An accelerator-based epithermal photoneutron source for boron neutron capture therapy

Boron neutron capture therapy is an experimental cancer radiotherapy modality in which a boronated pharmaceutical that preferentially accumulates in malignant tissue is administered, followed by exposure of the tissue in the treatment volume to a thermal neutron field. Presently in the US and Europe, for treatment of deeper-seated tumors, an epithermal beam is felt preferable in generating the necessary thermal neutron field. Boronated cells are selectively destroyed via energy deposition resulting from the [formula omitted] interaction. Current usable beams are reactor-based; a viable alternative is production of the epithermal neutron beam using an accelerator. Various proposed accelerator-based designs exist, most based on proton beams with beryllium or lithium targets. This dissertation examines the efficacy of a novel approach incorporating an electron linear accelerator (4 to 8 MeV) in the production of a photoneutron source, which may help to resolve present concerns associated with some accelerator-based sources, including target cooling. A conceptual design to produce epithermal photoneutrons, with high energy bremsstrahlung on deuterium targets, is presented along with computational and experimental neutron production data. A clinically acceptable epithermal neutron flux on the order of [formula omitted] neutrons/second per milliampere of electron current is shown obtainable. Additionally, the neutron beam is modified and characterized, employing two unique moderating materials (an [formula omitted] composite and a stacked Al/Teflon design). © 1997, American Association of Physicists in Medicine. All rights reserved.