[Fractionated irradiation of Ehrlich carcinoma using fast neutrons].

Ehrlich's carcinoma growth inhibition was studied under the conditions of fractionated irradiation with fast neutrons and x-rays. Fast neutrons were obtained from a reaction of 13.6 MeV alpha----Be on the Y-120 cyclotron. Neutron beam irradiation doses were within 2-17 Gy, x-ray doses from 7.5 to 72 Gy. Tumors were subjected to local irradiation with 1-8 fractions at a 3-4 day interval. The results showed that an increase in the total duration of a course of irradiation and a decrease in a dose per fraction resulted in a reduced effect of carcinoma growth inhibition. At the same time, an increase in the fast neutron RBE under these conditions from 3.4 (in single irradiation) to 5.4 (in 8-fold irradiation) indicated more pronounced inhibition of reparation and/or repopulation in a tumor in neutron beam irradiation.