iQID (intensified quantum imaging detector) is a novel CCD/CMOS-based ultra-high-resolution photon-counting gamma-ray and x-ray detector technology recently developed at the Center for Gamma-Ray Imaging (CGRI) at the University of Arizona. In this work, we report further advances in iQID's capabilities in terms of dark-noise suppression, sensitivity and field of view (FOV). A new frame-parsing algorithm has been developed that is capable of eliminating certain kinds of dark noise originating in the image intensifier while at the same time maintaining high processing speed for photon-counting applications. To improve detector sensitivity, a thicker 1.65 mm columnar CsI(Tl) scintillator has been tested and compared against the original 450 μm columnar CsI(Tl) scintillator in terms of detector sensitivity and resolution. A study of the depth-of-interaction effects of the thicker scintillator has been performed. Simulation and experimental results are in agreement. Finally, to facilitate the use of iQID technology for clinical applications, four large-magnification fiber-optic tapers were tiled together to increase the total detection area to 188×188 mm2. When all of the upgrades are combined, a novel high-sensitivity, high-resolution and large-FOV CCD/CMOS-based gamma-ray detector prototype will be available for evaluation in preclinical and clinical applications.