Revolution 256 CT胸部低剂量扫描不同噪声水平与后置ASIR-V权重的最佳组合

Low Dose Chest Scanning Scheme with the Best Combination of Revolultion 256CT Different Noise Levels and Posterior ASIR-V Weights

目的探讨Revolution 256CT胸部低剂量扫描不同噪声指数(NI)水平与后置ASIR-V权重的最佳组合。方法随机将320例胸部健康体检者分为4组:常规剂量组(NI15)和低剂量组(NI25、30、35),每组80例,均与后置ASIR-V不同权重(0~100%)相结合。测量计算感兴趣区噪声(SD)值、信噪比(SNR)、对比噪声比(CNR)、剂量容积指数(CTDIvol)、剂量长度乘积(DLP)及有效辐射剂量(ED),并对图像进行主观评分,得出最佳噪声指数(NI)及后置ASIR-V权重的组合。客观指标比较用方差分析,主观指标比较用Kappa一致性检验,P<0.05为差异有统计学意义。结果(1)随着ASIR-V权重的增加SD值逐渐减小、SNR及CNR值逐渐增加,差异有统计学意义(F=1.216~39.410,P<0.05)。(2)随着NI值的增加,SD值逐渐增加,SNR及CNR值逐渐减小,差异有统计学意义(F=1.216~39.410,P<0.05)。(3)随着NI值的增加,CTDIvol、DLP、ED值逐渐减小,差异有统计学意义(F=140.221~153.169,P<0.05),3组低剂量组较常规剂量组ED分别降低约68%、79%、84%。(4)主观评分一致性较好(Kappa=0.888,P﹤0.05),在NI15结合30%ASIR-V权重、NI25结合40%ASIR-V权重;NI30结合50%ASIR-V权重;NI35结合60%ASIR-V权重时最高。结论Revolution 256CT胸部低剂量扫描最佳NI及后置ASIR-V权重组合为NI15结合30%ASIR-V权重、NI25结合40%ASIR-V权重、NI30结合50%ASIR-V权重及NI35结合60%ASIR-V。

Objective To investigate the optimal combination of different noise levels and ASIR-V weights in low dose chest scanning with Revolution 256CT.Methods A total of 320 healthy subjects were randomly divided into four groups:conventional dose group(NI15)and low dose group(NI25,30,35),80 people in each group,which were combined with different weights(0-100%)of ASIR-V.Region of interest(ROI)noise(SD),signal-to-noise ratio(SNR),contrast to noise ratio(CNR),dose volume index(CTDIvol),dose length product(DLP)and effective radiation dose(ED)were measured and calculated.The image was scored subjectively to obtain the combination of optimal noise index(NI)and ASIR-V weight.Objective indicators were compared by ANOVA,and subjective indicators were compared by Kappa consis-tency test.P<0.05 indicates statistical significance.Results(1)With the increase of ASIR,the SD value gradually decreased,and the SNR and CNR values gradually increased,and the differences were statistically significant(F=1.216-39.410,P<0.05).(2)With the increase of NI value,SD value gradually increased,SNR and CNR values gradually de-creased,and the differences were statistically significant(F=1.216-39.410,P<0.05).(3)With the increase of NI value,the values of CTDIvol,DLP and ED gradually decreased,and the differences were statistically significant(F=140.221-153.169,P<0.05).Compared with the conventional dose group,the effective radiation doses of the three low-dose groups were reduced by about 68%,79%and 84%,respectively.(4)Subjective score in NI15 combined with 30%ASIR-V weight,NI25 combined with 40%ASIR-V weight;NI30 combined with 50%ASIR-V weight;NI35 combined with 60%ASIR-V weight was the highest.The optimal combination of NI and ASIR-V weights was NI15 combined with 30%ASIR-V weight,NI25 combined with 40%ASIR-V weight,NI30 combined with 50%ASIR-V weight,and NI35 combined with 60%ASIR-V weight in the Revolution 256CT chest low-dose scan.