Abstract: Objective To investigate the impact of different slice thicknesses and kernels on image quality of coronary CT angiography (CCTA) using photon-counting CT (PCCT), and to identify the optimal reconstruction parameters. Methods A total of 40 patients with suspected coronary artery disease (CAD) who underwent CCTA at Nanjing Drum Tower Hospital from June to August 2025 were prospectively enrolled. Images were reconstructed using three kernels (Bv40, Bv48, Bv56) and two slice thicknesses (0.4 mm, 0.6 mm). Quantitative measurements of CT attenuation, image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and peak signal-to-noise ratio (PSNR) were performed at the aortic root and coronary arteries. A linear mixed-effects model was used to analyze the main and interaction effects of the kernel and slice thickness. Box plots and correlation analysis were conducted to assess image stability and parameter relationships. Results Although thin-slice reconstruction combined with sharper kernels enhanced edge sharpness, it significantly increased image noise and reduced image stability. The Bv56 + 0.4 mm combination yielded the highest noise level and the lowest SNR and CNR. The Bv40 + 0.6 mm combination demonstrated the best performance across multiple metrics, including image noise, SNR, CNR, and PSNR. Box plots showed this parameter combination had the smallest interquartile ranges, indicating minimal parameter fluctuation.The kernel type was the most dominant factor affecting all image quality metrics (all P<0.01).No significant interaction effect was found between the kernel and slice thickness. Conclusions For CCTA using PCCT, the Bv40 kernel + 0.6 mm slice thickness provides an optimal balance between spatial resolution and noise control, achieving superior image quality and consistency.

Key words: photon-counting CT, image quality, kernel, slice thickness