Radiology: The branch of the health sciences dealing with radioactive substances and radiant energy and with the diagnosis and treatment of disease by means of both ionizing (e.g., x-rays) and nonionizing (e.g., ultrasound) radiation.
Half-life: The time required for the decay of half of a sample of particles of a radionuclide or elementary particle.
Biological half-life: The time required for a living tissue, organ, or organism to eliminate one half of a radioactive substance, which has been introduced into it.
Radiation: Energy transmitted by waves through space or through some medium; usually referring to electromagnetic radiation when used without a modifier
Gamma camera: A scanner that detects the movement of a radiopharmaceutical, emitting gamma radiation during itís movement through the human body.
Radiopharmaceutical: a radioactive pharmaceutical, nuclide, or other chemical used for diagnostic or therapeutic purposes.