Design of an Accelerator-Based Epithermal Neutron Beam for Boron Neutron Capture Therapy

Abstract

Recent interest in the production of epithermal neutrons for use in boron neutron capture therapy (BNCT) has prompted an investigation into the feasibility of generating such neutrons with a tandem cascade accelerator1,2. Accelerator-produced neutrons in the range of roughly 200–800 keV are generated in a lithium compound target via the 7Li(p,n)7Be nuclear reaction in a tandem cascade accelerator currently under development by Science Research Laboratory, Somerville, MA. Details of the design of the proton accelerator and operating characteristics will be presented elsewhere in these proceedings3. Recognizing that the accelerator-produced neutrons will be too energetic for use in neutron capture therapy, a detailed dosimetric study was undertaken to determine the energy, or range of energies most suitable for NCT. This study was carried out using three-dimensional Monte Carlo transport calculations; results are discussed briefly here. Once the most suitable range of energies for BNCT was determined, it was then possible to design an appropriate moderator assembly to shift the energy of the neutrons down to the therapeutically useful levels. Such an assembly has been designed with the aid of computer simulation; calculations of treatment parameters indicate that the accelerator neutron beam can provide dose rates and advantage depths comparable to currently available reactor beams for neutron capture therapy.