Nuclear medicine uses radionuclides to image various organs and perform functional tests. Certain radionuclides can also be used for therapeutic purposes.
In diagnostics, the artificially produced radionuclide Technetium-99m (Tc-99m) is used most often. It has a half-life of about 6 hours, so it is very short-lived, and is generally injected intravenously. Only a very small amount of the radionuclide is needed, so the radiation load is very low. There are really none of the typical side effects of contrast agents due to the very low doses in nuclear medicine. The radionuclide is bound to special carriers, depending on the issue, so that individual organ systems and their functions can be targeted for the examination.
The radiation emitted by the radio nuclide is captured by a special camera (gamma camera), which converts this radiation into electrical impulses and uses them to produce an image (scintigram) or obtains functional data using a computer system (functional scintigraphy.) In the latter case, conclusions can be drawn about the function of an organ (e.g., kidney function.)