Assessing possible use of CZT technology for application to brain SPECT

Cadmium-Zinc-Telluride (CZT) detectors have recently emerged as an alternative to conventional NaI(Tl)-based Anger cameras for SPECT. CZT detectors have better energy resolution and are more compact than conventional gamma cameras. In this work we have assessed the use of CZT detectors in the design of a brain SPECT system. The proposed SPECT system consists of a number of detector arrays, placed in a circle around the patient. A potential advantage of this system would be the possibility to acquire fast dynamics for the central brain region. The design parameters initially investigated were the number of detectors, detector radius, collimator bore length, collimator geometry, as well as the possibility of ROI imaging. We used simulated data based on digital phantoms to compare various design options. The reconstructed images were evaluated by contrast vs. noise curves. Best results were obtained with a small number of detectors close to the object. The optimal collimator bore length was 30 mm. Diverging collimators gave results close to those from parallel-hole collimators. ROI reconstruction was found to be possible and diverging collimators outperformed parallel-hole collimators for this purpose. The ROI images were further improved by the use of partial volume correction in the reconstruction.