. The basic aspects of radiation effects on living systems. Radiation -- Physiological effect. 454 RADIATION INJURY AND LETHALITY tion, called the cumiilant lethality function, Cl, and tj and ^o are the survival times of the representative exposed and control animals, respec- tively. The Cl for ABC mice is presented in Fig. 7. It shows three distinct branches. The impulse lethality function, Sl, is obtained by differentiating Cl (Fig. 8) and shows two pronounced peaks of phasic injury and a final constant branch. This final branch can be shown - - ^ ^
. The basic aspects of radiation effects on living systems. Radiation -- Physiological effect. 454 RADIATION INJURY AND LETHALITY tion, called the cumiilant lethality function, Cl, and tj and ^o are the survival times of the representative exposed and control animals, respec- tively. The Cl for ABC mice is presented in Fig. 7. It shows three distinct branches. The impulse lethality function, Sl, is obtained by differentiating Cl (Fig. 8) and shows two pronounced peaks of phasic injury and a final constant branch. This final branch can be shown - - ^ ^ 100 150 Time, days 200 250 Fig. 8. Impulse lethality function, Sl, for ABC male mice. Obtained by numerical differentiation of Cl (Fig. 7). The horizontal lines give the mean derivative values estimated between adjacent dose groups, and the continuous curve indicates the nature of the function. The peaks of lethality at 10 and 40 days correspond to ob- served peaks of kiUing by single doses of x-rays. to persist as late as 600 days (data of Lorenz; see Fig. 9). The two peaks of injury at 10 and 40 days correspond to the observed peaks of killing following single massive doses of x-rays. Survival under daily exposure has been studied by several investi- gators for several species. The cumulant lethality functions for these species, wdth correction for normal aging, are shown on logarithmic scales in Fig. 9 (34). We see that the initial rise is nearly identical for all species and has a slope of This initial rise is presumably relatively uninfluenced by recovery, and, since all species appear to be described by a common line, there is a suggestion that their differences in sensi- tivity are due almost entirely to differences in the capacity to recover, which appears in the time order in which they fall away from the branch of unretarded accumulation. Following the plateau appears the final, late branch, which appears to have unit slope and which may be thought. Please note
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