The Hadrontherapy Geant 4 advanced example P Cirrone

The Hadrontherapy Geant 4 advanced example P. Cirrone, G. Cuttone, F. Di Rosa, S. Guatelli, M. G. Pia, G. Russo 4 th Workshop on Geant 4 Bio-medical Developments, Geant 4 Physics Validation INF Genova, 13 -20 July 2005 Susanna Guatelli

Scope of the hadrontherapy Geant 4 application • Model a hadrontherapy beam line, – Donated by CATANA – Based on the CATANA beam line at INFN LNS Ligth field Laser • Calculate the energy deposit in a phantom • Dosimetry study Susanna Guatelli Modulator & Range shifter Monitor chambers Scattering system

Software process • The development of the hadrontherapy Geant 4 application follows an iterative-incremental approach • Software process products: – User Requirements document – Design – Documentation about the implementation is regularly updated Susanna Guatelli

The Hadrontherapy advanced example • Documentation of the example: www. ge. infn. it/geant 4/examples/index. html • Code review of the example in occasion of the last Geant 4 public release (7. 1) • Other changes: functionality added Susanna Guatelli

Design Primary particle Detector Physics List Susanna Guatelli Analysis

Simulation components • • • Primary particles Physics List Detector Construction Energy deposit Stepping action Analysis Susanna Guatelli

Primary particles • The primary particles are protons generated with initial energy, position and direction described by Gaussian distributions Particle type Position Direction Energy Proton Mean position (x = -3428. 59 mm, y = 0. ) Sigma position (0. , 1. mm) Mean direction (1. , 0. ) Sigma position (0. , 0. 0001) Mean energy 63. 45 Me. V Sigma energy 400 ke. V Susanna Guatelli • The primary particle component is provided of a messenger • It is possible to change these parameters interactively

Physics component The user can choose: • to activate EM physics only • to add on top the hadronic physics • to activate alternative models for both EM and hadronic physics Modularised physics component Particles: p, d, t, α, ions, e-, e+, pions, neutrons, muons Susanna Guatelli

EM Physics models • The user can choose to activate for protons the following alternative models: – – – Low Energy - ICRU 49, Low Energy - Ziegler 77, Low Energy - Ziegler 85, Low Energy Ziegler 2000, Standard • The user can choose for d, t, α, ions the alternative models: – Low Energy ICRU, – Standard • In the case of Low Energy Physics, also the nuclear stopping power is active Susanna Guatelli

EM Physics models • The user can choose to activate for e-: – Low. Energy EEDL, – Low. Energy Penelope, – Standard • The user can choose to activate for e+: – Low. Energy Penelope, – Standard • The user can choose to activate for gamma: – Low. Energy EPDL, – Low. Energy Penelope, – Standard Susanna Guatelli

Hadronic physics • Elastic scattering • Inelastic scattering – Alternative approaches for p, n, pions – LEP ( E < 100 Me. V) and Binary Ion model ( E > 80 Me. V) for d, t, α • Neutron fission and capture Susanna Guatelli

Hadronic physics list The user can select alternative hadronic physics lists for protons, pions and neutrons • Precompound model + default evaporation + GEM evaporation + default evaporation + Fermi Break-up + GEM evaporation + Fermi Break-up • Binary model + Precompound model ( with all the option showed above ) • Bertini model • LEP Susanna Guatelli

Detector Construction • Detailed description of the hadrontherapy beam line in terms of geometrical components and materials The user can change geometrical parameters of the beam line through interactive commands • The modulator is modeled • The user can rotate it between different runs Susanna Guatelli

Calculation of the energy deposit • The energy deposit is calculated inside a water phantom (size: 20 mm) set in front of the hadrontherapy beam line • The phantom is gridded in 80 x 80 voxels along x, y, z axis • The energy deposit of both primary and secondary particles is collected in the voxels Susanna Guatelli

Parameters • Threshold of production of secondary particles: 10 * mm • Cut per region fixed in the sensitive detector: 0. 001 mm for all the particles involved – More accurate calculation of the energy deposit • Max step fixed for all the particles in the sensitive detector = 0. 02 cm Susanna Guatelli

Result of the simulation • Energy deposit in the phantom • Bragg Peak along the axis parallel to the beam line (x axis) • Energy deposit of: – – – – secondary protons Electrons Gamma Neutrons Alpha He 3 Tritium Deuterium along the x axis Susanna Guatelli Proton beam x

Stepping action The user can retrieve useful information at the level of the stepping action: • The total number of hadronic interactions of primary protons in the phantom as respect to the electromagnetic ones • Which and how many secondary ions are produced in the phantom • The energy distribution of the secondary particles produced in the phantom is retrieved Susanna Guatelli

Analysis • Analysis tools: AIDA 3. 2 and PI 1. 3. 3 • The output of the simulation is a. hbk file with ntuples and histograms containing the results of the simulation: – Energy deposit in the phantom – Energy deposit of secondary particles in the phantom – Energy distributions of secondary particles originated in the phantom Susanna Guatelli

Future developments of the Geant 4 hadrontherapy advanced example • Design iteration – How to model more efficiently the geometry of the beam line • Code review Susanna Guatelli

Comments • The project of the hadrontherapy Geant 4 simulation is important for – Precise dosimetry for hadrontherapy – Geant 4 Physics validation • Comparison of the CATANA Bragg peak experimental measurements with simulation results – Validation of alternative Geant 4 e. m. and hadronic physics models – Talk on Monday Susanna Guatelli