Cancer treatment without use of a nuclear reactor. Development of the accelerator for BNCT

In boron neutron capture therapy (BNCT), the use of a nuclear reactor is lack of simplicity as a therapeutic device. For this reason, Ibaraki BNCT (iBNCT) is under development at Tokai village, Ibaraki Prefecture, as a medical device aiming for accelerator-based BNCT. This paper reviewed the features of accelerator as a compact accelerator-based strong neutron source. First, it explained the principle of BNCT and basic requirements for accelerator based on the principle. The feature of the accelerator for BNCT is that it is a high power accelerator. Blistering caused when protons accelerated to a certain degree hit a substance becomes a big problem as the current becomes large. The overall structure of iBNCT accelerator is illustrated. The beams emitted from an ion source are made incident to a quadrupole linear accelerator for acceleration, further accelerated with a drift tube linac, and emitted. The combination of proton beams and beryllium target is a very good combination from the viewpoint of residual radioactivity. The iBNCT continues beam conditioning operation and measurement/testing toward treatment. Blistering can probably be prevented by a three-layer structure for function separation. However, considering large current exceeding 1 mA on average, it is necessary to carefully watch the proceedings. (A.O.)