Influence of dose rate on carcinogenesis resulting from x-ray, 113In, and 198Au irradiation.

The potential hazards from internally administered radionuclides used in nuclear medicine are usually compared with one another and with diagnostic x-rays on the basis of the absorbed dose in rads, with no regard to the dose rate of the radiation. This study compared the carcinogenic potential of a dose of 250 rads delivered at different dose rates to rat livers by x-ray, 113mIn, and 198Au. The chemical carcinogen N-2-fluorenyldiacetamide was administered after irradiation to reduce the latent period and increase the number of radiogenic liver tumors. No significant difference in tumor incidence was observed among groups of animals treated with either 198Au, 113mIn, or x-irradiation.