It is possible to have lung cancer after having a positron emission tomography scan, and a PET scan is one test used for diagnosis of cancer, states MedlinePlus. A PET scan is used to show how organs and tissues are functioning.
A PET scan uses a radioactive substance known as a tracer in the bloodstream, according to Cleveland Clinic. The tracer is detected by the machine performing the scan, and the data is used to create a 3-D image of the body area being scanned.
PET scan uses include cancer diagnosis, determining how far a cancer has spread or evaluating the progress of cancer treatment, explains MedlinePlus.