Boron Neutron Capture Therapy Dose Calculation for Tumor Modified Snyder Head Phantom Using MCNP

For obtaining the depth-dose curves in tumor modified Snyder head phantom for series energy neutrons for boron neutron capture therapy （BNCT）, and optimizing the energy distribution of source neutron, ultimately, getting a better understanding of the principle of BNCT, MCNP was used for calculating the boron dose, thermal neutron dose, epithermal and fast neutron dose, induced photon dose and the total relative biologic effectiveness (RBE) dose in tumor modified Snyder head phantom for series energy neutrons, including 0.025 3 eV, 1 eV, 1 keV, 10 keV, 100 keV and 1 MeV. The results show that boron dose in superficial tissue of neutron is higher than in the tumor area; fast neutron has a small boron dose deposition in all depths, nevertheless, its epithermal and fast neutron dose is too high; epithermal neutron has a suitable penetrating ability, deposits a relatively high boron dose and total RBE dose in the target tumor area. It can conclude that epithermal neutron has a good BNCT curative effectiveness; thermal and fast neutrons are not good enough for BNCT use.