ABSTRACT
The histopathologic effects of radiation from internally deposited radionuclides are essentially similar qualitatively to those produced by radiations from external sources, although sufficient amounts of certain nuclides may also exert chemical influences upon cells and tissues. The more generalized the distribution the more the pathology resembles that seen following whole-body irradiation from external sources. The individual and essential effects of radiations from internally deposited radioactive isotopes themselves are qualitatively similar to those caused by radiations from external sources. The carcinogenic effects of internally deposited radioisoptes are determined by the localization of the absorbed radiation and energy and the relative susceptibility of the irradiated tissues for induction of neoplastic response. Radioactive isotopes, with their nonuniform irradiation of lung tissue, including regions of high dose, appear to be more carcinogenic in lung than radiation from external sources. Some radioactive isotopes, for example tritium or sodium, upon deposition in blood, become widely and diffusely deposited throughout the body tissues.
