Objective :Aim to evaluate the usage of low-dose CT scanning and iterative reconstruction in the accurate diagnosis of pulmonary embolism while decreasing the radiation dose and image quality not compromised . Methods :108 patients finally diagnosed as pulmonary embolism were reviewed and divided into three groups A ,B , and C .Patients in Group A were scanned under routine radiation dose (120kV ) and images were reconstructed by filtered back projection (FBP) ,while Group B radiation dose (100kV) ,FBP and Group C radiation dose (100kv) , iterative reconstruction (iDose) .the CT dose index volume (CTDI vol) ,dose length product (DLP) ,effective radia-tion dose (ED) ,The mean value of main pulmonary artery and dorsal muscles ,signal/noise ratio (SNR) ,contrast noise ratio (CNR) of the images in each group were recorded and compared .The image quality were graded and scored 1-5 ,according to these parameters .Results :Under subjective evaluation ,the image quality in three groups has no significant difference .Under objective evaluation ,group A ,B and B ,C has statistical difference (P< 0 .05) while no statistical difference (P> 0 .05)between group A ,C .Group B has the privilege of lower dose BUT louder noise and decreased SNR ,CNR ,compared with Group A .The image quality in Group C (iDose) surpassed that in group B (FBP) (P < 0 .01) .The effective dose (ED) of group B ,C was decreased by 18 .0％ ～ 19 .6％ compared with ED of group A .Conclusion :For patients diagnosed as pulmonary embolism ,low dose scan and iterative reco nstruction in CTPA (CT Pulmonary Angiography) can decrease the radiation dose effectively and provide accepted image quality ,which can be applied broadly in clinical work and research .%目的:探讨肺动脉栓塞患者行CT血管成像(CTPA)检查时,低辐射剂量及迭代重建技术联合应用,在降低辐射剂量的同时,保持图像质量,对肺动脉栓塞进行准确诊断的价值研究.方法:选择行CTPA检查的最终确诊肺动脉栓塞患者108例,分为常规辐射剂量(120kV)组和低辐射剂量(100kV)组.常规辐射剂量组(A组)采用滤波反投影(FBP)重建,低辐射剂量组分为FBP重建组(B组)及iDose迭代重建算法重建组(C组).对三组的图像进行重建 、测量和质量评分,记录CT剂量指数(CTDIvol)、剂量长度乘积(DLP)、计算有效辐射剂量(ED)及测量每例患者肺动脉主干 、背部肌肉的CT值均值,计算各组的噪声 、信噪比(SNR)、对比度噪声比(CNR).按1～5分评价总体图像质量,并对三组结果进行比较.结果:在三组患者CTPA检查图像主观评价中,常规辐射剂量A组与低辐射剂量B、C组比较,C组总体图像质量与A组比较意义无统计学意义;客观质量评价中,A、C组比较差异无统计学意义(P>0.05),A、B两组及B、C两组比较差异均有统计学意义(P<0.05).不同辐射剂量A、B两组比较,辐射剂量小,图像噪声相对增高,SNR及CNR减小.相同辐射剂量组,应用iDose迭代重建组(C组)图像质量均优于传统滤波反投影FBP组(B组)(P<0.01);辐射剂量评价中,低剂量组的有效辐射剂量(ED)较常规剂量组(A组)分别降低18.0％ ～19.6％.结论:肺动脉栓塞患者行CTPA检查时,采用低辐射剂量并联合迭代重建算法重建,可以在保持肺动脉图像质量不降低的基础上,显著减少有效辐射剂量,为其临床应用与推广研究提供可靠的依据.
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