The use of nuclear medicine has increased dramatically over the past two decades but is still used much less frequently than x-rays. It accounts for 12 percent of total radiation exposure.

The radionuclide used in over 75 percent of nuclear medicine procedures is technetium-99m (Tc-99m) because it can be easily obtained, has a convenient half-life of six hours, and it is suitable for incorporating into a wide variety of drugs allowing for examinations of various and specific organs such as the brain, heart, and liver.