多模型自适应统计迭代重建算法对降低腰椎CT辐射剂量的作用

The effect of multi-model adaptive statistical iterative reconstruction-V on reducing the radiation dose of lumbar CT

目的:应用Revolution CT多模型迭代重建算法(pre Asir-V)行腰椎扫描降低辐射剂量的可行性研究。方法:选取BMI 25～29间的60例拟行腰椎CT扫描患者随机分为3组,A组(0%ASIRV重建算法组),B组(40%ASIR-V重建算法组),C组(60%ASIR-V重建算法组)。3组KV设置为120,噪声指数NI设置为10,结合自动mA调节技术,SmartmA默认为100～700,记录并计算有效辐射剂量(ED),对比L4-5水平各组图像感兴趣区(L4-5平面椎间盘、硬膜囊、右侧腰大肌及L4椎体松质骨)的客观评价指标:信噪比(SNR)、椎间盘与硬膜囊对比噪声比(CNR)和主观评分,行统计学分析。结果:B组有效辐射剂量ED[(4.47±0.62)mSv]较A组ED[(6.66±0.84)mSv]平均降低约33%,C组有效辐射剂量ED[(3.51±0.70)mSv]较A组平均降低约47%,B组各感兴趣区SNR、CNR与A组SNR、CNR无显著统计学差异(P>0.05);C组各感兴趣区SNR、CNR与A组SNR、CNR无显著统计学差异(P>0.05);除椎小关节,A、B、C组图像主观评分无显著性差异,观察者间一致性很好。结论:与常规剂量扫描相比,低剂量扫描参数结合适当的迭代重建算法在明显降低辐射剂量的同时不影响图像质量。

Objective:To explore the feasibility of lumbar CT scanning with reduced radiation dose using adaptive statistical iterative reconstruction-V(ASiR-V)of revolution CT.Methods:Sixty patients were randomly divided into 3 groups:group A(n=20)with 0%ASiR-V,group B(n=20)with 40%ASiR-V,group C(n=20)with 60%ASiR-V.There were other parameters:120kV,noise index(NI)10,SmartmA 100~700mA.Signal-to-noise ratio(SNR)was measured on the L 4-5 intervertebral disc,dural sac,right psoas muscle and L 4 vertebral cancellous bone.Contrast-noise-ratio(CNR)was measured on intervertebral disc and dural sac.Image quality was calculated by two radiologists and effective radiation dose(ED)was compared.Results:A(6.66±0.84mSv)was reduced by 33%compared with group B(4.47±0.62mSv).ED in Group C(3.51±0.70mSv)was reduced 47%compared with group A(6.66±0.84mSv).There was no significant difference in SNR or CNR between group B and group A,or between group C and group A(P>0.05).There was no significant difference of subjective scores of image quality among three groups and the consistency between the observers was very good.Conclusions:Low dose scanning parameters combined with appropriate ASiR-V can significantly reduce radiation dose while not affecting image quality compared with routine dose scans.