Achieving low radiation dose and contrast agents dose in coronary CT angiography at 60-kVp ultra-low tube voltage.

Objectives: To explore the feasibility of a one-beat protocol and ultra-low tube voltage of 60 kVp in coronary CT angiography (CCTA).

Methods: This prospective study enrolled 107 patients (body mass index ≤ 26 kg/m) undergoing CCTA examinations. Specifically, the conventional group (n = 52) underwent 100 kVp scanning with 45 ml iodine contrast agent and 4 ml/s injection rate, and the low-dose group (n = 55) underwent 60 kVp scanning with 28 ml iodine contrast agent and 2.5 ml/s injection rate. The CT value, signal-noise-ratio (SNR), contrast-noise-ratio (CNR) and subjective image quality score of two groups in aorta (AO), right coronary artery (RCA), left anterior descending (LAD) and left circumflex (LCX) are analyzed in this study. Three types of radiation doses [i.e., volume CT dose index (CTDIvol), dose length product (DLP), effective dose (ED)] of two groups are also compared.

Results: The quantitative results indicated that the low-dose group achieved higher CT values, SNR and CNR results of the AO than the conventional group (P values < 0.001). Both groups had similar CT values, SNR and CNR results in RCA, LAD, and LCX (P values > 0.05). A good agreement is noted with respect to subjective image quality scores in both groups, while the Cohen's kappa value is 0.815 in the low-dose group and 0.825 in the conventional group, respectively. In addition, the radiation dose of the low-dose group is significantly lower than the conventional group in terms of CTDIvol, DLP and ED values, and the contrast dose in the low-dose group is also significantly reduced compared to the conventional group (P values < 0.001).

Conclusions: One-beat protocol with an ultra-low tube voltage of 60 kVp could provide improved coronary image quality, reduced radiation dose and reduced iodine contrast dose.