A Project of Boron Neutron Capture Therapy System based on a Proton Linac Neutron Source

Abstract At present, the clinical trials of Boron Neutron Capture Therapy (BNCT) are being performed at research reactor facilities. However, an accelerator based BNCT has a merit that it can be built in a hospital. So, we just launched a development project for the BNCT based on an accelerator in order to establish and to spread the BNCT as an effective therapy in the near future. In the project, a compact proton linac installed in a hospital will be applied as a neutron source, and energy of the proton beam is planned to be less than about 10 MeV to reduce the radioactivity. The BNCT requires epithermal neutron beam with an intensity of around 1x109 (n/cm2/sec) to deliver the therapeutic dose to a deeper region in a body and to complete the irradiation within an hour. From this condition, the current of the proton beam required is estimated to be a few mA on average. Enormous heat deposition in the target is a big issue. We are aiming at total optimization of the accelerator based BNCT from the linac to the irradiation position. Here, the outline of the project is introduced and the moderator design is presented.