Abstract: We introduce a simple method for voxel constructing and material ascertainment in BNCT(Boron Neutron Capture Therapy). The voxel model of a Snyder head phantom based on four materials, provides a good approximation. It keeps the conservation mass of skeletoncranium, brain and skin. The 4-material voxel model and 286-material voxel model with mesh sizes of 16 mm, 8 mm, 4 mm, are simulated respectively by the MCNP Monte. Carlo program. The result indicates that the 4-material voxel model is accurate. We also recommend a 5 mm mesh voxel model, which saves simulation time and keeps a good accuracy.

Key words: BNCT, Monte Carlo method, epithermal neutron, tumor, voxel model