SIMULATION OF IMAGING WITH SODIUM-IODIDE CRYSTALS AND POSITION-SENSITIVE PHOTOMULTIPLIER TUBES

The imaging characteristics of miniature gamma cameras that consist of a single sodium iodide (NaI(Tl)) crystal coupled to a position-sensit ive photomultiplier tube (PSPMT) have been studied via Monte Carlo sim ulations. Images obtained with such cameras with the use of convention al position calculations exhibit considerable distortions, particularl y compression. This study demonstrates that the distortions result pri marily from non-uniform sensitivities of PSPMTs and secondarily from n on-linear responses of PSPMTs, light-reflection properties resulting f rom the treatments of crystals, and light-refractive properties of gla ss interfaces between crystals and photocathodes. Simulation results a re compared to images obtained with a prototype miniature gamma camera .