» ~ will not be known precisely. | ~4~ The dosimetry device, records the dose or dose rate, which may not reflect accuretely, because of shielding and energy dependence of the device, the deposition of radiant energy at the site of interest, namely the bone marrow and the lining of the intestinal tract. The problems associated with predicting medical effects from physical estination of dose can be further illustrated ac follows: it is apparent that dose estimates available will be air doses. The dese received by the air is of acadenic interest only, since the degree of effect in living things is due to the deposition of energy and its distribution in the critical tissues. Accordingly one must know the depth doce pattern or more precisely the pattern of absorbed jose in sensitive critical tissues. This problen has beer explored experimentally at great length and ‘s described in deteil in references (17). More need not be said here other than the fact that the uniform field of radiation coming at an individual from all directions is more effective per r in air than dose of radiation of directional quality. In urban areas there may te shielding from the fallout field by buildings or inhomogeneities in the field due to drift in dry windy areas, With the prompt radiation shielding may be significant and the proximity of large buildings may ser jfously influence scatter and perturb the uniformity of the radiation. Lastly a fallout field may be made unidirectional by heavy shielding from buildings on one side, Thus estimates of dose calculated from dose rates or derived from an inte- frating type of dosimeter that adds up to the total dose received, or form position of an individual during exposure, cannot be accepted as the best index of the pro- -bable fate of this individual, or as the final guide to treatment, interested in the individual from the The physician is standpoint of sorting casualties with sone chance of survival and those for whom nothing can be done, and of equal importance the troop commander is interested in the over all prognosis of large grows of individuals in order to make plans for disposition end replacement. These two aifferent desires cannot be completely net by physical estimates of dose. ever, nature has been helpful. How. The manifeststions of radistion injury vary with DOE ARCHIVES 3