目的 研究多层螺旋CT肺动脉成 像扫描技术的优化方法。方法 将56例临 床可疑肺栓塞的患者随机分为A、B两组， 每组各28例。采用对比剂自动跟踪触发和 自动触发管电流技术，行多层螺旋CT肺动 脉成像(CTPA)检查。A组为试验组，采用 管电压80kVp。B组为对照组，采用管电压 120kVp。测量肺动脉主干至双侧亚段肺动 脉的CT值，计算平均CT值。以肺动脉主干 CT值的标准差代表图像噪声，记录CT实际 容积剂量指数(CTDIvol)、剂量长度乘积 (DLP)、并计算有效剂量(ED)。计算图像 信噪比(SNR)及对比噪声比(CNR)，对图像 质量进行五级评分。结果 两组图像质量 评分统计学无显著性差异。A组辐射剂量 较B组下降38%，A组患者碘输入剂量较B组 下降19%。ROI监测平面选取上腔静脉层 面，阈值设定为100HU时图像显示清晰， 升主动脉此时无对比剂充盈，而肺动脉内 对比剂充盈良好，可清晰显示肺动脉及其 分支情况。40ml生理盐水比20ml生理盐水 冲洗后上腔静脉伪影明显减轻。结论 通 过优化肺动脉成像扫描技术条件，可以显 著降低患者所受辐射剂量和对比剂总碘量 的摄入，图像质量可以满足临床诊断需 求。

Objective To research optimizing the technology of multislice spiral CT pulmonary angiography. Methods The 56 patients with clinically suspected pulmonary embolism were randomly divided into A, B groups. Every group has 28 patients. Contrasting agent trigger automatic tracking technology and Tube current automatically triggered were used for multislice spiral CT pulmonary angiography (CTA) examination. Group A was test group with 80 kVp tube voltage. The superior vena cava was selected for ROI monitoring plane with the preset threshold of 80HU. The contrast agent used non-ionic contrast medium iohexol 300mgI/ml.The dose was 60ml.The injection rate was 4ml/s.The vein was immediately flushed with 40 ml brine after the contrast agent losers. Group B was contrast group with 120 kVp tube voltage. The pulmonary root opening was selected for ROI monitoring plane with the preset threshold of 100HU. The contrast agent used non-ionic contrast medium iohexol 370 mgI/ml.The dose was 60ml. The vein was immediately flushed with 20 ml brine after the contrast agent losers.The image quality was evaluated after lung CTPA scanning. Results There is no statistically significant difference between two sets of image quality. The radiation dose of Group A was decreased 38% than group B. The entered iodine dose of Group A patients was decreased 19% compared with group B. The image was clarity with superior vena cava as the ROI detection plane and 80HU as the threshold . In this case the ascending aorta without contrast agent filling,The pulmonary angiography was agent filled favorably. The artifacts of the superior vena cava of 40ml saline was significantly reduced than 20ml. Conclusion By optimizing conditions of pulmonary imaging scanning,it can significantly reduce the radiation dose and the intake of the total iodine. The image quality can meet the needs of clinical diagnosis.