Optimized therapeutic neutron beam for accelerator-based BNCT by analyzing the neutron angular distribution from 7Li(p,n)7Be reaction

Perpendicular neutrons (i.e., solid angle bin of 50–150°) among ones generated from 7Li(p,n)7Be reaction were used to produce an optimized therapeutic neutron beam for accelerator-based BNCT. A new beam port assembly was also designed to shape the fast neutrons into epithermal ones and to reduce unnecessary radiation including gammas. As a result of a simulation, it is found that a tumor at a depth of 60 mm from the head skin could be treated within 5 minutes, if a typical tumor is assumed to be taken about 20 RBE Gy for therapeutic treatment. It is, thus, expected that the neutrons emitted into the solid angle bin of 50–150° from 7Li(p,n)7Be reaction are very effective in producing epithermal neutron beams for BNCT.