| Budget Amount *help |
¥24,310,000 (Direct Cost: ¥18,700,000、Indirect Cost: ¥5,610,000)
Fiscal Year 2019: ¥5,460,000 (Direct Cost: ¥4,200,000、Indirect Cost: ¥1,260,000)
Fiscal Year 2018: ¥7,410,000 (Direct Cost: ¥5,700,000、Indirect Cost: ¥1,710,000)
Fiscal Year 2017: ¥11,440,000 (Direct Cost: ¥8,800,000、Indirect Cost: ¥2,640,000)
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| Outline of Final Research Achievements |
The problem of "secondary exposure" is becoming more serious in proton beam therapy for cancer treatment. The proton beam reacts with the metal collimator when it is focused, and it also produces a large amount of fast neutrons in the patient's body. These incidental doses cannot be accurately evaluated by the current treatment system and cannot be reflected in the treatment plan. In this research, we developed an innovative imaging method for fast neutrons, and succeeded in imaging with a proton beam that mimic the actual treatment site. Specifically, we fabricated an array type detector consisting of two layers of waveform discrimination type plastic scintillator, and estimated the neutron arrival direction from the kinematics of elastic scattering. We tried to estimate the dose equivalent using the G(E) function method from the acquired neutron images. We conclude that about 1/100 of the the primary proton dose is given by fast neutrons during the proton therapy.
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