Neutronics Analyses of the Radiation Field at the Accelerator-Based Neutron Source of Nagoya University for the BNCT Study

Abstract

The Nagoya University Accelerator-driven Neutron Source (NUANS) is an accelerator-based neutron source by 7Li(p,n)7Be reaction with a 2.8 MeV proton beam up to 15 mA. The fast neutrons are moderated and shaped to beam with a Beam Shaping Assembly (BSA). NUANS is aiming at the basic study of the Boron Neutron Capture Therapy (BNCT) such as an in vitro cell-based irradiation experiment using a water phantom. Moreover, the BSA is developed as a prototype of one for human treatment. We have evaluated the radiation field of NUANS by a Monte Carlo code PHITS. It is confirmed that the radiation characteristics at the BNCT outlet meet the requirement of IAEA TECDOC-1223. Additionally, the radiation field in the water phantom located just in front of the BSA outlet is calculated. In the in vitro irradiation experiment, the boron dose of 30 Gy-eq, which is the dose to kill tumor cells, is expected for 20 min of irradiation at the beam current of 15 mA.