Subcellular dosimetry of the high linear energy transferred particles induced by boron neutron capture therapy

Boron Neutron Capture Therapy (BNCT), a binary radiotherapy technique that can be used to treat brain tumors, malign melanoma and head-neck cancer. These components are the 10B isotope that accumulates in biochemically targeted tumor cells and low-energy neutrons. The 10B isotope in tumor cells bombarded by low-energy neutrons releases high linear energy transfered alpha and lithium-7 particles with short range by means of 10B(n,α)7Li reaction to occur high localized dose to preferentially destroy tumor cells. The advantage of the Boron Neutron Capture Therapy is that the radiation effect could be limited only in tumor cells. The effectiveness of alpha and lithium-7 particles is in cellular dimensions due to their short ranges and high linear energy transfers, and is stochastic. Accordingly, microdosimetry is a suitable technique to investigate the stochastic energy deposition of these particles at cellular level. In the present study, ranges and stopping powers of alpha and lithium-7 particles were calculated by using theoretical approach, MATLAB program and GAMOS Monte Carlo simulation program, while dose and energy distributions were calculated for different BNCT agents by using GAMOS Monte Carlo simulation program in order to evaluate the effects and behaviors of alpha and lithium-7 particles induced by BNCT at subcellular level. Single and multi cell models were developed to calculate dose and energy distributions. Two different compounds were used for the chemical composition of the cell. By dividing the cell into four different spherical regions, considering the accumulation of BNCT agents in different intracellular regions, the effect of 10B distribution and geometry factor on dose and energy values was investigated. In addition, two different radiation simulation models were used to compare their results. The intracellular behavior of alpha and lithium-7 particles was investigated. As 10B accumulated closer to the cell center, the total dose and energy imparted by per 10B(n,α)7Li reaction to the cell increased for both cell models. Also, the multi cell model was exposed to more dose and energy than the single cell model due to the influence of the surrounding cells. Besides, the simulated system was modeled as realistic as possible to obtain accurate results.