A Neutronic Study of an Accelerator-Based Neutron Irradiation Facility for Boron Neutron Capture Therapy

Abstract
A neutronic study of an accelerator-based neutron irradiation facility (ANIF) for boron neutron capture therapy (BNCT) was performed using three-dimensional Monte Carlo transport calculations. The major components of the ANIF are a radio-frequency quad-rupole proton accelerator, a 7Li target, and a moderator assembly. Neutrons are generated by bombarding the 7Li target with 2.5-MeV protons. The neutrons emerging from the 7Li target are too energetic to be used for BNCT and must therefore be moderated.Calculations show that, among all materials for the ANIF, beryllia (BeO) and heavy water (D2O) are the best moderators. Between them, beryllia provides better neutron spectra, but D2O gives higher neutron intensities. Adding alumina (Al2O3) to D2O improves the neutron spectra, but it also increases gamma-ray contamination.The overall performance of an ANIF was evaluated for a moderator assembly composed of a 20.0-cm-high x 12.5-cm-radius beryllia cylinder reflected by 30.0 cm of alumina. Calculations ...