To explore current status of scanning protocol and radiation dose of coronary CT angiography (CCTA) in China from 2017 to 2018.

Cluster sampling was conducted according to the number and distribution of tertiary and secondary hospitals in provinces across the country, and 75 hospitals (30 secondary hospitals and 45 tertiary hospitals) were finally included. The patients who underwent CCTA from October 2017 to May 2018 were systematically sampled, and 1 312 patients were finally included. Patients were divided into two groups according to the level of hospital. Basic clinical characteristics were collected, including age, sex, height, weight, CT scanning equipment, scanning parameters, scanning model, post-processing scheme and radiation dose. Wilcoxon rank sum test, χ² tes were used in statistical analysis. Radiation dose was compared between different tube voltage, scanning model and post-processing solutions groups.

The ratio of employing low tube voltage (≤100 kV) was 35.4% (464/1 312). The rate of using low tube voltage in different weight groups (<60, 60-90,>90 kg) were 45.0%(126/280), 39.6%(256/647), 33.3%(8/24) in tertiary hospitals respectively, and 27.8%(25/90), 18.5%(49/265), 0(0/6) in secondary hospitals respectively. The rate of using low tube voltage in different weight groups (<60, 60-90,>90 kg) was significantly higher in tertiary hospitals than in secondary hospitals (χ²=34.25, 51.05, 207.05, P<0.001). Prospective electrocardiogram triggering model was used in 38.5% (505/1 312) of the patients. Application rate of iterative reconstruction was 82.5% (1 082/1 312). Among the patients who applied iterative reconstruction, tube voltage of 120 kV and above was used in 58.8% (636/1 082) of the patients. The effective radiation dose (ED) of CCTA was 11.84 (6.33, 16.66) mSv. The ED of CCTA examination in tertiary hospitals was slightly lower than that of secondary hospitals (Z=-5.73, P<0.001). The ED of CCTA examination using prospective electrocardiogram triggering model was lower than that of retrospective electrocardiogram triggering model (Z=-15.76, P<0.001). The ED of CCTA examination with iterative reconstruction [11.76 (6.94, 17.58) mSv] was slightly lower than those without iterative reconstruction (Z=-3.45, P=0.004).

The problems were focused on tube voltage fixation, low application proportion of low tube voltage and prospective electrocardiogram triggered protocol, and nonstandard application of iterative reconstruction technology during CCTA examination in the investigated hospitals. The nonstandard scanning protocol was an important causation of high ED in CCTA examination. Although the scanning standardization degree of tertiary hospitals was higher than that of secondary hospitals, but it still did not meet the guidelines.

Tomography, X-ray computed; Coronary artery disease; Radiation dosage; Scanning technique