Regionally Fractionated X-Irradiation Equivalent in Dose to Total-Body Exposure

Abstract

Mortality following exposure of the entire body to acutely lethal doses of X-radiation was considerably reduced in mice, and to a lesser degree in rats, by irradiating the abdomen shortly before, or after, the remainder of the body. An appreciable decrease in radiation mortality was also obtained in mice by shielding the exteriorized spleen during exposure, even though the spleen alone had been irradiated with the same dose prior to exposure of the body. The time intervals allowed between exposures in these expts. ranged from 10 min. to 4 hrs. Possible explanations for these findings are discussed in the light of current concepts regarding recovery from radiation injury, and it is suggested that the results may be indicative of the action of a "recovery factor" (or factors) emanating from the body region shielded during the first irradiation in each instance.