Study of Highly Pixelated CdZnTe Detector for PET Applications

We are investigating the feasibility of a high-resolution PET insert device based on a Cadmium Zinc Telluride (CdZnTe) detector with 350 μm anode pixel pitch to be integrated into a conventional animal PET scanner to improve its image resolution to sub-500 micrometer range. In this work, we have used a simplified version of the future 2048-pixel CdZnTe planar detector with 250 μm anode pixel size and 100 μm gap. This simplified 9 anode pixel structure makes it possible to conduct experiments without a complete ASIC readout system (with 2048 channels) that is still under development. We characterized this CdZnTe detector by investigating it charge sharing, spatial resolution, and energy resolution. We imaged a Na-22 point source using the coincidence events between this 350 μm pixelated CdZnTe detector and a lutetium oxyorthosilicate (LSO) based Siemens Inveon PET detector. The reconstructed PET image shows a resolution of 590 μm full width at half maximum (FWHM) by using single-pixel events. When we included double-pixel charge sharing events in the image reconstruction, the image resolution was degraded to 655 μm, but the sensitivity of the coincidence system increased 2.5 to 3 times.