目的 本研究通过评价低辐射剂 量与低对比剂剂量下的前门控CT冠脉造 影图像质量与辐射剂量，明确该项扫描- 注射技术的有效性。方法 本研究共连续 选取31例病人，心率(heart rate，HR) ＜75次/min、心率变异度(heart rate variability,HRv)＜5次/min、体质量指 数(body mass index,BMI)≤26Kg/m2 ，体 质量(body mass,BM)≤65Kg。BM≤55Kg 采用2.5ml/s流率，55Kg＜BM＜60Kg采 用3.0ml/s流率，BM≥60Kg采用3.5ml/ s流率，BMI≤22Kg/m2 管电压80kV，管 电流400mA，22Kg/m2 ＜BMI＜26Kg/m2 管 电压80kV，管电流600mA。评价图像质 量、对比剂剂量及辐射剂量。检验水准 α=0.05。结果 31例病人冠脉节段平均分 数为2.62±0.81分，可评估率为98.21%。 主动脉根部衰减值为411.26±72.25HU， 噪声值为40.19±9.77HU，SNR为 10.58±2.21，CNR 为13.52±2.79。有 效剂量为1.28±0.39mSv，对比剂剂量为 32.26±3.83ml。结论 对于低体质量及低 体质量指数病人，通过降低管电压、降低 对比剂剂量行CTCA扫描可以在获得可评估 图像质量的同时大幅减低辐射剂量与对比 及剂量。

Objective To evaluate the value of low voltage CTCA in low body mass and low body mass index patients with low contrast media dose and radiation dose. Methods 31 patients (BM<65kg and body mass index <26kg/m2 ) were enrolled. All of patients with tube voltage and tube current tailored to BMI(BMI≤22Kg/m2 :tube voltage 80kV, tube current 400mA.22Kg/m2 ＜BMI＜26Kg/m2 : tube voltage 80kV, tube current 400mA), the flow rate and volume of contrast madia tailored to BM(BM≤55K:2.5ml/ s and 25ml, 55Kg＜BM＜60Kg: 3.0ml/s and 30ml, BM≥60Kg: 3.5ml/s and 35ml). Patients were evaluated by image quality(each coronary artery scale,attenuation,noise,SNR and CNR),contrast madia dose and radiation dose. P value below 0.05 was considered to be statistically significant. Results All patients successfully underwent low dose CTCA. The mean image quality score was 2.62±0.81. The percentage of assessable coronary artery segments was 98.21% .The mean attenuation was 411.26±72.25HU. The mean noise was 40.19±9.77HU. The mean SNR was 10.58±2.21. The mean CNR was 13.52±2.79HU.The mean effective dose was 1.28±0.39mSv.The mean contrast madia dose was 32.26±3.83ml. Conclusions Low dose CTCA may decrease the contrast media dose and radiation dose and keep image quality in patients with low body mass and body mass index.