tomography positron emission tomography (PET) 2010-08-05T02:27:10Z Detection of gamma rays emitted from tissues after administration of natural biochemical substance into which positron emitting isotopes have been incorporated. The paths of the gamma rays resulting from collision of positrons and electrons are interpreted by a computer to form a representation of local concentrations of the isotope-containing substance. MMO:0000129 PET scan measurement_method_ontology mshimoyama