Quality tests
for
3D
Positron
Emission
Tomography
(PET)
 Images

Positron Emission Tomography (PET) is a technique used in clinical medicine and biomedical (preclinical) research to create images that show how certain organs perform their physiological function (España 2009). Radioactive nuclei are introduced into the patient to label tracer molecules that probe physiological processes. These radioactive nuclei emit positrons that annihilate with electrons from the tissue. An annihilation event usually results in two gamma photons being emitted at nearly 180 degrees and with an energy of 511 keV each. The gamma photons are detected in coincidence in a detector ring so that two gamma photons detected in coincidence define a line of response (LOR) along which the positron annihilation took place. The information recorded in every possible LOR is assembled and, with the aid of image processing tools, it is employed to produce an image of the activity and thereby of the functionality of the organism. Since the first PET scanner was developed in the 1970s, positron emission tomography has been established in oncology, cardiology and neurology. The extension of this technique to preclinical research has represented a great challenge in the last decade, during which very high resolution PET scanners for laboratory animals such as mice and rat