Directional Sensitivity Analysis of an Epithermal Neutron Flux Monitor for In-Vivo Real-Time Dosimetry in Boron Neutron Capture Therapy

Le résumé fourni par la source

Boron Neutron Capture Therapy (BNCT) is a promising form of radiotherapy that enables the selective destruction of tumor cells with minimal damage to surrounding healthy tissue. In BNCT, epi-thermal neutrons are irradiated onto tumor sites where10B has been selectively accumulated, producing high-LET alpha particles and7Li nuclei that act within individual cells [1]. Given the high dose of epi-thermal neutrons prescribed in BNCT, developing a reliable dose monitoring system is critical from an engineering point. Due to the dynamic nature of boron distribution, realtime dose verification is preferred over indirect estimations. To address this, our research group has developed an absolute neutron intensity monitor based on a LiCaF scintillator, taking advantage of lithium's high cross section and linear response to epi-thermal neutrons [2]. We prepared three LiCaF scintillators, each equipped with moderator layers of different thicknesses and materials, for instance, boron, cadmium, and boron nitride, to correct response variations arising from cross-section non-uniformity. This setup enables indirect estimation of10B reaction rates via neutron flux measurement. While a validation experiment was conducted, discrepancies were observed between simulation and experimental data, primarily due to neutron scattering. As this impacts the precise estimation of the absolute neutron flux intensity, this study investigates an improved moderator design. Instead of conventional box moderators, spherical moderators with various thicknesses were applied around the scintillators to ensure consistent neutron shielding from all incident angles. Monte Carlo simulations were used to evaluate the angular response uniformity of the monitors. Results showed this modified system achieved isotropic response both for neutron beams parallel to the x-axis and those incident at a 45° angle, demonstrating its potential for reliable, direction-independent absolute neutron flux monitoring.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.