Neutron and photon calculations of beam shaping assembly for BNCT based on Monte Carlo-discrete ordinates coupled method

Abstract The radiation field parameters at the beam shaping assembly (BSA) exit port are the key to boron neutron capture therapy (BNCT) treatment. However, obtaining calculation results with high efficiency and accuracy using only Monte Carlo (MC) method or discrete ordinates (S N ) method is difficult. Based on NECP-MCX code and Marvin code, this paper implemented the Monte Carlo-discrete ordinates coupled method and applied this method to the calculation of the radiation field at the BSA exit port. The effect of mesh grid division, the order of quadrature set, and the bias of quadrature set on the results of the coupled calculation was studied. It was concluded that the order and bias of the quadrature set have not improved the coupled calculation results. It was found that the data library used in the S N calculation is the main cause. Therefore, the Monte Carlo-discrete ordinates coupled method can be quickly and accurately applied to the calculation of the radiation field at the BSA exit port by dividing the energy and coordinate intervals rationally and using a more suitable cross section library.