The Geant4 Hadrontherapy Advanced Example http://cern.ch/geant4 Developed by: G.A.P. Cirrone1, F. Di Rosa1, S. Guatelli2, M.G. Pia2, G. Russo1 1INFN Laboratori Nazionali del Sud, Italy 2INFN Genova, Italy

Contents User requirements Design of the physics component Implementation Geometry component Primary particle component Physics component Calculation of the energy deposit Analysis component How to execute the Hadrontherapy advanced example

User requirements

Results of the simulation User requirements The user shall be able to: Model a hadrontherapy beam line in terms of Geometry components Proton beam Model a phantom as a water box Model the electromagnetic and hadronic interactions Choose alternative approaches interactively to model Electromagnetic interactions Hadronic interactions Calculate the energy deposit in the phantom derived from: Both primary (the incident proton beam) and secondary particles Store the results of the simulation 3D energy deposit in the phantom Bragg peak Etc. in histograms and n-tuples Visualise the experimental set-up and the tracks of the particles Experimental set-up Physics Results of the simulation Visualisation

Design of the physics component Particles Messenger Alternative approaches to model p, n, pions hadronic interactions Modularised physics component The user can configure the simulation with different physics options transparently Alternative approaches to model protons, ions, e-, photons, e+ EM interactions

Implementation

Implementation Hadrontherapy example Classes header files in include/*.hh, source code in src/ *.cc main in Hadrontherapy.cc macro: defaultMacro.mac Classes HadrontherapyAnalysisManager HadrontherapyDetectorConstruction HadrontherapyDetectorMessenger HadrontherapyMaterial HadrontherapyPrimaryGeneratorAction HadrontherapyPhysicsList HadrontherapyPhysicsListMessenger ……

Detector Component The proton beam line is modelled in the experimental set-up in terms of: Geometrical components Materials Geant4 simulation

Primary particle component Mean value Sigma Energy 63.5 MeV 400. keV Position (x0, 0, 0) (0., 1., 1.) mm Direction (1., 0., 0.) (0., 0.0001, 0.0001) The primary particles are protons Origin of the primary particles X axis

Physics component Hadronic Electromagnetic Parameterized (à la GHEISHA) Nuclear Deexcitation Default evaporation GEM evaporation Fermi break-up Pre-equilibrium Precompound model Bertini model Intra-nuclear cascade Bertini cascade Binary cascade Elastic scattering Parameterized Bertini For protons and ions Standard Low Energy – ICRU 49 Low Energy – Ziegler 1977 Low Energy – Ziegler 1985 Low Energy – Ziegler 2000 For electrons and photons Low Energy – Livermore Low Energy – Penelope For positrons Low Energy - Penelope

Phantom The phantom is set in front the beam line Phantom: water box ( size: 40 mm ) Water box X axis The phantom is subdivided in 200 voxels along x, y, z axis The energy deposit is calculated in the voxels The result of the simulation is: 3D energy deposit in the phantom Energy deposit with respect to the depth in the phantom along the x axis

Analysis component AIDA 3.2.1 and PI 1.3.8 The simulation produces a .hbk file at the end hadrontherapy.hbk The Bragg peak is saved in a 1D histogram (ID = 10) The 3D energy deposit in the phantom is stored in a ntuple 3 109 events

Control, monitor the simulation

Messengers Interactive commands are defined to select: to change: Physics processes Physics models To model electromagnetic and hadronic interactions of particles to change: Geometrical parameters of the proton beam line Energy, position and direction of the primary particles

How to select the physics models Example of macro: /control/verbose 1 …….. /physics/addPhysics photon-epdl /physics/addPhysics electron-eedl /physics/addPhysics positron-standard /physics/addPhysics ion-LowE /physics/addPhysics muon-standard /physics/addPhysics decay /physics/addPhysics proton-precompound /run/initialize /run/beamOn 100

How to run Define necessary environment variables source … How to compile and link gmake How to run $G4WORKDIR/bin/Linux/Hadrontherapy (defaultmacro.mac is executed by default) Result of the simulation: hadrontherapy.hbk

Comments on the Geant4 physics Wide set of physics processes and models offered by Geant4 The Hadrontherapy advanced example provides examples of physics lists How to best choose the most appropriate model for a particular experimental set-up? The user has to select the physics models Electromagnetic and hadronic components The user has to validate his/her Geant4 physics component with respect to reference data A comprehensive assessment of Geant4 electromagnetic physics with respect to established reference data is documented in: K. Amako et al., Comparison of Geant4 electromagnetic physics models against the NIST reference data IEEE Trans. Nucl. Sci., Vol. 52, Issue 4, Aug. 2005, pp. 910-918