Recovery and Repopulation in Mouse Skin after Irradiation with Cyclotron Neutrons as Compared with 250-Kv X-Rays or 15-Mev Electrons

Abstract

Skin reactions on the legs of mice irradiated by cyclotron neutrons, 15-Mev electrons, or 250-kv X-rays have been compared. The reactions in groups of 6 mice each exposed to a given dose were scored on an arbitrary scale, and the average daily reaction was plotted against time. For equal maximum reactions, no difference was found in the rates of increase and subsequent decrease of skin reactions after neutron, electron, or X-irradiation. This finding is interpreted as showing that rates of cellular repopulation are not significantly different after the high-LET [linear energy transfer] or low-LET irradiation. The magnitude of the short-term recovery in mouse skin, as measured by split-dose irradiations given 24 hrs apart, was found after fast neutrons to be 1/2 to 2/3 as great as that after X-rays or electrons, when allowance was made for the single-dose RBE [Relative Biological Effectiveness].