Evaluating Epithermal Neutron Energy Levels for Optimized Neutron Capture in Cancer Therapy

Abstract

Neutron flux measures neutron radiation intensity, essential in Boron Neutron Capture Therapy (BNCT). The neutron flux is a crucial parameter as it affects the availability of neutrons required to initiate boron-neutron capture reaction in BNCT. Epithermal neutron energies are recommended for BNCT ranging from 1 eV to 10 keV. However, towards the upper limit of epithermal neutron energy range the neutron flux decreases which is not desirable for the treatment. So in this study, neutron flux in soft tissue were evaluated using PHITS (A Monte Carlo simulation) for optimized neutron capture. The phantom consists of soft tissue with a concentration of 30ppm of Boron-10 and irradiated with 5 keV, 6 keV, 7 keV, and 8 keV of neutron energy for achieving minimized skin absorbed dose and maximize the absorbed dose to the depths of the phantom. The simulation demonstrates that the distribution of neutron interaction spanning from the target’s surface to its depth shows substantial capture of neutrons at the target’s volume. The energy of 7 keV yields an effective neutron thermal flux that aligns favorably with the goal of BNCT that facilitating efficient neutron capture by Boron-10 without generating excessive fast neutrons or undesirable gamma radiation.