PET works by injecting a small amount of radioactive tracer into the bloodstream. The most commonly used tracer in oncology is Fluorodeoxyglucose (FDG), a glucose analog. Cancer cells, being highly metabolically active, absorb more FDG than normal cells. The tracer emits positrons as it decays, which then collide with electrons, producing gamma rays. These gamma rays are detected by the PET scanner, which constructs detailed images showing areas of high metabolic activity.
