Ultra-low-dose coronary computed tomography angiography using photon-counting detector computed tomography.

Aims: Photon-counting detector computed tomography (PCD-CT), which allows the exclusion of electronic noise, shows promise for significant dose reduction in coronary CT angiography (CCTA). This study aimed to assess the radiation dose and image quality of CCTA using PCD-CT, combined with high-pitch helical scanning and an ultra-low tube potential of 70 kVp, and investigate the effect of a sharp kernel on image quality and stenosis assessment in such an ultra-low-dose CCTA setting.

Methods And Results: Forty patients (65% male) with stable heart rates and no prior coronary interventions were included. Data on CT dose index volume (CTDIvol) and dose-length product (DLP) were collected, with effective radiation dose estimated using a conversion factor of 0.014. Images were reconstructed using kernels of Bv64 and Bv40 for image quality and stenosis assessment. The mean CTDIvol, DLP, and effective dose of CCTA were 1.72 ± 0.38 mGy, 29.1 ± 6.8 mGy·cm, and 0.41 ± 0.09 mSv, respectively. Image quality was similar ( = 0.75) between the two kernels, with over 95% of segments achieving a rating of good image quality for both kernels. The per-segment stenosis score distribution between Bv40 and Bv64 reconstruction images showed significant differences for both non-calcified and calcified plaques ( < 0.001 for both).

Conclusion: PCD-CT technology with high-pitch helical scanning and the tube potential of 70 kVp can provide CCTA with ultra-low radiation exposure (DLP, 29 mGy·cm). The noise reduction capability of PCD-CT allows the use of a sharp kernel even in this low-dose CCTA setting without compromising image quality, potentially improving the evaluation of coronary artery stenosis.