Abstract :
Due to the selectively treating tumors and largely sparing normal neighboring cells, Boron Neutron Capture Therapy (BNCT) continues to be of special significance and interest for wide groups of researchers. One of the most important challenges in this context is to design an optimized beam based on an appropriate neutron source. The recent studies, focused on investigating neutron sources as alternatives for nuclear reactors, revealed the high potential of electron linacbased photoneutron sources to improve the efficiency of this treatment method. Inquiring about the efficiency of a layered model of beam shaping assembly (BSA) for photoneutron sources to be used in BNCT of deep tumors is the main subject of this simulation study. This model, unlike the traditional BSA in which the reflector surrounds the whole moderator, includes many concentric cylinders of reflectors and moderators. The MCNPX simulations for various primary energies show that the layered model results in more appropriate beam characteristics compared with that of the common geometry. Moreover, the parameters governing the beam properties such as the thickness of the layers, moderator/reflector and collimator lengths, and the thickness of the surrounding reflector have been investigated. The results are encouraging and offer new ways to accomplish more researches in studies on the BNCT technique.
