Nuclear medicine is a branch of radiology that uses radioactive materials, or radiopharmaceutical, to diagnose disease or support differential diagnosis, to monitor disease, and to treat disease. The benefit of nuclear medicine is that it allows close examination of the organs and how they function, down to the molecular level, and allows early diagnosis of disease.

Nuclear imaging begins with the administration of a radioactive substance (radiopharmaceutical or radioactive tracer) through injection, mouth, or inhalation. The right type of radioactive substance must be used for the organ being examined. The radioactive substance will enter the body and collect at the site of the disease or the organ being examined and will give off radiation. This radiation cannot be seen without proper equipment. Radiation will show both the normal and abnormal locations in the body. A special imaging device is used that captures radiation, records it as light symbols, and creates  images of the different parts of the body through the calculations of the computer. The radiologist can then interpret these images.