加速器をベースとしたホウ素中性子捕捉療法施設の開発～いばらきBNCT計画に即して～

抄録

An accelerator-based BNCT（Boron Neutron Capture Therapy）facility is being constructed at the Ibaraki Neutron Medical Research Center. It consists of a proton linac（8 MeV energy and 10 mA average current), a beryllium target, and a moderator system to provide an epi-thermal neutron flux for patient treatment. The technology choices for this present system were driven by the need to site the facility in a hospital and where low residual activity is essential. The maximum neutron energy produced from an 8 MeV-proton is 6 MeV, which is below the threshold energy of the main nuclear reactions which produce radioactive products. The down side of this technology choice is that it produces a high density heat load on the target so that cooling and hydrogen blistering amelioration prevent sever challenges requiring successful R&D progress. The latest design of the target and moderator system shows that a flux of 2.5×10⁹ epi-thermal neutrons/cm²/sec can be obtained. This is two times higher than the flux from the existing nuclear reactor based BNCT facility at JAEA（JRR-4).