Dose-efficient characterization of coronary artery plaques with a prototype CdZnTe-based photon-counting CT scanner

Photon-counting detector (PCD) bring multiple advantages, including higher contrast, lower noise, and improved spatial resolution compared to the conventional energy-integrating detector (EID) scanners. We investigated the image quality performance of a prototype CdZnTe-based photon-counting detector (PCD) CT scanner in this phantom study. We performed a phantom study 3D-printed inserts which mimicked coronary artery plaques along with calibrated concentrations of iodine, water, soft plaque (fat), and hard plaque (calcium). The phantom was scanned with similar settings on a CdZnTe-based PCD-CT system and a comparable state-of-the-art EID-CT system. Image noise, CT number stability, and CNR were measured in matched circular regions of interest. PCD-CT demonstrated ~50% lower noise compared to EID-CT across all x-ray exposures. Both systems showed a CT number deviation due to noise in the ±2 HU range. CNR across iodine, soft and hard plaques, and water showed improvement in the 201%-332% range for PCD-CT over EID-CT. Lastly, in a noise-matched setting PCD-CT can achieve similar image quality as EID-CT at 25% of the radiation dose.