Degradation of spatial resolution in gamma cameras employing sodium iodide or germanium detectors

Abstract

Using Monte Carlo methods gamma -ray scattering in the detector has been studied in relation to its effect on the spatial resolution attainable in gamma cameras. Gamma-ray energies ranging from 0.10 to 0.67 Mev were considered, with crystal thicknesses between 6.3 and 50.8 mm of NaI(Tl) and 5 to 20 mm of germanium. For a monoenergetic gamma -ray, incident along the axis of a cylindrical detector, the distribution of energy depositions occurring in individual interactions in the detector is given as a function of the perpendicular distance from the incident ray to the location of the interaction. The application of pulse height discrimination to various types of gamma camera is discussed.