1.0 1.5 2.0 2.5 3.0 3.5 water equivalent depth (cm) 0.5 1.0 1.5 2.0 2.5 3.0 3.5
McPTRAN.MEDIA: example: bone slab in water 1.02 1.010 de/dz (Mev cm 2 g -1 ) 1.00 0.98 0.96 0.94 0.92 0.90 D bone /D water D (water/bone) /D water 0 50 100 150 200 250 300 depth (mm water) 1.005 1.000 0.995 0.990
McPTRAN.MEDIA: modulator wheel transport sampled from 0.15 1.0 dϕ /de E relative contribution 0.10 0.05 0.8 0.6 0.4 0.2 cumulative distribution z 1 0.00 0 10 20 30 40 thickness (mm) 0.0 z i d wheel
Interlude: Modulator wheel in GEANT4 (Paganetti 2004 Phys. Med. Biol. 49:N75-N82)
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-03 0 20 40 60 80 100 E (MeV)
McPTRAN.MEDIA: example: stopping power ratios in modulated proton beam 0.0 % difference with mono-e -0.2-0.4-0.6-0.8-1.0-4.8% x E eff -0.71 Palmans and Verhaegen (1998) Medin and Andreo (1992) 0 50 100 150 200 250 E eff (MeV)
McPTRAN.CAVITY: geometry & scoring dϕ /de E geometry interrogation region z 1 z i d wheel
McPTRAN.CAVITY: example: p wall,gr 1.050 1.040 relative dose 1.030 1.020 1.010 McPTRAN.CAVITY Experiment 1.000 0.990 0.0 2.0 4.0 6.0 8.0 10.0 thickness wall + build-up cap (mm)
McPTRAN.CAVITY: example: gradient corrections for thimble IC (see grid calculation demo) Dair (MeV g -1 ) per proton per cm 2 70.0 60.0 50.0 40.0 30.0 20.0 10.0 60 MeV 0.0 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 depth (mm)
McPTRAN.CAVITY: example: secondary electron perturbation (Verhaegen and Palmans, Med. Phys. 28:2088-2095) 1.020 1.015 1.010 1.005 Dw,NE2571/Dw,Chamber 1.000 0.995 C/C PTW-30002 Wellhöfer-IC70 A-150/Al NE2581 PTW-30001 PTW-30006 Wellhöfer-IC69 Nylon 66/Al FTW-IC18 Exradin-T2 Chamber
McPTRAN.RZ dϕ /de E z 1 z i (expressed in cm)
McPTRAN.RZ: example: Alanine stack in PMMA
McPTRAN.RZ: example: Alanine stack in PMMA 10.0 8.0 D (MeV g -1 ) 6.0 4.0 2.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 depth (cm)
That s all folks Thanks!