PET/CT is a medical imaging technique that combines two different technologies: positron emission tomography (PET) and computed tomography (CT). PET imaging uses a radioactive tracer to detect changes in cellular activity, while CT imaging provides anatomical information about the body. The history of PET/CT dates back to the 1970s when PET imaging was first developed. In the early 2000s,the integration of PET and CT scanners led to the creation of PET/CT imaging, which has since revolutionized clinical practice. The modality involves the injection of a radioactive tracer, which emits positrons that interact with nearby electrons, producing gamma rays that are detected by the PET scanner. The CT component uses X-rays to produce detailed images of the body's anatomy. The PET and CT images are then combined to provide a comprehensive view of cellular activity and anatomical structure.