positron emission tomography scan is called a PET scan. A PET scan is used in cancer treatment. It can be done with a CT scan. That's why doctors call it a PET/CT scan. However, people often just call it a PET scan.

Using a radioactive high-tech (PET) scanner can help patients with certain types of cancer avoid unnecessary, non-curable surgery. This new imaging method, although expensive, can "see" cancer much better than a conventional CT scan.