A Gamma Camera is a device used to image gamma radiation emitting radioisotopes, a technique known as scintigraphy. The applications of scintigraphy include early drug development and nuclear medical imaging to view and analyse images of the human body of the distribution of medically injected, inhaled, or ingested radionuclides emitting gamma rays. A gamma camera consists of one or more flat crystal planes or, detectors, optically coupled to an array of photomultiplier tubes, the assembly is known as a 'head', mounted on a gantry. The gantry is connected to a computer system that both controls the operation of the camera as well as acquisition and storage of acquired images. The system accumulates events, or counts, of gamma photons that are absorbed by the crystal in the camera. Usually a large flat crystal of sodium iodide with thallium doping in a light-sealed housing is used. The crystal scintillates in response to incident gamma radiation. When a gamma photon leaves the patient, who has been injected with a radioactive pharmaceutical, it knocks an electron loose from an iodine atom in the crystal, and a faint flash of light is produced when the dislocated electron again finds a minimal energy state. The initial phenomenon of the excited electron is similar to the photoelectric effect and particularly with gamma rays the Compton effect. After the flash of light is produced, it is detected. Photomultiplier tubes (PMTs) behind the crystal detect the fluorescent flashes events and a computer sums the counts.