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M.Soukup 1 , M.Fippel 2 , F. Nuesslin 2 1 Department of Dosimetry and Application of Ionizing Radiation, Czech Technical University in Prague 2 Department for Medical Physics, University of Tuebingen. The importance of nuclear interactions for dose calculations in proton therapy.
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M.Soukup1, M.Fippel2, F. Nuesslin2 1 Department of Dosimetry and Application of Ionizing Radiation, Czech Technical University in Prague 2 Department for Medical Physics, University of Tuebingen The importance of nuclear interactions for dose calculations in proton therapy
Non negligible percentage of primary protons in proton therapy undergo nuclear interactions resulting in various secondary particles Monte Carlo most exact computing method development of fast Monte Carlo treatment planning system (VMCpro) radiobiological effect (RBE) Motivation
- Geant4 release 5.2 Open Source (http://www.cern.ch/geant4) Various models for inelastic hadronic interactions (Binary Cascade, Precompound model etc.) Various models for electromagnetic interactions (Standard, Low Energy Extension etc.) - Fluka2002.4 Freely available (http://www.fluka.org) but not Open Source Monte Carlo codes
Nuclear interactions with Geant4 versus experiment 10-9 pC/incident proton Channel Phantom and experimental results from H.Paganetti, B.Gottschalk, Medical physics Vol. 30, No.7, 2003
Depth dose distributions Fluka2002 Geant4 Geant4 – No nuclear interactions 100 MeV Dose per primary proton [MeV.cm2/g] 200 MeV Depth [cm]
Different materials (ICRU46) and energies e.g. 150MeV primary protons: Absorbed energy due to products of nuclear inelastic interactions Muscle adult 6.0% Skeleton adult 6.4% Soft tissue M 5.9% Water 5.8% (Binary Cascade, homogenous cylindrical phantom, z=20cm,r=8cm) Dose distributions – nuclear interactions
Products of inelastic nuclear processes – Contribution to depth dose distribution 150 MeV water Depth dose per primary proton [MeV.cm2/g] Depth [cm]
Absorbed energy due to inelastic nuclear interactions Precompound % of absorbed energy Energy of primary protons [MeV]
VMCpro versus Geant4, Fluka2002(no nuclear interactions) Depth dose distribution Absorbed dose Depth [mm] Geant4: 105 min., Fluka2002: 32 min. ,VMCpro: 2.5 min. !
European Commission – Marie Curie program Deutsche Forschungsgemeinschaft Acknowledgements: