Technical Principle of PET (Positron emission tomography)
Positron emission tomography Positron emission tomography is an imaging modality for obtaining in vivo cross-sectional images of positron-emitting isotopes that demonstrate biological function, physiology, or pathology. In this technique, a chemical compound with the desired biological activity is labeled with a radioactive isotope that decays by emitting a positron or positive electrons. The emitted positron almost immediately combines with an electron and the two are mutually annihilated with the emission of two gamma rays. The two gamma-ray photons travel in almost opposite directions, penetrate the surrounding tissue, and are recorded outside the subject by a circular array of detectors. A mathematical algorithm applied by the computer rapidly reconstructs the spatial distribution of the radioactivity within the subject for a selected plane and displays the resulting image on the monitor. Thus, PET provides a non-invasive regiona...