An Epithermal Neutron Source for Cancer Therapy

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DESCRIPTION (provided by applicant): We propose to develop a commercial neutron source for the treatment of brain and liver cancer based on boron neutron capture therapy (BNCT). Boron-containing compounds are injected into a patient's bloodstream and accumulate in a malignant tumor. When irradiated with neutrons, the boron atoms preferentially capture neutrons and decay, releasing short-range radiation that kills the tumor but does not appreciably damage other tissues. BNCT has been tested using primarily nuclear reactors that are large and expensive and cannot be used in a clinical setting. The proposed source is relatively inexpensive, compact enough to be used in hospitals and promises safe operation. In addition, it will be designed to produce an ideal epithermal neutron spectrum (unlike reactors) and is expected to produce enough neutron flux for short treatment times. The proposed source consists of an rf-plasma fast-neutron source using the D-T reaction and an optimized, compact moderator to slow and collimate the neutrons. These components are brought together in a novel fashion to produce a high-flux, optimum epithermal neutron spectrum for BNCT. Tritium storage, replenishing and recycling will be achieved by a self-contained vacuum system to minimize radiation and explosion hazards. Our design is novel in that it integrates the plasma neutron source using an optimized fast-neutron target with new moderator materials and geometries for greater efficiency and compactness. Preliminary analysis shows that optimizing the target-anode's geometry can decrease the required power to the generator when integrated with a properly designed moderator. This Monte-Carlo N-particle (MCNP) analysis will be improved to determine the D-T generator's geometry with a moderator configuration that will produce a neutron beam of optimum neutron energy and minimize power consumption. To facilitate water cooling, the ion beam power density on the target anode will be less than 150 Watts per square cm. We will create a source model for dose calculations using the Simulation Environment for Radiotherapy Application (SERA) treatment program. For comparison, we will calculate the dose in a patient model with the MCNP program. The fast-neutron generator will be designed using computer codes developed at the research institute. Prior fast neutron sources have been fabricated and tested demonstrating the efficacy of these codes and the research institute's technological skill.