There are many types of nuclear medicine scans, which use radioactive decay as a diagnostic and treatment tool. The scans require radioactive tracers to measure the health of different bodily systems, such as liver and thyroid function. After a tracer is injected or ingested by the patient, scanning devices measure the tracer's progress throughout the body. Irregularities in the distribution of the radioisotope are registered by the scan and can indicate a serious medical condition, such as cancer. Some nuclear medicine scans incorporate other medical imagining technology to produce more accurate results.

Nuclear medicine scans are a branch of medical imaging. Their purpose is to measure the real-time function of bodily systems, including the gallbladder, heart, lungs and thyroid. Before a scan, a physician injects a patient with or has a patient ingest a solution containing a safe radioactive isotope that targets the bodily system being tested. A patient remains motionless for a period of minutes or hours while a scanning device measures how the body processes the radioactive isotope.

One of the many types of nuclear medicine scans is cholescintigraphy, also known as the HIDA (hepatobiliary iminodiacetic acid) scan. In a healthy patient, the radioactive isotope travels through the liver and into the gallbladder within one hour of injection. If the isotope does not appear in the gallbladder, it indicates a duct obstruction between the liver and gallbladder. Due to advances in ultrasound technology, the number of HIDA scan procedures performed in developed countries is falling.

Nuclear medicine scans also detect the presence of glandular dysfunctions, one such example being hyperthyroidism. To test for this disorder, a patient ingests a pill containing a small amount of radioactive iodine and returns for testing several hours later. Instead of lying down for an hour or more, a technician simply places a sensor plate against the neck for four minutes. The plate records the amount of radioactive iodine the thyroid has absorbed since ingestion. Above normal levels indicate hyperthyroidism.

Other nuclear medicine scans are a key tool in diagnosing different types of cancer. For example, combining nuclear medicine scans with traditional full body scans such as MRI or PET scans are common method of discovering tumors. Having a full body image rather than just portions of the body scanned through nuclear medicine provides a level of detail that only exploratory surgery could once provide. The technology used for these dual scans is especially valuable in checking for the growth of new tumors in patients whose cancer has gone into remission.