design and simulation of photoneutron source by mcnpx monte carlo code for boron neutron capture therapy

introduction electron linear accelerator (linac) can be used for neutron production in boron neutron capture therapy (bnct). bnct is an external radiotherapeutic method for the treatment of some cancers. in this study, varian 2300 c/d linac was simulated as an electron accelerator-based photoneutron source to provide a suitable neutron flux for bnct. materials and methods photoneutron sources were simulated, using mcnpx monte carlo code. in this study, a 20 mev linac was utilized for electron-photon reactions. after the evaluation of cross-sections and threshold energies, lead (pb), uranium (u) and beryllium deuteride (bed2)were selected as photoneutron sources. results according to the simulation results, optimized photoneutron sources with a compact volume and photoneutron yields of 107, 108 and 109 (n.cm-2.s-1) were obtained for pb, u and bed2 composites. also, photoneutrons increased by using enriched u (10-60%) as an electron accelerator-based photoneutron source. conclusion optimized photoneutron sources were obtained with compact sizes of 107, 108 and 109 (n.cm-2.s-1), respectively. these fluxs can be applied for bnct by decelerating fast neutrons and using a suitable beam-shaping assembly, surrounding electron-photon and photoneutron sources.