Affordable CZT Gamma Cameras with Minimal Dose-Exam Time

Objectives: Pixelated CdZnTe (CZT) detector arrays are currently used in molecular imaging applications that can enable precision medicine, including small-animal SPECT, cardiac SPECT, molecular breast imaging (MBI), and general purpose SPECT. The interplay of gamma camera and collimator design, gantry motion, and image reconstruction determines image quality and dose-time-FOV trade-offs. Both dose and exam time can be minimized using CZT gamma cameras without compromising diagnostic content. Methods: Integration of pixelated CZT detectors with advanced ASICs and readout electronics improves system performance. Because historically CZT was expensive, the first clinical applications were limited to small FOV. Radiation doses were initially high and exam times long. Advances have significantly improved efficiency of CZT-based molecular imaging systems and the cost has steadily declined. As a technology demonstration, we have built a general purpose SPECT system using our 40 cm x 53 cm CZT gamma camera and have characterized system performance. Results: Compared to NaI scintillator gamma cameras: intrinsic spatial resolution improved from 3.8 mm to 2.0 mm; energy resolution improved from 9.8% to < 4 % at 140 keV; maximum count rate is > 1.5 times higher; non-detection camera edges are reduced ~3-fold; scatter fraction is greatly reduced in the narrow photopeak energy window; image contrast is improved; and the optimal FOV is increased to the entire camera area. Conclusion: Ongoing improvements in CZT detector arrays for molecular imaging, coupled with optimal collimator design and image reconstruction, result in minimized dose and exam time. With CZT cost improving, affordable whole-body CZT general purpose SPECT is expected to enable precision medicine applications.