[The application of setting tube voltage and iodine delivery rate in weight-grouped for reducing the radiation and contrast medium dose in coronary CT angiography].

Objective: To evaluate the application value of reducing tube voltage and iodine delivery rate according to body weight in coronary CT angiography (CCTA). Methods: A prospective randomized controlled study. A total of 297 subjects, 172 males and 125 females, aged [ M ( Q 1 , Q 3 )]60.0 (50.0, 68.0) years, who underwent CCTA examination in Peking University Third Hospital due to clinically suspected coronary heart disease from May to December 2022 were included. According to the odd or even visit dates, the subjects were randomly divided into test group ( n =156) and control group ( n =141). The subjects in both groups were divided into four sub-groups according to body weight: 50-59 group, 60-69 kg group, 70-79 kg group and 80-89 kg group, respectively. The CCTA images were reconstructed with hybrid iterative algorithm(KARL 3D) with levels of 6 and 8, respectively. 100 kVp and iodine flow rate 1.1, 1.3, 1.4 and 1.5 gI/s recommended by the domestic CCTA application guidelines were used in the control group, while the tube voltage and iodine flow rate were reduced in the test group based on the guidelines and body weight:70 kVp and 0.8 g I/s in 50~59 kg group, 80 kVp and 1.0 gI/s in 60~69 kg group, 80 kVp and 1.1 gI/s in70~79 kg group, and 100 kVp and 1.5 gI/s in 80~89 kg group, respectively. The CT values and standard deviation ( SD ) of aortic root, proximal left anterior descending branch (LAD) and distal right coronary artery (RCA) luminal CCTA, the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of coronary artery CT images, subjective coronary scores and effective radiation dose (ED) were compared between the both groups. One-way ANOVA or Wilcoxon test was used to analyze the differences of above indicators between the groups to evaluate the application value of low voltage and low iodine flow rate based on weight in coronary CCTA. Results: CT values of aortic root, LAD proximal CT values and SD values of aortic root [411.4 (377.2, 439.8) HU, (366.3±42.9) HU, 26.5±2.3] in the test group were all higher than those in the control group [379.00 (335.2, 415.9) HU, (355.0±46.9) HU and 24.8±2.3]. The differences were statistically significant (all P <0.05), and the other parameters were not statistically significant (all P >0.05). The total subjective image quality score in test group were superior to those in the control group (all P< 0.05). The total ED and contrast agent dosage [2.07 (1.52, 3.28) mSv and (38.28±9.68) ml] in CCTA examination in the test group were lower than those in the control group [3.30(2.32, 4.44) mSv and (45.31±5.63) ml], and the differences were statistically significant (all P <0.05). The dosage of ED and contrast agent in the test group was decreased by 37.3% and 15.5%, respectively. Conclusion: Combined with KARL 3D,it is feasible to reduce contrast medium and ED by setting the tube voltage and iodine flow rate of CCTA according to the weight of the subject, which can further reduce the radiation dose and contrast agent dosage of CCTA.