What happens during a PET scan?
Positron emission tomography ( PET) scans are used to see metabolic activity in the tissue of the body. To do this, multiple images of the body or part of the body are created to show the scanned area layer by layer in thin "slices." The computer uses these slices to make a three-dimensional (3D) image.
A weakly radioactive substance called a tracer is used to allow doctors to see the metabolic processes. The tracer is typically injected into the body. It is used at a dose that is considered safe for humans. "Radioactive" means that the chemical substance decays (breaks down) on its own and gives off radiation (energy). By measuring this radiation, the PET scanner can follow exactly where the substance moves inside the body.