Objective To evaluate the application of low kV with pitch scanning simultaneous iterative reconstruction algorithm for the effects over the enhancement of blood vessels and the image quality and radiation dose.Methods 40 cases of the patients suspected with pulmonary embolism were prospectively and consecutively enrolled, followed by subject to CT examination.Patients were randomly grouped into two, namely group A for routine dose of kV and group B for the low dose of kV, with each group having 20 cases.the two groups were subject to different scanning modes.Then group B is further subdivided into two groups, termed B1 and B2 which subject to different ways of reconstruction.By two radiologists subjective assessment of image was performed by two radiologists with five points method.the pulmonary artery trunk was measured, the ascending aorta and the CT value of muscle tissue around and noise were also measured.compared was the difference of image signal-to-noise ratio (SNR), contrast to noise ratio (CNR) and radiation exposure parameters, including volume CT dose index (CTDIvol) and dose length product (DLP) between A and B group.so did the B1 and B2 group.Meanwhile, the effective radiation dose (ED) was calculated using SPSS 17.0 version software.Results All images can meet the requirements of diagnosis.In addition, there was no significant difference of the three diagnostic schemes in terms of subjective and objective measurement of CT value, SD, SNR and CNR (P>0.05).While, there was statistically significant difference of CTDIvol and DLP between A and B group (P<0.01).Conclusion The joint use of low kV with increasing the pitch scanning at the same time in conjunction with ASiR scanning mode not only could meet the image diagnosis without lowering the quality but also could further reduce the effective radiation dose.%目的 评价应用低管电压(kV)并加大螺距扫描联合迭代重建算法对于血管强化程度、图像质量和辐射剂量的影响.方法 前瞻性连续选择可疑肺动脉栓塞的患者40例,行多层螺旋CT肺动脉造影检查.将患者随机分为A、B组(A组为高kV组,B组为低kV组),每组20例,两组患者分别接受不同的扫描模式;再将B组分为B1组和B2组,分别接受不同的重建方式.由2名放射科医师对图像用5分法进行主观评估,并测量肺动脉主干、升主动脉以及周围肌肉组织的CT值和噪声,并计算对照组和实验组以及实验组两亚组图像的信噪比(SNR)、对比噪声比(CNR),比较辐射曝光参数,包括CT容积剂量指数(CTDIvol)和剂量长度乘积(DLP),并计算有效辐射剂量(ED).结果 所有图像均满足诊断要求,3种方案的影像质量在主观评价及客观测量(CT值、SD、SNR、CNR)方面差异均无统计学意义(P>0.05),而B组辐射剂量(CTDIvol和DLP)明显低于A组,差异具有统计学意义(P<0.01).结论 应用低Kv和加大螺距扫描,并联合自适应统计迭代重建(ASiR)扫描模式,在不降低图像质量且满足图像诊断的同时还能进一步降低有效辐射剂量.
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