iBNCT Project ct Verification of dose estimation for Monte- Carlo based treatment planning system for boron neutron capture therapy H. Kumada , K. Takada, T. Aihara, A. Matsumura H. Sakurai, T. Sakae Proton Medical Research Centre, University of Tsukuba
iBNCT Project ct Progress of boron neutron capture therapy (BNCT) Boron neutron capture therapy (BNCT) is based on the nuclear reaction that occurs when boron-10 is irradiated with neutrons of the appropriate energy to produce high-energy alpha particles and recoiling lithium-7 nuclei. Therefore BNCT is categorized to external beam therapy using neutron beam . Clinical trials for BNCT is being performed using research rectors so far. However in recent years, many accelerator-based neutron sources for BNCT are being developed . In Japan in particular, some devices have been generated enough neutrons , and two facilities are already being carrying out clinical trials using cyclotron-based neutron source for BNCT . University of Tsukuba is also developing a linac-base BNCT device. BNCT facilities in Japan Kyoto University Southern Tohoku BNCT Research National Cancer Center Research Reactor University of Tsukuba (Ibaraki) Center (Fukushima) Hospital (Tokyo) Institute (Osaka)
iBNCT De Develop lopment ent of Pe Peripher heral al Eq Equipment ent for BN BNCT Project ct 《 Neutron Monitor 》 《 Patient Positioning System 》 と中性子反応で生じる即発γ線 《 PG-SPECT 》 中性子遮蔽壁 即発γ線検出器 中性子ターゲット 陽子線 中性子 Treatment room スペクトル可変機構 Neutron Proton Beam Beam 《 Beam Transport System 》 【 Treatment Management System 】 《 Beryllium 即発 γ 線 ベース・リアルタイム３ 線量モニター Target 》 《 Neutron Generator 》 Linac 【 RFQ+DTL Type Linac for BNCT 】 【 Treatment Planning System 】 Not only neutron generator with accelerator but also peripheral devices which are needed to perform BNCT, are being developed. Monte-Carlo based treatment planning system Patient positioning system by using motion capture technology Real-time neutron monitor, PG-SPECT etc.
iBNCT Project ct Dose estimation process with Tsukuba-Plan Set Region of Interest Set Irradiation Set Material Condition Monte-Carlo Calculation Dosimetry Mode
iBNCT Fe Feature ures of Ts Tsuku kuba-Pla Plan Project ct Tsukuba-Plan has employed “ PHITS ” as the dose calculation engine. PHITS is multi-purpose MC transport code, and it can determine doses for neutrons, photons as well as protons, heavy ions . Therefore Tsukuba-Plan with PHITS enables to perform dose estimation for not only BNCT but also for external beam therapies as particle therapy and X-ray therapy. And it is also adaptable to brachytherapy . ➡ Dose estimation/treatment planning for each radiotherapy ➡ Treatment planning for combined radiotherapy ➡ Dose estimation for total dose given to a patient And Tsukuba-Plan allows to estimate incidental dose caused by secondary neutrons in particle therapy. Furthermore, PHITS has “ MKM ” which can perform micro-dosimetry . Thus Tsukuba-Plan can determine equivalent dose based on “ RBE micro-dosimetry in addition to conventional way as x Physical dose ”
iBNCT Project ct Application of Tsukuba Plan to Proton therapy and X-ray therapy X-ray Therapy 6 MV Ridge filter Irradiation field: 5 cm × 5 cm Bolus 1 st scatterer X-ra y Bea m T arget 120.0% Measured data 120.0% D i r e c t i o n Region Measured data PHITS calculation 100.0% 100.0% PHITS calculation Relative dose Relative dose 80.0% 80.0% 60.0% 60.0% 2 nd Middle 40.0% 40.0% scatterer collimator 20.0% 20.0% 0.0% 0.0% 0.0 100.0 200.0 MLC Head phantom -80.0-60.0-40.0-20.0 0.0 20.0 40.0 60.0 80.0 Proton therapy in University Depth in water (mm) Distance from the beam axis(mm) Two-field fractionated Dose estimation for proton therapy of Tsukuba Hospital Comparison results of PDD and OCR for 6-MV beam X-ray irradiation Proton Secondary neutron dose estimation in Proton therapy 120.0% Therapy 100.0% Rela tive dose 80.0% 60.0% Snout 120, MD 90 (Center of SOBP) 120% 40.0% Measurement data 100% Target 80% 20.0% Relative dose (%) PHITS calculation Region 60% 0.0% 40% Measurement 0.0 50.0 100.0 150.0 20% PHITS calculation Depth in water (mm) 0% -50 -40 -30 -20 -10 0 10 20 30 40 50 Distance from the beam axis (mm) SOBP:40 mm Measure Depth:90 mm 2D dose distribution Proton dose distributions Secondary neutron dose distributions Poster No. 124: H. Kumada, et al., “Application expansion of the Monte-Carlo based treatment planning Poster No. 125: K. Takada, et al., “Fundamental study for practical application of radiotherapy treatment system for BNCT to particle radiotherapy and X-ray therapy.” planning system capable of evaluation neutron dose generated by various radiotherapy beams.”
iBNCT Project ct Verification for the dose estimation performance of Tsukuba Plan for boron neutron capture therapy (BNCT)
iBNCT Project ct Verification in all BNCT facilities in Japan Tsukuba Plan University of Tsukuba, iBNCT Facility Southern Tohoku Hospital, BNCT Center Irradiation room Accelerator National Cancer Center Hospital Kyoto University KUR, BNCT facility
iBNCT Create three neutron source for BNCT Project ct Water Phantom Water Phantom JRR-4 in JAEA KUR in Kyoto University Research Reactor グラフ タイトル 3.5E+09 Experimental Values Thermal Neutron Flux (n/cm 2 s) 3.0E+09 Tsukuba Plan Calculations Water phantom Beam Port 2.5E+09 2.0E+09 1.5E+09 1.0E+09 5.0E+08 0.0E+00 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 Depth from phantom surface (cm) iBNCT accelerator-based neutron source for BNCT in University of Tsukuba Thermal neutron flux distributions in a cylindrical water phantom
iBNCT Project ct Verification (2) in iBNCT accelerator-based neutron source Dose estimations by using Tsukuba Plan Experiments in iBNCT facility To confirm characteristics of neutron in Univ. Tsukuba beam emitted from beam aperture, several experiments with a water phantom had been carried out. For measurement of thermal neutron flux distribution , some gold wires and Calculation Model gold foils were set inside the phantom, 3D-Model of water phantom Compare Water phantom experiments and the distributions were measured. 1.2E+08 Some scintillators detectable thermal 1.0E+08 金箔実験値 LiCAF 実験値 neutrons were also located in the 8.0E+07 モンテカルロ計算値 熱中性子束 （ n/cm 2 ・ｓ） 6.0E+07 phantom. 4.0E+07 For gamma-ray dose distribution , 2.0E+07 many TLD s were set in the phantom, 0.0E+00 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 Phantom 表面からの深さ （ cm ） and measured the gamma-ray dose 陽子電流：平均 Ａ 水ファントム実験結果 Experimental values for distribution. thermal neutron flux Thermal neutron flux distributions
iBNCT Project ct Comparison with Tsukuba-Plan Calculations and Experiments Calculation time 9.0E+08 4.0E+00 8.0E+08 Calculations 3.5E+00 7.0E+08 Intel Xeon E5 Measurements Thermal Neutron Flux (n/cm 2 s) 3.0E+00 Gamma-ray dose rate (Gy/h) 6.0E+08 32 Core Workstation X 3 2.5E+00 5.0E+08 2.0E+00 4.0E+08 1.5E+00 = 90 Core parallel computing Calculation 3.0E+08 Normalization point: 1.0E+00 Measurements 2.0E+08 Depth: 5cm 5.0E-01 1.0E+08 0.0E+00 Calculation time : about 18 min . 0.0E+00 0.0 2.0 4.0 6.0 8.0 10.0 0.0 2.0 4.0 6.0 8.0 10.0 Depth from surface (cm) Depth from surface (cm) Beam central axis Beam central axis (statistical errors around target region < 5% ) Calculation Surface Calculations Surface Calculations Surface 4.0E+00 Measurements Surface 5.0E+08 5.0E+08 Depth: 2cm Measurements Surface Measurements Surface Calculation Depth 2cm 4.5E+08 4.5E+08 3.5E+00 Calculations Depth 0.5cm Calculations Depth 0.5cm Measurements Depth 2cm 0.5 Meaurements Depth 0.3cm Meaurements Depth 0.3cm 4.0E+08 4.0E+08 Calculation Depth 2cm 10 Gamma-ray dose rate (Gy/h) Thermal Neutron Flux (n/cm 2 s) Thermal Neutron Flux (n/cm 2 s) 3.0E+00 Measurements 10cm 3.5E+08 3.5E+08 2.5E+00 3.0E+08 3.0E+08 Depth from surface: 0.5cm Depth from surface: 0.5cm surface 2.0E+00 2.5E+08 2.5E+08 2.0E+08 2.0E+08 1.5E+00 1.5E+08 1.5E+08 1.0E+00 1.0E+08 1.0E+08 surface surface 5.0E-01 Depth: 10cm 5.0E+07 5.0E+07 0.0E+00 0.0E+00 0.0E+00 0.0 0.0 2.0 2.0 4.0 4.0 6.0 6.0 8.0 8.0 10.0 10.0 0.0 2.0 4.0 6.0 8.0 10.0 Distance from center (cm) Distance from center (cm) Distance from center (cm) Lateral distributions Lateral distributions Thermal neutron flux distributions Gamma-ray dose rate distributions
iBNCT Project ct Dose estimation for realistic human model Set ROI and target point Set irradiation conditions Calculation models Calculation Results
iBNCT Influence for difference for beam sources, D.V.H. Project ct グラ フ タ イ ト ル 100 iBNCT Source ・ Tumor 90 KUR Source ・ Tumor 80 JRR4, 10cm port ・ Tumor 70 Volume （％） 60 JRR4, 12cm port ・ Tumor 50 iBNCT Left Brain 40 KUR Left Brain JRR-4 Left Brain 30 JRR412cmBeam Left Brain iBNCT Tumor 20 KUR Tumor JRR-4 Tumor 10 JRR412cmBeam Tumor 0 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 Dose （ Gy-Eq ）
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