The AAPM/RSNA physics tutorial for residents. Physics of PET.

Positron emission tomography (PET) is a coalition of physics, chemistry, physiology, and medicine united in an effort to measure physiologic parameters noninvasively. A PET study consists of producing radiotracers, synthesizing radiopharmaceuticals from the tracers, administering the radiopharmaceutical to a patient, measuring the resulting radioactivity distribution in an organ of interest, and interpreting the activity distribution as a function of physiologic parameters. Radiotracers are produced with medical accelerators that are characterized by the amount of time required to produce a set amount of radiotracer. Radiopharmaceutical production requires automated or remote synthesis modules that are characterized by their efficiency for incorporating the radiotracer into a radiopharmaceutical and the length of time and amount of human interaction required. Imaging protocols must consider sources of image artifacts, the method by which the images will be analyzed, and the uncertainty in the final result. Each of these areas has implications for the cost of the procedure, patient comfort, and the information obtainable from the study. This article gives an overview of these areas and defines the principles that can be used to distinguish between and the consequences of different approaches.