special subjects
Positron Emission Tomography (PET)
Disadvantages of PET
The amount of radiation exposure from PET is similar to that from CT. When PET and CT are done during a single examination, the radiation dose is significantly increased. Because radionuclides used in PET give off radiation for only a short time, PET can be done only if the radionuclide is produced at a nearby location and can be obtained quickly. PET is relatively expensive and not widely available. 