Fluorodeoxyglucose is injected into the patient’s bloodstream. It accumulates in body tissues with a high energy demand, especially tumours. FBD moves from the blood vessels into surrounding tumour cells. The fluorine-18 atom decays within the tumour cells, emitting a positron.These radioisopes are short-lived(half-lives on the order of seconds or minutes). Carbon, oxygen and nitrogen are key elements in biological systems and have significant physiological potential as they can replace atoms in molecules that are necessary for metabolism. The low-molecular-weight radioisotopes are produced by charged particle bombardment and typically, produced in a cyclotron. All clinical applications of PET have employed 18FDG(18F-labeled fluorodeoxyglucose).