A single coned Poly-Biz moderator designed for animal irradiation in boron neutron capture therapy.

BNCT is considered to be a promising method for the treatment of malignant tumors, which ensures the selective destruction of malignant tumor cells by accumulating non-radioactive atomic boron-10 nuclei in them and subsequent irradiation with neutrons. As a result of the absorption of a neutron by boron, a nuclear reaction occurs with the release of energy in a cell containing boron, which leads to its death. To date, two drugs for targeted delivery of boron, boronophenylalanine and sodium borocaptate, have been developed, which ensures selective accumulation of boron in a number of tumors, and a number of charged particle accelerators with neutron-generating targets and with neutron beam shaping assemblies have been developed providing the quality of the neutron beam required for therapy. The paper presents a critical analysis of the methods used to form a therapeutic neutron beam and proposes a new concept of a neutron beam shaping assembly, supported by the results of numerical simulation validated by in-phantom measurements.

Neutron Source Based on Vacuum Insulated Tandem Accelerator and Lithium Target.

A compact accelerator-based neutron source has been proposed and created at the Budker Institute of Nuclear Physics in Novosibirsk, Russia. An original design tandem accelerator is used to provide a proton beam. The proton beam energy can be varied within a range of 0.6-2.3 MeV, keeping a high-energy stability of 0.1%. The beam current can also be varied in a wide range (from 0.3 mA to 10 mA) with high current stability (0.4%). In the device, neutron flux is generated as a result of the 7Li(p,n)7Be threshold reaction. A beam-shaping assembly is applied to convert this flux into a beam of epithermal neutrons with characteristics suitable for BNCT. A lot of scientific research has been carried out at the facility, including the study of blistering and its effect on the neutron yield. The BNCT technique is being tested in in vitro and in vivo studies, and the methods of dosimetry are being developed. It is planned to certify the neutron source next year and conduct clinical trials on it. The neutron source served as a prototype for a facility created for a clinic in Xiamen (China).