Formation of the neutron flux spectrum for boron neutron capture therapy

Boron Neutron Capture Therapy (BNCT) is a promising radiation treatment modality based on the selective accumulation of boron-containing compounds in tumor cells followed by irradiation with a neutron beam. The therapeutic effectiveness of BNCT strongly depends on the characteristics of the neutron flux spectrum, including neutron energy distribution, flux intensity, and the ratio of thermal, epithermal, and fast neutron components. The formation and optimization of an appropriate neutron spectrum are therefore essential for achieving an effective therapeutic dose in tumor tissues while minimizing radiation exposure to healthy organs. This article examines the main principles of neutron flux spectrum formation for BNCT and discusses the influence of neutron energy on the physical and radiobiological characteristics of the treatment process. Particular attention is given to neutron moderation, spectral shaping, beam filtration, and optimization of the neutron beam for clinical applications. The study highlights the importance of selecting suitable moderator and filter materials to obtain an epithermal neutron beam with appropriate intensity and low contamination by fast neutrons and gamma radiation. The results of the analysis can contribute to the development and optimization of neutron beam shaping systems for improving the safety and therapeutic efficiency of BNCT.