Nuclear medicine is a branch of medicine that uses radioactive materials (radiopharmaceuticals) to diagnose and treat disease. Nuclear medicine is unique because it gives doctors information about both structure and function. Nuclear medicine examinations can often identify abnormalities very early in the progression of a disease.

Nuclear medicine scans are safe and painless. Small amounts of radiopharmaceuticals are introduced into the body by injection, swallowing, or inhalation. Radiopharmaceuticals are attracted to specific organs, bones, or tissues. A typical nuclear medicine scan requires very little radiation exposure, comparable to that of an x-ray. A special camera (PET, SPECT, or gamma camera) is then used to image the distribution of radiopharmaceutical in the body.

Common applications include PET scans for cancer, thyroid scans for diagnosis and treatment of hyperthyroidism, cardiac stress tests for coronary artery disease, bone scans for orthopedic injuries or infection, and liver and gallbladder scans to identify abnormal function or obstruction. In all, there are over 100 tests available.

The emergence of hybrid imaging equipment such as PET/CT and SPECT/CT has significantly enhanced diagnostic accuracy. New radiopharmaceuticals and therapies are in development that target molecular processes. Nuclear medicine and molecular imaging are improving our understanding of a range of diseases and our ability to image them.