Results from the recent carbon test beam at

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Results from the recent carbon test beam at HIMAC Koichi Murakami Statoru Kameoka KEK

Results from the recent carbon test beam at HIMAC Koichi Murakami Statoru Kameoka KEK CRC Koichi Murakami Geant 4 Physics Verification and Validation (17 -19/Jul. /2006) supported by 1

Introduction n A joint project among Geant 4 developers, astrophysicists and medical physicists in

Introduction n A joint project among Geant 4 developers, astrophysicists and medical physicists in Japan ü 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 n The project goal ü 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 ü In addition, physics validation is one of key issues. Koichi Murakami Geant 4 Physics Verification and Validation (17 -19/Jul. /2006) 2

Physics Validation in Radiotherapy n Geant 4 has to reproduce precise dose distributions in

Physics Validation in Radiotherapy n Geant 4 has to reproduce precise dose distributions in human body. ü which requires correct simulation for the interactions between various types of beams (X-ray, proton, heavy ions) and materials along beam line ü reliable descriptions of ≫electromagnetic processes ≫hadronic/nuclear processes ≫nuclear decay processes in the relevant energy regions and particle types. ü These are non-trivial issues! n Physics validation is one of the most critical aspects in the project. Koichi Murakami Geant 4 Physics Verification and Validation (17 -19/Jul. /2006) 3

Hadrontherapy Facilities in Japan Jpn (world) # Proton beam facilities: 5 (23) # Ion beam

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

HIMAC at NIRS n. Operation since 1994 n. Treatment beam: 12 C n. Over

HIMAC at NIRS n. Operation since 1994 n. Treatment beam: 12 C n. Over 2, 000 patients have been treated Ion Source Experiment Areas RFQ Linac 800 Ke. V/u Alvarez Linac 6 Me. V/u Synchrotron 800 Me. V/u Treatment Rooms ~65 m Koichi Murakami Geant 4 Physics Verification and Validation (17 -19/Jul. /2006) 5

Hadron (proton/carbon) Beam Ref. http: //www. nirs. go. jp/tiryo/himac 2. htm n A sharp

Hadron (proton/carbon) Beam Ref. http: //www. nirs. go. jp/tiryo/himac 2. htm n A sharp peak of energy deposition at the end of the range (Bragg peak) n The sharp fall-off of the Bragg peak for carbon beam Relative Dose (%) 100 X-ray g-ray neutron 50 ü A small range straggling n Carbon produces a longer tail after the Bragg peak. proton carbon 0. 0 5. 0 10. 0 Depth - Human Body (cm) 15. 0 Hadron beams allow conformation of dose distribution better than photons and electrons; Koichi Murakami Geant 4 Physics Verification and Validation (17 -19/Jul. /2006) 6

Conformation of Irradiation Field Collimator Wobbler magnets X Y Scatterer Ridge Filter Range Shifter

Conformation of Irradiation Field Collimator Wobbler magnets X Y Scatterer Ridge Filter Range Shifter Patient body Target volume (tumor) Beam Compensator (Bolus) By = Ay sin(wt) Bx = Ax sin(wt+p/2) dose Spiral beam divergence to create a uniform irradiation field Koichi Murakami Ridge Filter Bragg peak Depth Geant 4 Physics Verification and Validation (17 -19/Jul. /2006) Spread-out Bragg peak (SOBP) 7

Experimental Setup Beam Energy 290, 400 Me. V/u Vacuum window Wobber magnets X Y

Experimental Setup Beam Energy 290, 400 Me. V/u Vacuum window Wobber magnets X Y Secondary emission monitor Dose Monitor (ionization Chamber) Scatterer (lead) Range shifter (unused) Collimator Beam 12 C Multi-leaf Collimator (open) Collimator Acrylic vessel Water target Ridge filter Beam profile Treatment position Monitor (aluminum) (ionization (isocenter) Chamber) Test beam line of HIMAC(NIRS) Koichi Murakami Geant 4 Physics Verification and Validation (17 -19/Jul. /2006) 8

Water target / Scored region • Dose distribution in a water target was measured

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 1 mm. • scanning along the depth direction Water target 2 mm Scored region 1 mm 2 mm Koichi Murakami Beam (12 C) 400 mm Geant 4 Physics Verification and Validation (17 -19/Jul. /2006) 9

Physics List n Generic Ions ü elastic scattering ü Binary light ion cascade or

Physics List n Generic Ions ü elastic scattering ü Binary light ion cascade or JQMD ≫cross section : Tripathi / Shen ü radioactive decay ü ionization / multiple scattering n Hadron ü elastic scattering ü L(H)EP+Binary cascade ü ionization / multiple scattering n electron/gamma ü standard EM Koichi Murakami Geant 4 Physics Verification and Validation (17 -19/Jul. /2006) 10

Bragg Peak Simulation (Binary Cascade) 290 Me. V/u • Overall profile of Bragg peak

Bragg Peak Simulation (Binary Cascade) 290 Me. V/u • Overall profile of Bragg peak seems to be well reproduced, but… • We found a small bump just before the peak… What is this!? 40 o. Me. V/u Koichi Murakami Geant 4 Physics Verification and Validation (17 -19/Jul. /2006) 11

Bragg Peak – more in detail BC JQMD • Secondaries of 11 C produce

Bragg Peak – more in detail BC JQMD • Secondaries of 11 C produce the bump of BC. • JQMD shows no bump. • Production rates of 11 C (one neutron stripped off) and 11 B (one proton stripped off) are different between Binary Cascade and JQMD. • Production rate of 11 C in BC is over created. Koichi Murakami Geant 4 Physics Verification and Validation (17 -19/Jul. /2006) 12

Comparison between Experiment and Simulation (290 Me. V/u) Bragg Peak SOBP (Spread-Out Bragg Peak)

Comparison between Experiment and Simulation (290 Me. V/u) Bragg Peak SOBP (Spread-Out Bragg Peak) w/ Ridge Filter tends to underestimate the tail effect coming from beam fragments offset=-0. 8 mm Koichi Murakami offset=-1 mm Geant 4 Physics Verification and Validation (17 -19/Jul. /2006) 13

Comparison between Experiment and Simulation (400 Me. V/u) Bragg Peak SOBP w/ Ridge Filter

Comparison between Experiment and Simulation (400 Me. V/u) Bragg Peak SOBP w/ Ridge Filter tends to underestimate the tail effect coming from beam fragments offset=-1. 2 mm slight inconsistency in offset values? Koichi Murakami offset=-2. 8 mm Geant 4 Physics Verification and Validation (17 -19/Jul. /2006) 14

Tail Effect – more in detail Binary Cascade 290 Me. V/u 40 o. Me.

Tail Effect – more in detail Binary Cascade 290 Me. V/u 40 o. Me. V/u Bragg Peak SOBP Tail effect is underestimated by 10 -20%. Koichi Murakami Geant 4 Physics Verification and Validation (17 -19/Jul. /2006) 15

Summary n A joint project among Geant 4 developers and medical physicists in Japan

Summary n A joint project among Geant 4 developers and medical physicists in Japan is on-going. ü Physics validation in medical application (particle therapy) is a critical issue. n A new test beam line in HIMAC was constructed, and experimental data was obtained. It is a good chance to validate Geant 4 ion physics. ü Geometry of the test beam line was implemented in Geant 4, and comparisons with simulation were carried out. ü We tried the Binary Cascade model and the JQMD model for describing ion interactions. ü Overall profile of the Bragg peaks are well reproduced by Geant 4 simulation. ü … but, we found a problem with the Binary Cascade model in our problem domain. We hope that it will be improved. ü The tail effect coming from ion fragments is not fully reproduced. Geant 4 tends to underestimate the effect. There are some space to be improved. Koichi Murakami Geant 4 Physics Verification and Validation (17 -19/Jul. /2006) 16

Acknowledgements n n n n n T. Sasaki, K. Amako, G. Iwai (KEK) T.

Acknowledgements n n n n n 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 Koichi Murakami Geant 4 Physics Verification and Validation (17 -19/Jul. /2006) 17