中文摘要：

目的探讨低管电压（100 kVp）联合不同噪声指数（NI）和低浓度对比剂在肺动脉CTA（CTPA）中对图像质量、辐射剂量和碘摄入量的影响。 方法前瞻性收集疑诊为肺动脉栓塞及其他肺动脉疾病，拟行CTPA检查的80例患者，按随机数字表法将患者分成A、B、C、D组，每组20例。各组患者均行CTPA检查，A组管电压120 kVp，NI为25，对比剂浓度为含碘370 mg/ml；B、C、D组管电压100 kVp，NI分别为30、35、40，对比剂浓度为含碘320 mg/ml。4组均采用权重为60%的迭代重建算法。对图像质量进行客观评价（指标包括肺动脉CT值、肺动脉噪声、信噪比和对比噪声比）和主观评分，并记录碘摄入量和辐射剂量（包括CT剂量指数、剂量长度乘积、有效剂量）。采用方差分析或Kruskal-Wallis比较4组间图像质量、辐射剂量和摄入碘量的差异。结果4组间CTPA图像的肺动脉CT值差异有统计学意义（P〈0.05），A组最低；肺动脉噪声、信噪比和对比噪声比、主观评分差异均无统计学意义（P〉0.05）。4组患者的碘摄入总量分别为（340±109）、（298±97）、（295±88）和（289±77）g，差异有统计学意义（F=16.22，P〈0.01），A组最高，D组最低。B、C、D组较A组分别减少了12.4%（42/340）、13.2%（45/340）和15.0%（51/340）。4组患者的辐射剂量差异有统计学意义，A组最高，D组最低。D组的CT剂量指数、剂量长度乘积、有效剂量较A组分别减少了45.3%（3.9/8.6）、48.6%（120/247）和48.3%（2.02/4.18）。结论在保证影像质量不影响诊断前提下，低管电压联合高NI值及低浓度对比剂能够有效降低CTPA的辐射剂量和碘摄入量。

英文摘要：

ObjectiveTo investigate the image quality, radiation dose and iodine intake of CT pulmonary angiography （CTPA） in patients using low tube voltage （100 kVp） combination of different noise indexes （NI） and low concentration contrast agent.MethodsA total of 80 patients with suspected pulmonary embolism （PE） and other pulmonary diseases who had undergone CTPA were divided into four groups （A, B, C and D）, with 20 patients in each group. Group A underwent 120 kVp CT scan protocol in combination with NI=25 and 370 mg iodine/ml contrast agent, while groups B, C and D underwent 100 kVp CT scan protocol in combination with NI=30, 35, 40, and 320 mg iodine/ml contrast agent, respectively. All images were restructured using 60% adaptive statistical iterative algorithm 2.0. Objective image quality evaluation included CT values of pulmonary artery, noise values of pulmonary artery, signal-to-noise ratio （SNR） and contrast-to-noise ratio （CNR）. Subjective image evaluation used a 5-point scoring method and was conducted by two independent radiologists. The CT dose index of volume （CTDIvol）, dose-length product（DLP） and iodine intake was recorded, and the mean value was calculated. The DLP was converted to the effective dose （ED）. Analysis of Variance or Kruskal-Wallis test was used to evaluate the differences among the four groups in terms of image quality, radiation dose and iodine intake.ResultsThere was a significant difference in CT values of pulmonary artery among the groups A, B, C and D （P〈0.05）, and the CT values of pulmonary artery of group A was the lowest. There was no significant differences in noises of pulmonary artery, SNR, CNR and subjective indexes scores among the groups A, B, C and D （P〉0.05）. There was a significant difference in iodine intake among the groups A, B, C and D, iodine intake of the group A was the highest, iodine intake of the group D was the lowest. The iodine intake of groups B, C and D decreased by 12.4% （42/340） ,13.2% （45/340） and