¹⁰B Concentration, Phantom Size and Tumor Location Dependent Dose Enhancement and Neutron Spectra in Boron Neutron Capture Therapy

Background: The amount of average dose enhancement in tumor loaded with ¹⁰B may vary due to various factors in boron neutron capture therapy.

Objective: This study aims to evaluate dose enhancement in tumor loaded with ¹⁰B under influence of various factors and investigate the dependence of this dose enhancement on neutron spectra changes.

Material and methods: In this simulation study, using ²⁵²Cf as a neutron source, the average in-tumor dose enhancement factor (DEF) and neutron energy spectra were calculated for various ¹⁰B concentrations, phantom with different sizes and for different tumor locations, through MCNPX code.

Results: Obtained results showed that the values of average DEF rise with increasing ¹⁰B concentration, phantom diameter (˂ 30 cm) and tumor distance from the source, but this increment is not linear.

Conclusion: It was concluded that inequality in average dose enhancement rates, in tumor loaded with ¹⁰B under influence of various factors in boron neutron capture therapy, is due to non-identical changes of both the thermal neutron flux with increasing same number of ¹⁰B atoms and same thickness of scattering material, and the thermal to fast neutron flux ratio with increasing equal distances of tumor from the source.