Effect of Dose Size on Rate of Recovery from Radiation Damage in Mice

Abstract

Latent residual injury contributing to the acute lethal response in RF/J mice 80 to 120 days old after X-ray doses of 100 to 650 r was estimated 2 days after exposure by determining the additional dose required to produce 50% mortality in 30 days. The fraction of latent damage repaired, as measured by this technique, decreased progressively with increasing dose. On the assumption that the recovery pattern can be described by a simple exponential equation, recovery rate constants for the various doses were estimated. It was concluded that the recovery rate decreased inversely with the square of the dose, and it was suggested that equations using recovery rate constants should be modified accordingly. When repair was expressed in terms of "roentgens of latent damage repaired," it appeared that a maximum rate of repair occurred at a dose of 300 r. Higher doses severely depressed the repair mechanism.