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Results from the recent carbon test beam at HIMAC

Results from the recent carbon test beam at HIMAC. Koichi Murakami Statoru Kameoka KEK CRC. supported by. Introduction. A joint project among Geant4 developers, astro-physicists and medical physicists in Japan Development of software framework for simulation in radiotherapy

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Results from the recent carbon test beam at HIMAC

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  1. Results from the recent carbon test beam at HIMAC Koichi Murakami Statoru Kameoka KEK CRC supported by Geant4 Physics Verification and Validation (17-19/Jul./2006)

  2. Introduction • A joint project among Geant4 developers, astro-physicists and medical physicists in Japan • Development of software framework for simulation in radiotherapy • funded by the Core Research for Evolutional Science and Technology (CREST) program organized by Japan Science and Technology Agency (JST) from 2003 to 2008 • The project goal • provides a set of software components for simulation in radiotherapy (especially hadrontherapy), • well designed general purpose software framework • DICOM/DICOM-RT interface • application of GRID computing technology • visualization tools • In addition, physics validation is one of key issues. Geant4 Physics Verification and Validation (17-19/Jul./2006)

  3. Physics Validation in Radiotherapy • Geant4 has to reproduce precise dose distributions in human body. • which requires correct simulation for the interactions between various types of beams (X-ray, proton, heavy ions) and materials along beam line • reliable descriptions of • electromagnetic processes • hadronic/nuclear processes • nuclear decay processes in the relevant energy regions and particle types. • These are non-trivial issues! • Physics validation is one of the most critical aspects in the project. Geant4 Physics Verification and Validation (17-19/Jul./2006)

  4. Hadrontherapy Facilities in Japan Jpn(world) # Proton beam facilities: 5 (23) # Ion beam facilities: 2 (4) The Energy Research Center Wakasa Bay (Tsuruga: 200 MeV) U. of Tsukuba PMRC (Tsukuba: 250 MeV) Hyogo Ion Beam Medical Center (Nishi-Harima: 320 MeV/u) NCC East Hospital (Kashiwa: 235 MeV) NIRS (Chiba: 90 MeV, 400MeV/u) Shizuoka Cancer Center (Mishima: 230 MeV) Proton beam Ion beam Geant4 Physics Verification and Validation (17-19/Jul./2006)

  5. Experiment Areas Ion Source RFQ Linac 800 KeV/u Alvarez Linac 6 MeV/u Synchrotron 800 MeV/u Treatment Rooms ~65 m HIMAC at NIRS • Operation since 1994 • Treatment beam: 12C • Over 2,000 patients have been treated Geant4 Physics Verification and Validation (17-19/Jul./2006)

  6. Ref. http://www.nirs.go.jp/tiryo/himac/himac2.htm 100 Ｘ-ray g-ray 50 Relative Dose (%) neutron proton carbon 0.0 10.0 15.0 5.0 Depth - Human Body (cm) Hadron (proton/carbon) Beam • A sharp peak of energy deposition at the end of the range (Bragg peak) • The sharp fall-off of the Bragg peak for carbon beam • A small range straggling • Carbon produces a longer tail after the Bragg peak. Hadron beams allow conformation of dose distribution better than photons and electrons; Geant4 Physics Verification and Validation (17-19/Jul./2006)

  7. Conformation of Irradiation Field Patient body Collimator Wobbler magnets Ridge Filter Range Shifter Target volume (tumor) X Y Scatterer Beam Compensator (Bolus) By = Ay sin(wt) Bx = Ax sin(wt+p/2) Ridge Filter Spiral beam divergence to create a uniform irradiation field Bragg peak dose Spread-out Bragg peak (SOBP) Depth Geant4 Physics Verification and Validation (17-19/Jul./2006)

  8. Experimental Setup Beam Energy290, 400 MeV/u Multi-leaf Collimator (open) Acrylic vessel Vacuum window Range shifter (unused) Dose Monitor (ionization Chamber) Water target Collimator Wobber magnets Collimator Scatterer (lead) X Y Beam 12C Beam profile Monitor (ionization Chamber) Ridge filter (aluminum) Treatment position (isocenter) Secondary emission monitor Test beam line of HIMAC(NIRS) Geant4 Physics Verification and Validation (17-19/Jul./2006)

  9. Water target 2 mm Scored region 1 mm 2 mm 400 mm Beam (12C) Water target / Scored region • Dose distribution in a water target was measured using the horizontal arrayed dosimeters • voxel size of each element is 2 x 2 x 1 mm. • scanning along the depth direction Geant4 Physics Verification and Validation (17-19/Jul./2006)

  10. Physics List • Generic Ions • elastic scattering • Binary light ion cascade or JQMD • cross section : Tripathi / Shen • radioactive decay • ionization / multiple scattering • Hadron • elastic scattering • L(H)EP+Binary cascade • ionization / multiple scattering • electron/gamma • standard EM Geant4 Physics Verification and Validation (17-19/Jul./2006)

  11. Bragg Peak Simulation(Binary Cascade) 290MeV/u • Overall profile of Bragg peak seems to be well reproduced, but… • We found a small bump just before the peak… What is this!? 40oMeV/u Geant4 Physics Verification and Validation (17-19/Jul./2006)

  12. Bragg Peak – more in detail BC JQMD • Secondaries of 11C produce the bump of BC. • JQMD shows no bump. • Production rates of 11C (one neutron stripped off) and 11B (one proton stripped off) are different between Binary Cascade and JQMD. • Production rate of 11C in BC is over created. Geant4 Physics Verification and Validation (17-19/Jul./2006)

  13. Comparison between Experiment and Simulation(290 MeV/u) Bragg Peak SOBP (Spread-Out Bragg Peak) w/ Ridge Filter tends to underestimate the tail effect coming from beam fragments offset=-1mm offset=-0.8mm Geant4 Physics Verification and Validation (17-19/Jul./2006)

  14. Comparison between Experiment and Simulation(400 MeV/u) Bragg Peak SOBP w/ Ridge Filter tends to underestimate the tail effect coming from beam fragments offset=-1.2mm slight inconsistency in offset values? offset=-2.8mm Geant4 Physics Verification and Validation (17-19/Jul./2006)

  15. Tail Effect – more in detail Binary Cascade 290MeV/u 40oMeV/u Bragg Peak SOBP Tail effect is underestimated by 10-20%. Geant4 Physics Verification and Validation (17-19/Jul./2006)

  16. Summary • A joint project among Geant4 developers and medical physicists in Japan is on-going. • Physics validation in medical application (particle therapy) is a critical issue. • A new test beam line in HIMAC was constructed, and experimental data was obtained. It is a good chance to validate Geant4 ion physics. • Geometry of the test beam line was implemented in Geant4, and comparisons with simulation were carried out. • We tried the Binary Cascade model and the JQMD model for describing ion interactions. • Overall profile of the Bragg peaks are well reproduced by Geant4 simulation. • … but, we found a problem with the Binary Cascade model in our problem domain. We hope that it will be improved. • The tail effect coming from ion fragments is not fully reproduced. Geant4 tends to underestimate the effect. There are some space to be improved. Geant4 Physics Verification and Validation (17-19/Jul./2006)

  17. Acknowledgements • T.Sasaki, K.Amako, G.Iwai (KEK) • T.Aso (TNCMT) • A.Kimura (Ashikaga Univ.) • T. Koi (SLAC) • M.Komori, T.Kanai, N.Kanematsu, Y.Kobayashi, S.Yonai (NIRS), • Y.Kusano, T.Nakajima, O.Takahashi (AEC) • M.Tashiro (Gunma Univ.) • Y.Ihara, H.Koikegami (IHI) • supported by Geant4 Physics Verification and Validation (17-19/Jul./2006)

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