Nuclear medicine is a independent specialty with it's own training requirements (two years after an internship) and boards exam, but usually it's run within a radiology department. However, radiology residents get at least six months of training in nuclear medicine and their boards examinations include sections on nuclear medicine. For the majority of nuclear medicine studies, general radiologists do them too. One major exception is therapeutic administration of radioisotopes. Radiologists can also do a one-year fellowship in "nuclear radiology" and get board certified by an ABR CAQ examination, which in that case they can administer therapeutic radionuclides too.