A radioactive element used in radionuclide scanning.
n. an isotope of the artificial radioactive element technetium. It emits gamma radiation only, with no beta particles, at a convenient energy for detection by a *gamma camera and has a short half-life. For these reasons it is widely used in nuclear medicine as a *tracer for the examination of many organs (see scintigram). Symbol: Tc-99m.... technetium-99m