An element which gives out radiation.
A type of radioactive substance made up of atoms that disintegrate, emitting electromagnetic radiation.
An isotope (or nuclide) that undergoes radioactive decay.
A radioactive isotope used in a scanning technique of body tissues. Different types of tissue and normal or abnormal tissues absorb varying amounts of the isotopes; these differences are detected, recorded and displayed on a screen.
An atom that disintegrates by emitting electromagnetic rays, known as gamma rays.