The research of the characteristics of fields of fast neutrons on a beam B-3 of reactor BR-10 and the results of neutron therapy on the affected by cancer tumors

Researches on characteristic of a neutron B-3 beam of the reactor BR-10 and clinical experience in external beam radiation therapy (EBRT) on the cancer tumors are represented. One from the most actual problems in the medical radiology is to improve therapy enhancement factor (TEF). For this purpose various techniques are used: non-standard fractionation of a dose of neutrons, methods of its supply, modifiers of ray effect etc. To the present time 350 patients with various localizations of cancer tumors have been processed by EBRT. A horizontal B-3 beam has a rather wide spectrum with a mean energy of 0.49 MeV and neutron beam density on the patient chair of approximately 3 x 108 n/cm2s at the distance of 10 m from the reactor surface, neutron component being 70 % in the energy region between 0.1 MeV and 4 MeV. The available clinical experience in EBRT allows to change B-3 neutron beam characteristic to improve TEF. Moreover, extensive studies in possible application of a B-3 beam for neutron-capture therapy (NCT) are being conducted now. So it is necessary to perform calculation substantiation of both EBRT and NCT or according to neutron energy. (J.P.N.)