DETECTOR EFFICIENCY AND COMPTON SCATTER IN FULLY 3D PET

Variations in detector efficiency induce significant artifacts in reco nstructed images unless accurate normalization methods are used. Scatt ered events are detected with significantly different efficiencies tha n unscattered events because the photons in scattered coincidences arr ive at the detector at lower energies and over a wide range of angles of incidence. Current methods work well for septa-extended imaging bec ause the scatter fractions are low. The large scatter fractions encoun tered in fully 3D imaging, however, require that these differences be accounted for. We propose a normalization technique that accounts for them and show that it yields more uniform images than two other potent ial methods.