ACCELERATOR PRODUCTION OF EPITHERMAL NEUTRONS FOR BNCT

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The goal of the Phase II program is to construct and test an accelerator based neutron irradiation facility for boron neutron capture therapy (BNCT). In Phase I, the use of neutron beams producted by the 7Li(p,n)7Be reaction for BNCT was investigated. The result of Monte-Carlo simulations of neutron and photon transport in moderators and a brain-equivalent phantom were used to design an optimized neutron irradiation port. These calculations demonstrated that a moderated accelerator-produced neutron beam is competitive with the best currently available reactor-produced beams with regard to dose-depth distribution, dose rate and dose composition. The neutron flux produced by a 4 mA, 2.5 MeV proton beam on Li can deliver a therapeutic dose to a tumor at the midline of the brain in less than one hour. The accelerator neutron source is based on a new electrostatic accelerator technology currently being developed at Science Research Laboratory. The salient features of the Tandem Cascade Accelerator (TCA) are compactness, low power consumption and the ability to deliver multi-milliampere proton currents at energies up to several million electron volts. The size, capital and operating costs, and facility requirements for this accelerator are compatible with installation in a research laboratory or hospital. The design of a TCA and lithium target capable of producing the high neutron intensities required for BNCT was completed in Phase I. In Phase II, the accelerator source will be fabricated, characterized and used in neutron dosimetry experiments. It is anticipated that this system will provide a versatile, dedicated neutron source for BNCT research.