Positron Emission Tomography measures metabolism and detects changes in bodily functions at the molecular level. Computed Tomography produces multiple images of the bone and soft tissue to provide anatomical information. PET/CT superimposes the images to allow the physician to correlate the information from two different exams onto one image. This leads to more accurate diagnosis. PET/CT is used to detect cancer, determine whether cancer has spread in the body, assess treatment, determine reoccurrence, or to confirm cancer free after treatment.