Design and optimization of two-sided beam based on ~7Li(p,n)~7 Be source using in BNCT for brain and liver tumors

摘要

Recent studies in BNCT have focused on investigating appropriate neutron sources based on accelerators. One of the common reactions based on accelerators for neutron production is Li-7(p,n)Be-7. In this paper we designed and optimized two-sided Beam Shaping Assembly composed of a moderator, a filter, a reflector and a collimator for the perpendicular neutrons with respect to the direction of the incident beam to provide an appropriate neutron beam in BNCT. Calculations for our design show, using a proton beam of 2.5 MeV with a current of 10 mA, will produce proper epithermal neutron flux in both sides of the system. The final optimized flux for the system was calculated to be 2.15 x 10(9) n/cm(2).s for one side of BSA and the epithermal neutron flux on one of two sides has increased by about 32% with respect to the forward direction. All in-air licensed parameters proposed by the International Atomic Energy Agency (IAEA) have been established. The dose evaluation results and depth dose curves were presented for a simulated head phantom and a human phantom including the liver with a typical tumor. The results confirmed that the designed neutron source and BSAs, can potentially be used to treat deep-seated brain and liver tumors in BNCT.