An accelerator-based neutron irradiation facility for neutron capture therapy is proposed which is based on a 2.5 MeV proton beam bombarding a lithium target. The quality of the neutron beam (in terms of neutron energy spectrum and gamma ray contamination) generated by the proposed facility design has been demonstrated previously to be suitable for treating deep-seated tumors. However, to accomplish neutron capture therapy during reasonable treatment periods (approximately 1 hour) requires a beam current of about 30 mA of 2.5 MeV protons. This beam current translates to a heating rate of 75 kW at a heat flux in excess of 1000 watts/cm2. Many of the building blocks for the proposed neutron irradiation facility have already been developed and demonstrated including the radiofrequency quadrapole proton accelerator and the moderator system. A key building block heretofore unavailable is the focus of this proposed Phase I study, viz, the target and associated target cooling system. The scope of the proposed study will focus on the analysis and design leading to the assessment of the technical and economic feasibility of the proposed irradiation facility with particular emphasis on the target and associated cooling system. This program will include preparation of drawings/specifications in preparation for construction of the neutron irradiation facility during Phase II.
