Of Bnct Monte Carlo Simulation Method And Software Development

Boron neutron capture therapy (BNCT) technique is used in treating brain tumors by artificially loading the tumor tissue with isotope Boron enriched compound and subsequently irradiation of brain by low energy neutrons. The technique is based on the ¹⁰B(n,α)⁷Li nuclear reaction emitting alpha particle and Li nuclei with total kinetic energy of 2.79 MeV, which is high enough to destroy the tumor cells and avoids to hurt the normal tissue.Development of a physical dosimetry simulation tool is a key of BNCT treatment planning software. Many BNCT commercial softwares have been developed in abroad. These softwares are very high in cost and the key techniques keep in secret. BNCT software involves the preprocessor, a coupled of neutron and photon transport and post-processor. Due to the complicated geometries, the Monte Carlo (MC) method is usually chosen as the simulation method. Hovever, the large amount of particle histories need to be simulated and take so much time if the tradional MC method is used to simulate the dosimetry, it is very difficulty to be accepted accordind to the clinical requirement.Our research focuses on development of an algorithm which not only keeps the accurace,but also short the computational time. Firstly, the MCNP code is used to simulate three international benchmark model, the results are compared with the results of modified Snyder phantom geometry model. Then, a center point method, which is based on the four basic materials, good the mass conservation, a less memory and easily produces the input files, is developed. The results show that the modified voxel models keep the same accuracies with benchmark voxel models. Followly, the combinated mesh models are designed according to the depth-dose-rate distribution. A 5mm optimal mesh model is obtained. These models greatly decrease the computational time in the statistical uncertainty being kept constant. In addition, the relationship of particle histories, accuracy and computational time is studied. Finally, a fast particle tracking technique and intersection point treatment are developed. The computational efficiency is high about 30% than that of MCNP code. The present BNCTsoftware is already with the value of clinical application.