INFLUENCE OF PHANTOM SIZE, SHAPE, AND DENSITY, AND COLLIMATOR SELECTION ON THE DUAL PHOTOPEAK WINDOW SCATTER CORRECTION METHOD

Results from a Monte Carlo investigation are presented for the applica tion of the dual photopeak window (DPW) scatter correction method to p hantom geometries of varying shapes, sizes, and densities as well as t o several collimators. A Monte Carlo program was used to simulate a Tc -99m point source at locations of 0.5 cm from the phantom surface, at the center, 0.5 cm from the bottom, and 4/5 the distance lateral from the center for each case of variation. DPW was then used to correct fo r scatter using a regression relation determined for a 30.5 cm x 23.0 cm water-filled elliptical tub phantom using an ultrahigh resolution c ollimator. The application of DPW in all cases accounted for an approx imate twelve-fold reduction in scatter fraction with an excellent agre ement between the true scatter and scatter estimate distributions both at the tails and under the peak of the point spread functions.