AdBRIONE or o> SE hetae temasine oH v LOS - VS7 KCI 6547 401879 9 Acute Whole Body Radiation Injury: Pathogenesis. Pre- and Postradiation Protection Vicror P. Boxp, M.D., Pu.D., Etaexr P. Crongkire, M.D., AND Ropert A. Conanrp, MLD. ‘False facts are highly injurious to the progress of seience for they often endure long; but false views. if supported by someevidence, dolittle hurm for everyone tukes a salutory pleasure in proving their falseness.’”’ Caries Darwin 9.1 General Notes Exposure of the body to penetrating radiatious produces ionization in the tissues. There is a disagreement as to theinitial biological effect therefrom and the sequence of subsequent effects is not adequately known. At the present time it is not possible to bridge satisfactorily the gaps Letween the effects of radiation on pure chemical systems, the single cell, and the integrated mammal. Accordingly, it can be stated that little is known about the precise mechanisms of the action of ionizing radiation at the mammalian level. On the other hand, effects at the various levels have been studied extensively and certainly the end results in the mammal are well characterized today, Radiation illness in its broad sense can be produeed by all types of ionizing radiation. However, the dose required varies with the kind, the rate of administration and the penetrability of the rays. Furthermore. there may be situations in which the injuries are produced by a combination of different radiations, some of which are highly penetrating and some of which may be absorbed completely by the surface lavers of the body. Much confusion has arisen because of the inadequate means of measuring the response to radiation and the standardization of a physical unit that ix adaptable for all sizes of animals and all types of radiation. The roentgen, or “rr,” a measure of the ionization in air, does not necessarily measure the JG1260 Lal 203