A dosimetric and biological model for neutron capture therapy (NCT) experiments

A hybrid Monte Carlo approach using MCNP in combination with the cell-level code Monte Carlo Damage Simulation (MCDS) is presented to support the design and analysis of experiments for the evaluation of gadolinium (Gd) based agents in neutron capture therapy (NCT). Monoenergetic neutrons (0.025 eV-15 MeV) and polyenergetic neutron beams from NEUTRA, ICON (PSI, Switzerland), and HK1 (LVR-15, Czech Republic) were used to estimate the relative biological effectiveness (RBE) of NCT for the biologically critical endpoint of DNA double strand break (DSB) production relative to ⁶⁰Co γ-rays. Moreover, microdosimetric spectra of protons, electrons, alpha particles and heavy recoils were determined for the aforementioned neutron beams, to enhance the interpretation of energy deposition in subcellular structrures. The proposed, hybrid model and methodology builds on well-validated dosimetry and biophysical models at different spatial scales to create a versatile and generalized framework to estimate dosimetric parameters and RBE. This approach facilitates comparisons between NCT and low linear energy transfer (LET) radiation alternatives.