Study of Radiation Detection Properties of a Pixellated CsI Gamma Imaging Module

CsI scintillators are widely used for the detection of gamma rays due to high light yield, high density, reasonable energy resolution, low cost and ease of operation in the field of radiation and medical physics. Alongwith other radiation detectors, it is used for 511 keV gammas emitted due to positron annihilation emitted from radiotracer injected for diagnosis purposes in nuclear medicine. In order to improve the spatial resolution of such gamma imaging systems, pixellated detectors with individual readout are being developed. The segmentation of slab of scintillator affects the detection properties like intrinsic total efficiency, intrinsic peak efficiency, photo-fraction and Compton/peak ratio. The intrinsic total and peak efficiencies become almost double when SDD was increased from 1mm to 10mm. In this study, we present the results regarding the variation of above mentioned properties with source to detector distance for two gamma energies of 511 keV and 662 keV. Also a comparison of properties with those of NaI is also given.