Boron Neutron Capture Therapy is a two component modality. It is based on selective delivery of a boronated pharmaceutical to cancerous tissue, followed by irradiation with thermal neutrons and subsequent capture by the boron nuclei. A collaborative effort will be undertaken to develop a neutron gun capable of delivering a filtered, focused beam of thermal neutrons. This will provide a local treatment modality which is extremely dose-sparing to healthy tissue. The neutron gun is based on the use of a new technology, capillary neutron optics, which has recently demonstrated significant flux enhancements for cold neutrons. Modeling based on experimental measurements of capillary optics will be used to determine the feasibility of the device when paired with a variety of accelerator or reactor based neutron sources. The project team includes experts in neutron optics, neutron sources, moderator design and modeling, and boron neutron capture therapy. The neutron gun will be of particular benefit for intraoperative treatment of the surgical bed following gross total resection of tumors such as skin, breast, sarcoma and metastatic lesions, which typically require a local dose boost with conventional radiation treatment. The neutron delivery system will also be advantageous for intraoperative treatment after exposure of ocular melanoma.