From Russia with Love Monte Carlo Particle Transport Code SHIELD-HIT(10A)

Transcription

1 From Russia with Love Monte Carlo Particle Transport Code (10A), PhD, Department of Physics and Astronomy Aarhus University, Denmark Department of Experimental Clinical Oncology Aarhus University Hospital, Denmark David C. Hansen, Armin Lühr, Nikolai Sobolevsky

2 MC Treatment Planning Publications

3 Common MC Codes Photons & Electrons only EGS4, EGSnrc, BEAMnrc (National Research Council of Canada) Penelope (Facultat de Fisica (ECM), Universitat de Barcelona) MCNP (including neutrons) Photons & Electrons + Ions FLUKA (CERN) Geant4 (CERN) PHITS (Japan Atomic Energy Agency) MCNPX (Los Alamos National Laboratory) Ions only: SHIELD(-HIT) (Institute for Nuclear Research RAS)

4 Common MC Codes in Use Number of publications ISI Web of Knowledge Year

5 Common MC Codes in Use

6 Compare MC codes with cars: Monte Carlo Programs in Particle Therapy Research A FLUKA car A Geant4 car A car

7 History of SHIELD - Overview SHIELD developed at JINR RSICC No.CCC-667 Transport of nucleons and pions up to 30 GeV Continued at Institute for Nuclear Research of the Russian Academy of Sciences (INR) Rewritten , Transport of nucleons, antinucleons, pions and kaons up to 1 TeV Fortran 77 SHIELD-HI 1997: Transport of ions with arbitrary A and Z 2001: Heavy Ion Therapy (INR, DKFZ, Karolinska)

8 SHIELD-HI - Features Transport of (anti-)nucleons, pions, kaons, and arbitrary nuclei in energy range up to 1 TeV/A. Geometric configuration of the target using combinatorial geometry (CG) Arbitrary chemical and isotopic composition of materials in target zones. Two- and three-particle modes of decay of pions and kaons. Simulation of the inelastic hadron-nucleus and nucleusnucleus interaction in exclusive approach (MSDMgenerator).

9 SHIELD-HI - Features Memorizing of the extra-nuclear cascade tree during simulation without any loss of physics information Neutron generation (En < 14.5 MeV), electrons/positrons (and g-quanta ) during the simulation of extra-nuclear cascades. Neutron transport (LOENT, MCNP possible) Modular architecture of code Total and inelastic cross sections of the hadron-nucleus and nucleus-nucleus interaction follow data from Dubna (several publications by Barashenko and Sychev)

10 SHIELD(-HI) - Features Scoring in each geometric zone of the target: Energy Production rate of radioisotopes Track Length Estimation (TLE) of differential total fluences and of secondary particles and nuclear fragments

11 Multi Stage Dynamical Model - MSDM MSDM describes all stages of inelastic nuclear interactions (exclusive approach) Current versions of known Russian nuclear models are interfaced: Fast, cascade stage of the nuclear reaction Intranuclear cascade model DCM (Dubna Cascade Model) (Toneev et al.) Independent quark-gluon string model (QGSM) (Amelin et al.) Coalescence model (Toneev et al) Precompound emission of nucleons and lightest nuclei (Gudima et al). Equilibrium deexcitation of residual nucleus Fermi break-up of light nuclei (Botvina et al) Evaporation/Fission competition (Botvina et al and Adeev et al) Multifragmentation of highly excited nuclei (SMM) (Botvina et al)

12 Neutron Transport Neutron transport below 14.5 MeV in the SHIELD code is simulated by LOENT (Low Energy Neutron Transport) using the 28 group neutron data system ABBN (In Russian by, Abagayan et al.) The LOENT code may be used both separately and as a part of the SHIELD code. SHIELD and LOENT have common geometric module (CG) as well as several common subroutines.

13 Neutron Transport (cont.) The LOENT code uses the following information from the ABBN neutron data system: st - total cross section; sf - fission cross section (n,f); n - mean number of fission neutrons; sc - capture cross section (n,c); sin - inelastic scattering cross section (n,n ), including the reaction (n,2n); se - elastic scattering cross section (n,n); m - mean cosine of the angle of the elastic scattering; sin(g,g+k) - matrix of inter group transitions at the inelastic scattering.

14 Neutron Transport (cont.) LOENT gets neutrons from an external source and follows them, one by one, until the end of the neutron trajectory. The multiplication of neutrons in the reactions (n,2n) and (n,f) is possible. Each neutron has its statistical weight attached as well as the cumulative timer, which accumulates the time from the beginning of the neutron history. After transition of the neutron to the thermal group, its energy does not change in further collisions.

15 (Heavy Ion Therapy) was designed for precise simulation of interaction of therapeutic beams of protons and ions with biological tissue

16 v1 (2001) Implementation of the Gaussian and Vavilov s models of fluctuations of the ionization energy loss (i.e.: energy straggling) Gaussian model of multiple Coulomb scattering (Fermi distribution) Track Length Estimation (TLE) of the differential energy fluence and double differential fluence of secondary particles and nuclear fragments in each geometric zone of the target.

17 v1 (2001)

18 v1 (2001) (cont.) Scoring of contributions to the energy deposition from various types and from different generations of particles and nuclear fragments separately. External stopping power tables can be read. Protons and α-particles : ICRU 49. The possibility to switch on/off various physics processes (energy straggling, multiple scattering, nuclear interactions) by user request.

19 v2 (2005) Stopping power Implementation of Li up to Ar in the tabular form according to ICRU 73 External tables can be loaded Modification of the Bethe-Bloch equation for stopping powers and smooth sewing of it with the Lindhard-Scharff equation at low energies.

20 v2 (2005) (cont.)

21 v2 (2005) (cont.)

22 v2 (2005) (cont.) All transport now double precision. Refinement of energy grids in the transport part of. Reduction of the energy cutoff for a transport down to Ecut = 25 kev/u. Improvement the total and inelastic cross section of ha and AA interaction function. Improvement of the Fermi break-up model.

23 07 Moliere scattering model added (another flavour of coulomb scattering)

24 07 (cont.) Variable dimensioning of the energy grid for scoring TLE fluence Improvement of the TLE algorithm in the vicinity of the Bragg peak Calculation of the absorbed dose by TLE fluences and stopping powers for any particle in each geometric zone of the target. Decomposition of the absorbed dose within user defined Linear Energy Transfer (LET) intervals

25 07 (cont.) Increasing the max. number of chemical elements from 8 up to 13 (better tissue handling) Revision of the 28-group neutron data (En < 14.5 MeV) for several chemical elements (F, P, S, Cl, Ti, Zn, Au) which are relevant to hadron therapy

26 10A Usability External Spread Out Bragg Peak files (from TRiP) Ripple Filter Arbitrary scoring grids (cartesian, cylindrical) Scoring of particle energy - spectra files in TRiP format (TIFF like) and plenty of new estimators User's manual (in English!) Interface to SimpleGEO for CG visualization Computation speed Parallelization New random number generator Nuclear models Fine tuning of inelastic cross sections following new experimental data from GSI (Darmstadt)

27 10A Ripple Filter

28 10A Random Number Generator Earlier RANLUX was used RANLUX was identified as CPU bound bottleneck Plenty of different random number generators exist MCRNG, LCRNG, RANLUX, RANCHI RANLUX was replaced with RANCHI Hardness testing (e.g. DIEHARD) Problems when parallelizing was taken care of

29 10A - Scoring

30 10A - Scoring

31 10A - Scoring

32 Input files

33 INPUT FILES for022.dat chemical composition of materials in target zones for023.dat several parameters (like seed, projectile, statistics etc.) pasin.dat geometry of the target. CG geometry is used (similar to FLUKA). Optionally, the user can include detect.dat for simple scoring of geometries. Static files: atab.dat quark composition of particles tabnuc.dat natural isotope composition of chemical elements

34 Formatted F77 style input...

35 Specify Geometry A particle needs to know where it is A particle needs to know where it is going Geometry constructed from primitives using boolean logic A B C D

36 Combinational Geometry (CG) The geometry is described using the combinational geometry (GC) module known from the neutron transport program MORSE Own implementation hereof in SHIELD: GEMCA

37 Geometric Primitives

38 CG Boolean Logic

39 Combinatorial Geometry

40 FLUKA input file

41 Additional Parameters

42 BENCHMARKS

43 10A - Benchmark

44 10A - Benchmark

45 10A - Benchmark

46 10A - Benchmark

47 TODO

48 What can't do (TODO) Electron/positron/photon transport Free scoring does not work for fluence in vacuum Voxel based targets (CT scans), needs rewrite of GEMCA User selection of beam angles and isotropic fields Binary output for averaging multiple runs Monolithic input file, with include option. Fix Licensing

49 How to get it / Licensing Currently code is only available upon request from INR in terms of collaboration agreement 10A Copyright by INR and Aarhus University. All other versions are exclusively INR. Several models were discussed (proprietary, dual license, GPL etc...) Future licensing will most likely be Free binary version for public research institutes Source available upon a signed MOU Commercial version available against cash Currently GPL code is in, therefore not released yet.

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