Applications of Monte Carlo technique to boron neutron capture therapy

Today neutron capture therapy (NCT) is a promising form of radiation therapy. It includes two interconnected features - the infusion or delivery of a capture compound, which preferentially concentrates in the tumor, followed by the irradiation of the tumor site with neutrons. As the isotope 10B is often used as the neutron capture agent in the compound, NCT is called boron neutron capture therapy (BNCT). The most suitable neutrons for BNCT are neutrons with energies in region from 1 ev to 20 keV. Such epithermal neutron beams may be formed at nuclear research reactors. The concept of the source consists in transformation of the reactor radiation into epithermal radiation. Modifications of research reactors may be relatively straightforward and not prohibitive cost, especially in comparison with construction of new reactors specialized for BNCT. But any reactor modification should be forestalled the careful calculations which are taking into account all peculiarities of the specific reactor system. Implementation of such calculations demands application of Monte Carlo technique. We give a demonstration of it on the example of calculations of the neutron source at the Kyiv research reactor for the boron neutron capture therapy aims using general Monte-Carlo radiation transport code MCNP4C. (author)