Study on radiation dose and image quality for dual-source CT angiography under ‘double low’ Scan program / 中华放射医学与防护杂志

ABSTRACT

Objective To explore the image quality and radiation dose for coronary angiography using DSCT (dual-source computed tomography) under lower tube voltage and lower contrast agent concentration ('double low').Methods A total of 160 patients with suspected coronary artery disease underwent dual-source CCTA.80 patients (BMI ＜ 25 kg/m2) were randomly assigned to group A (270 mg I/ml-80 kV) and B (350 mg I/ml-120 kV).The other 80 patients (25 ≤ BMI ＜30 kg/m2) were randomly assigned to group C (270 mg I/ml-100 kV) and D (350 mg I/ml-120 kV),sonogram affirmed iterative reconstruction technology and 270 mg I/ml contrast agent were applied to group A and C ; FBP technology and 350 mg I/ml contrast agent were applied to group B and D.Adaptive cardio-sequence prospective ECG-gated technology was applied in all patients,while the acquisition phase was 65％-75％ RR interval (when heart rate ＜ 75 beats / min) or 40％-50％ RR interval at when heart rate ≥ 75 beats/min.Volume CT dose index (CTDIvol),dose length product (DLP),effective dose (E),size specific dose estimates (SSDE),image noise,CT value,signal-to-noise ratio (SNR),and contrast-to-noise ratio(CNR) were all evaluated for each patient.Results There was not statistical difference in scan length among groups A and B,C and D.There was statistical difference in tube current between group A and B (t =8.932,P ＜0.05).There was not statistical difference in tube current between group C and D (tCD =-1.212,P ＞ 0.05).There was statistical difference in CTDIvol,DLP,E and SSDE between group A and B,C and D (tCTDIvol =-16.141,-11.440 ; tDLP =-17.454,-10.521 ; t =-17.444,-10.523 ;tSSDE =-13.032,-9.119,P ＜0.05).Compared to group B,the SSDE in group A decreased by 64.4％.Compared to group D,the SSDE in group C decreased by 39.3％.There was no statistical difference in image noise between group A and B,C and D (P ＞ 0.05).There was statistical difference in CT value,SNR and CNR between group A and B (t =0.436,4.623,3.272,P ＜ 0.05).There was no statistical difference in CT value and CNR between group C and D,while there was statistical difference in SNR between group C and D (t =2.981,P ＜0.05).There was no statistical difference in image quality scores between group A and B,C and D (P ＞ 0.05).Conclusion Compared with conventional DSCT coronary angiography,'double low' DSCT coronary scanning solution can significantly reduce the radiation dose and contrast agent,and could provide the effective coronary images which meet the clinical diagnostic needs.