Beam performance of the iBNCT as a compact linac-based BNCT neutron source developed by University of tsukuba

Abstract

Boron neutron capture therapy (BNCT) is emerging as the next-generation radiation therapy, thanks to the recent technological advancements in the accelerator-based neutron source. In the iBNCT project headed by the University of Tsukuba, a linac-based BNCT device is being developed. The demonstrator of the iBNCT device commenced its operations in 2016. This paper reports the various experiments and measurements performed on the iBNCT device to confirm the physical characteristics of the neutron beam emitted from the beam aperture of the device. We evaluated the neutron energy spectrum at the beam aperture experimentally using the Bonner sphere detector method. The results demonstrated that the device emits the epithermal neutron beam corresponding with the energy spectrum assumed in the design phase. Furthermore, we performed experiments using a water phantom that simulates a human body whereby we measured the profiles of both thermal neutron flux and gamma-ray dose rate on the beam axis in the phantom. The results demonstrated that the iBNCT neutron beam has sufficient intensity applicable to clinical studies of the BNCT. In order to apply the iBNCT device to real-time therapy, we perform the device development on a continuous basis to further improve the stability performance as well as to increase proton current.