Introduction
Nuclear medicine began approximately 50 years ago and has evolved into a major medical specialty for both diagnosis and therapy of serious disease. More than 3,900 hospital-based nuclear medicine departments in the United States perform over 10 million nuclear medicine imaging and therapeutic procedures each year. Despite its integral role in patient care, nuclear medicine is still often confused with other imaging procedures, including general radiology, CT, and MRI.

Nuclear medicine studies document organ and function and structure, in contrast to conventional radiology, which creates images based upon anatomy. Many of the nuclear medicine studies can measure the degree of function present in an organ, often times eliminating the need for surgery. Moreover, nuclear medicine procedures often provide important information that allows the physician to detect and treat a disease early in its course when there may be more success. It is nuclear medicine that can best be used to study the function of a damaged heart or restriction of blood flow to parts of the brain. The liver, kidneys, thyroid gland, and many other organs are similarly imaged.