Radionuclide Scan
A radionuclide scan uses radioactive material that emits gamma rays, called a tracer, which is administered either orally or via injection.
Many different radionuclide tracers are available to radiologists, each of which concentrates in a different organ or part of the body. For example, radioactive iodine is generally used in order to scan a patient's thyroid gland; on the other hand, cobalt may be employed to scan the liver. Healthy cells in a given organ or body absorb substantially more of the tracer than less active or potentially damaged cells.
Technicians use a special gamma-ray camera, known as a "scintillation camera" or radionuclide scanner, in order to detect the gamma rays emitted from tracers within the patient's cells. This data is then uploaded to a computer, which produces an image displaying the distribution of gamma rays in the area being diagnosed. Active, healthy cells appear as "hot spots," while inactive, diseased cells show up as "cold spots," having not absorbed as much of the tracer material.
A radionuclide scan can take anywhere from twenty minutes to several hours depending on what is being scanned. Although the procedure is virtually painless, the patient must lie quite still. In order to flush out the radiation afterwards, the physician may have the patient drink large amounts of water after the procedure. The radiation doses are quite low and pose no real threat to the patient; however, it can damage a fetus, so pregnant and nursing women must avoid a radionuclide scan.
The radionuclide scan is also known as an isotope scan.
Sources
CancerWeb. "Radionuclide Scan." http://cancerweb.ncl.ac.uk
MedicineNet.com. "Definition of Radionuclide Scan." http://www.medterms.com
Patient UK. "Radionuclide (Isotope) Scan." http://www.patient.co.uk