Dosimetric Sunvort to Bpidemicloric and Radiobiolopiec Thyroid Studies Oojectives: Te provide precise dosimetric calculations and measurements to be made in support of radioblologic and epidemiologic studies. Swmerv: Only very tenuous and ccnflicting estimates of internal radiation exposures are~avallable for populations in Utah in the early 1950's. ‘This is due to the Tact that specific measurements for the radioactive iodines were nov routinely made at that time. Therefore, existing data on gross beta and gamma measurements made at that time need to be correlated with concurrent special studies which did involve the measurement of a few animal thyroids ror Llodine, and data trom later tests where both gross beta and gamma and iodine data are available for study. Data from recent experimental work will also be usec. Such data combined with a study of agricultural and dietary factors will be used to construct estimates of total exposures received in the early 1950's by the populations of concern. All the raciobdiclogic studies summarized above necessivate precise careful Fae eochensees autoradiographic, and/or dosimetric measurements and calculations. To dave, very Litvle effort nas been devoted toward reconstructing the cosimevury of the tissues or organs in which tumors ultimately developed among cniléren receiving therapeutic irradiation. The data from the largest roster of such children suggest that irradiation of the pituitary may be an etiologic factor in producing some of the thyroid tumors. <t is of the utmost importance that we try to reconstruct the dosage pavttern of patients exper- jeacing tumors to determine: (1) Whether the primary twnor sites were in a close apposition to or within the direct beam, and (2) Tae importance o? pituitary exposure; (3) Approximate estimates of dosages to tissues of interest.