Nuclear Medicine
Nuclear medicine involves the use of small amounts of radioactive materials (or tracers) to help diagnose and treat a variety of diseases. Nuclear medicine determines the cause of the medical problem based on both the function and structure of the body part being examined. 
What Is Nuclear Medicine?
Nuclear medicine is a specialized form of diagnostic imaging. Patients are given a radioactive substance either by mouth or intravenously that collects in specific body organs. The gamma camera is a large cylindrical piece of equipment which detects energy being emitted from the organ of interest by the radioactive substance which has localized there. It is positioned near the skin surface overlying the body part being examined. Both images and physiologic data can be produced by computer processing of the pattern of detected energy.
Nuclear Medicine scans are typically painless and patients are exposed to no more radiation than in a common X-ray.
Images from nuclear medicine scans can assist the physician in diagnosing many conditions and diseases. Assessing organ structure and function can help physicians to detect infections, tumors, and other disorders.
How Should I Prepare for this Procedure?
Typically there is no special preparation for a nuclear medicine test. However, your physician may ask that you miss a meal before your test if your procedure requires imaging of the stomach or gallbladder. Also, you may be directed to drink plenty of water for tests of the bones and kidneys.