The Estimation of the Nonrecuperable Injury Caused by Ionizing Radiation

Exposure of mice to a non-lethal course of x-ray treatment results in a reduction in tolerance of mice to further x-ray treatment. The reduction in tolerance to x ray amounts to a decrease of the acute LD/sub 50/ by an average of 9.6% of the total amount of the non-lethal radiation previously given. The time of death after the LD/sub 50/ test and the slope of the dose-response curve are not changed by the non-lethal radiation previously given, and it is iaferred from this that the mechanism of acute death and the distribution of radiation sensitivity are not changed. The injury found does not account for the observed mortality of animals from chronically imposed radiation. (auth)