Discrimination among Injury Processes Reflected in Acute Radiation Mortality

Summary

Several modes of injury that contribute to acute radiation lethality may be distinguished in two complementary ways: (1) by pathological examination and (2) by analysis of the kinetics of death after single exposures of varying degrees of protraction. The analytical approach is discussed, and statistical procedures are applied to 30-day mortality in 3–4 day chicks after ⁶⁰Co γ-irradiation for exposure times varying from 3 to 1440 min. Kinetic analysis suggests that two irreversible (time-independent) processes lead to different kinds of injury. Time-dependent effects are taken to reflect reversible injury mechanisms. Three different processes of this kind are distinguished, each characterized by an accumulation of injury during exposure at a rate proportional to dose-rate and a constant (linear) reversal, or reduction, of the radiation effects.