目的评估低辐射、低对比剂用 量(双低)技术用于大体重患者320排动态 容积CT冠状动脉成像(CCTA)的图像质量 及辐射剂量。方法 前瞻性纳入临床拟诊 冠心病且体重＞90Kg患者86例，随机分 为实验组B和对照组A。A组，44例，使用 120Kv管电压，碘佛醇320mgI/mL对比剂； B组，42例，使用100Kv管电压，威视派克 270mgI/mL对比剂；A、B两组均使用智能 毫安技术，对比剂用量均为0.625mL/Kg； 采用东芝Aquilion One前瞻式心电门控扫 描、三维自适应迭代重建算法(3D AIDR) 降噪。分别测量主动脉根部、左主干 (LM)、左前降支(LAD)、左回旋支(LCX)、 右冠状动脉(RCA)的CT强化值进行组间统 计学比较，同时比较两组间噪声(SR)、对 比噪声比(CNR)、有效辐射剂量(ED)，进 行统计学分析。结果 A、B两组图像中各 支血管CT值差异均无统计学意义(P＞0.2 for all)，B组ED为：(3.68±2.19)mSv低 于A组：(8.16±5.55) mSv(P＜0.05),平 均减少了54%。结论 低辐射、低对比剂量 (双低）技术用于大体重患者可以获得不 差于常规辐射和对比剂用量条件下的图像 质量，有利于降低X线和碘对比剂对患者 带来的危害。

Objective To evaluate the image quality and radiation dose of 320-slice volume CT coronary angiography (CCTA) in patients with large body weight using low radiation and low contrast agent dosage. Methods 86 patients with coronary heart disease and weight 90Kg were randomly divided into experimental group B and control group A. A group, 44 cases, using 120Kv tube voltage, 320mgI/ml contrast agent ioversol, group B, 42 cases, using 100Kv tube voltage, Visipaque 270mgI/ml contrast agent. A, B two groups using the intelligent Ma technology, contrast agent dosage was 0.625ml/Kg, using Toshiba Aquilion One prospective ECG gated scanning, 3D adaptive iterative reconstruction algorithm (3D AIDR) and noise reduction. The aortic root were measured, left main (LM), left anterior descending (LAD), left circumflex and right coronary artery (LCX) (RCA) CT enhancement value between groups were compared between the two groups at the same time, noise (SR), contrast to noise ratio (CNR), effective radiation dose (ED), statistical analysis. Results A, B two groups of image in the vessels of CT showed no significant difference (P>0.2 for all B), group ED: (3.68±2.19)mSv than in the A group: (8.16±5.55)mSv (P<0.05), decreased by 54%. Conclusion Low dose radiation and low contrast (double low) technique for image quality may be obtained in conventional radiation and contrast agent under the condition of general weight patients, to reduce the X-ray and iodine contrast agent brings harm to the patients.