76 N-7 The whole-body counter measures the quantity and the energy of the gamma ray photons that have been emitted by cesium-137, or other In principle, the radionuclides, and that escape from the body. machine is calibrated by measuring the escape of gamma rays from a phantom which has been loaded with the radionuclides in question. Obviously, the whole-body counter comes closest to giving a direct measurement of the body-burden. The collected data obtained with it are presented in Tables N.7, #l, #2, and #3. . or In the case of radionuclides that emit beta rays (strontium-90 alpha particles (transuranics), whose range in tissue before absorption may be at most a centimeter or so down to some micrometers, another method must be used. Recourse is had to The body measuring the daily radionuclide excretion in the urine. content is then calculated from knowledge of the metabolism of the radionuclide in question. This method is not as reliable as whole-body counting. Fortunately in the present case, the detection of strontium and the transuranic elements is not as important as the detection of cesium. The dose can also be calculated from the diet. The primary obstacle here is that the diet is very difficult to ascertain accurately, and in addition more assumptions must be made regarding the metabolism of the radionuclide than would be the case above. The Livermore results are based on this method. Conversely, knowing the daily urinary output of a radionuclide, it is possible to calculate the daily intake by ingestion. For example, based on the work of Jones et al (1985), Skrable et al (1987) and Moss (1988), Dr. E. T. Lessard of the Brookhaven Laboratory has calculated the factors for plutonium-239 given in Table N.4 # 4. Uhen the daily intake is multiplied by the factor, the urinary output is obtained. Conversely, when the urinary output is known, dividing it by the factor will predict the daily intake. The dories and Moss alternatives are offered; at 20-30 years on a constant diet, they differ by a factor of 1.75. I used the Moss-based factor for the calculations used in the text, Section 4.3, because it corrects for earlier errors in the data base which Jones did not know about. (Cont.)