Programs that are staffed by specialists who have expertise in the therapeutic utilization of radiant energy and its modifiers in the study and management of disease. Radiologists principally read x-rays but may also be certified to utilize some nuclear technology which involves the analysis and imaging of radionuclides and radiolabeled substances in vitro and in vivo for diagnosis and the administration of radionuclides and radiolabeled substances for the treatment of disease, especially malignant tumors.