simulation of the bnct of brain tumors using mcnp code: beam designing and dose evaluation

introduction bnct is an effective method to destroy brain tumoral cells while sparing the healthy tissues. the recommended flux for epithermal neutrons is 109 n/cm2s, which has the most effectiveness on deep-seated tumors. in this paper, it is indicated that using d-t neutron source and optimizing of beam shaping assembly (bsa) leads to treating brain tumors in a reasonable time where all iaea recommended criteria are met. materials and methods the proposed bsa based on a d-t neutron generator consists of a neutron multiplier system, moderators, reflector, and collimator. the simulated snyder head phantom is used to evaluate dose profiles in tissues due to the irradiation of designed beam. monte carlo code, mcnp-4c, was used in order to perform these calculations.   results the neutron beam associated with the designed and optimized bsa has an adequate epithermal flux at the beam port and neutron and gamma contaminations are removed as much as possible. moreover, it was showed that increasing j/φ, as a measure of beam directionality, leads to improvement of beam performance and survival of healthy tissues surrounding the tumor. conclusion according to the simulation results, the proposed system based on d-t neutron source, which is suitable for in-hospital installations, satisfies all in-air parameters. moreover, depth-dose curves investigate proper performance of designed beam in tissues. the results are comparable with the performances of other facilities.