Experimental validation of a newly developed neutron ambient dose H* detector in an accelerator-based BNCT field

Out-of-field neutron dose evaluation is important for radiation protection during boron neutron capture therapy (BNCT). However, no commercial detector is available for measuring the neutron ambient dose equivalent H* outside the irradiation field. Establishing a reliable H* evaluation method is essential for the international standardization of BNCT. In this study, a prototype neutron detector was evaluated using a cyclotron-based epithermal neutron source (C-BENS). The ratio of the measured to calculated H*, based on ICRP Publication 116, ranged from 0.21–0.56 at lateral distances of 10–150 cm from the beam aperture center. This discrepancy is likely due to the difficulty in accurately reproducing the experimental geometry in the Monte Carlo simulation used to calculate the reference H*. These results provide a basis for improving H* evaluation methods and developing standardized radiation protection procedures for BNCT.