An optimized epithermal BNCT beam design for research reactors

Boron Neutron Capture Therapy (BNCT) beam design needs a special methodology to satisfy the recommended beam parameters required for the proper delivery of treatment doses. In this work, a new design method for a multi-layered spectrum shifter is proposed in order to improve the design process of epithermal BNCT beams for research reactors. The design method is based on two concepts: stepwise spectrum shifting and separation of the design process into two design stages, namely the material selection and the thickness determination. The method has been applied to two case studies using two different sources: a Watt fission neutron spectrum and neutron-gamma spectra of a typical MTR-type reactor radial beam. The different beam components have been designed with a special focus on the spectrum shifter. Java-based Nuclear Information Software (JANIS) has been used for cross sections computations needed for the selection of the spectrum shifter materials. Monte Carlo N-Particle code “MCNP5” has been used for the beam design. To validate the proposed spectrum shifter design method, comparisons have been done between the proposed spectrum shifter and the known patented material “FLUENTAL™” for both cases. The results of comparisons confirm that the proposed design outperforms the “FLUENTAL™” material. The proposed method proved to be time-saving, simple and efficient. Above all, it is based on a more systematic approach rather than the commonly used approaches. Thus, this method can be applied for other epithermal beams as well as other BNCT facilities such as accelerator-based BNCT facilities.