Clinical trials of the boron neutron capture therapy (BNCT) have been conducted using research reactors. Recent progresses in the accelerator and accelerator-driven-neutron-source technologies have rendered it possible to generate the substantial number of neutrons required for BNCT treatment, using a compact accelerator, which can be installed in a hospital. The University of Tsukuba launched a project for the development of a compact accelerator-based neutron source for BNCT. For this

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... tor, we employed a linear particle accelerator (linac) and the energy of the proton beam was 8 MeV. Beryllium was selected as the neutron target material. To generate sufficient neutron intensity by the reaction between 8 MeV protons and beryllium, the linac accelerates a high current of 5 mA or more. As the target system is critical, we developed a beryllium target system with a threelayered structure to avoid target breakage, caused by massive heat load and blistering, within a short period. The linac-based neutron source for the BNCT is almost complete and we succeeded in generating neutrons, in 2015. Currently, several characteristic measurements are being carried out.