Neutron field for boron neutron capture therapy

Recently, the development of an epithermal neutron source has been required by medical doctors for deeper neutron penetrations, which is to be used for deep tumor treatment and diagnosis of metastasis. Several attempts have already been made to realize an epithermal neutron field, such as the undermoderated neutron beam, the filtered neutron beam, and the use of a fission plate. At present, these facilities can not be used for actual therapy. For the treatment of deep tumor, another method has been also proposed in normal water in the body is replaced by heavy water to attain a deeper neutron penetration. At Kyoto University's Research Reactor Institute, almost all physics problems have been settled relative to thermal neutron capture therapy that has been used for treating brain tumors and for biological experiments on malignant melanoma. Very recently feasibility studies to use heavy water have been started both theoretically and experimentally. The calculation shows the deeper penetration of neutrons as expected. Two kinds of experiments were done by using the KUR guide tube: 1. Thermal neutron penetration measurement. 2. Heavy water uptake in vitro sample. In addition to the above experiment using heavy water, the development of a new epithermal neutron source using a large fission plate is in progress, which is part of a mockup experiment of an atomic bomb field newly estimated