Radionuclide imaging is a nuclear medicine technique that allows physicians to obtain clear images of various parts of the body. Tiny amounts of radioactive materials (called “tracers”) are injected into the patient’s body. The tracers emit a type of energy called gamma rays, which are detected by special devices.

For example, PET scans (positron emission tomography) use machines called photomultiplier-scintillator detectors to detect the gamma rays. Bone scans, SPECT scans (single photon emission computed tomography) and thyroid scans use a gamma camera to detect the energy. The information detected and recorded by these machines is then analyzed and reconstructed by computers to create clear images of the target area of the patient’s body

For most people, the tracer is harmless and is flushed from the body after the test. Patients are often encouraged to drink plenty of fluids and urinate frequently to help flush the tracer from the body. For most people, the amount of radiation received during radionuclide imaging is considered minimal and safe.

Radionuclide imaging may detect the source of unexplained pain and a number of conditions, including fractures, arthritis, infections and tumors.