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

Abstract

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 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 neutrons/second per milliampere of electron current is shown obtainable. Additionally, the neutron beam is modified and characterized, employing two unique moderating materials (an composite and a stacked Al/Teflon design).