nuclear medicine, a medical discipline that uses radiation emitted by radioactive isotopes in the diagnosis and treatment of disease. Forms of radiation important in nuclear medicine include alpha and beta particles, gamma rays, and x-rays. Radioactive elements used in nuclear medicine, called radionuclides or radiopharmaceuticals, are produced artificially. Radiopharmaceuticals are used as tracers for assessing the structure, function, secretion, excretion, and volume of a particular organ or tissue. They are also used to analyze biological specimens and to treat specific diseases such as thyroid cancer. An important component of nuclear medicine is imaging, which involves administering radiopharmaceuticals to a patient orally, intravenously, or by inhalation to localize a specific organ or system and its structure and function. Scanning instruments convert the radioactive emissions into an image of the organ or system.
