Noise equivalent count study of pixelated CdZnTe detectors

The quality of a nuclear medicine image depends on the sensitivity, the scatter rejection efficiency and on system spatial resolution. The currently used NaI gamma cameras suffer from relatively poor energy resolution, leading to low Compton scatter rejection and low-contrast images. A large effort is currently invested in replacing the current technology with CdZnTe technology. We performed an experimental study revealing the local and global sensitivity and the energy resolution of a CdZnTe monolithic array. A correlation between experimental measurements and a Monte-Carlo simulation, using the noise equivalent count criteria, provided a qualitative comparison between NaI and a future performances of CdZnTe gamma cameras. The effect of incomplete charge collection due to mutual induction in neighboring cells and hole trapping currently limits the usefulness of the CdZnTe technology as compared to NaI technology. Improved crystal quality and more complicated electronics are required in order commercially implement this technology in the field of nuclear medicine