A randomized controlled study on isocenter scanning in reducing the radiation dose of multi-slice spiral CT coronary angiography

Abstract

Objective To investigate the value of isocenter scanning in reducing radiation dose in coronary artery multi-slice spiral CT angiography (MSCTA). Methods This is a prospective randomized controlled trial. A total of 144 patients with coronary artery MSCTA were collected in Guangdong Hospital of Traditional Chinese Medicine, Zhuhai Hospital from November 2016 to April 2018. They were randomly divided into groups A, B, C, and D, with 36 patients in each group. Group A was in conventional body position, and the current was intelligent milliampere; Groups B, C, D were in the isocenter body position, and the current was intelligent milliampere, 90% of intelligent milliampere, 80% of intelligent milliampere, respectively. The tube voltage of each group was 120 kV. The image quality noise, sigal noise ratio (SNR), subjective evaluation of image quality and radiation dose (ED) of images were compared among the four groups. The subjective image quality (the vascular diameter>1.5 mm) were evaluated by 15 sections method.The four sets of reconstructed images chosen from gas of primary bronchi which covers an area of about 15.0 mm2 was measured as noise value and SNR was its CT/standard deviation. Results Among the four groups, there was a statistically significant difference in the noise and SNR between group D with group A, B, C(all P values 0.05). The noise gradually decreased while the SNR gradually increased in the order of group D, A, C, and B(15.09±2.97, 2.68±2.47, 2.57±2.29, 2.45±4.36 and 63.74±19.78, 78.64±14.66, 78.66±14.84, 79.66±22.90). There was no statistically significant difference in the subjective scores of coronary arteries among the four groups(all P values>0.05). The subjective scores of coronary artery image quality were excellent in all 4 groups, and the good total rate was 98.9%(1 939/1 960). Radiation doses of A, B, C, and D group were (3.39±1.39) mSv, (2.89±1.21) mSv, (2.56±1.05) mSv, and (2.14±0.87) mSv, respectively.The radiation dose of group A was signficantly higher than group C and D(all P values<0.05). Conclusions An isocenter scan can reduce the radiation dose of coronary MSCTA without reducing the quality of coronary imaging. Key words: Tomography, Spiral Computer; Coronary artery; Isocenter scan; Radiation dose