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下肢CT血管成像低kVp和低mAs扫描对比研究
Comparison of low kVp and low mAs CT angiography of lower limbs
【摘要】 目的比较低kVp和低mAs技术在下肢血管CTA降低辐射剂量的优势。方法选取下肢CTA病例120例,低kVp组、低mAs组各60例。低kVp组使用90 kVp、250 mAs,低mAs组使用120 kVp、150 mAs。记录两组病例扫描长度L、容积CT剂量指数(CTDIvol及剂量长度乘积(DLP),计算有效剂量E值。测量腰3椎体水平图像信噪比(SNR)、对比噪声比(CNR)以客观评价图像质量;双盲法主观评价下肢动脉后重组图像质量并给予优、良、差分级。对L、CTDIvol、DLP、E值、SNR及CNR进行t检验,主观图像质量评价采用x2检验。结果低kVp组CTDIvol、DLP、E值比低mAs组降低28.3%,两组DLP、E值比较均有统计学差异(P<0.0001)。低kVp组和低mAs组SNR、CNR经统计学分析有差异(P值分别为0.019和0.009)。图像质量主观评判,低kVp组优级片达75%,低mAs组为65%,两组图像优、良两级质量满意率均达100%。结论下肢CTA采用低kVp技术较低mAs技术能够降低辐射剂量,并提高图像质量,可作为下肢CTA检查的常规检查。
【Abstract】 Objective To compare the radiation dose between low kVp and low mAs scanning techniques of lower limb computed tomography angiography(CTA).Methods 120 lower limb CTA was included in the study and divided into low kVp group(n = 60) and low mAs group(n = 60).90 kVp with 250 mAs was used in the low kVp group whereas 120 kVp with 150 mAs in the low mAs group.Scan length(L),volume computed tomography dose index(CTDIvol) and dose-length product(DLP) were recorded and the effective dose(ED) was calculated.The image quality was objectively evaluated by signal-to-noise ratio(SNR) and contrast-to-noise ratio(CNR) of tissues measured and calculated at level of 3rd lumbar vertebra.The image quality of post-processed lower limb arteries was subjectively scored as excellent,good or poor.The results of L,CTDIvol,DLP,ED,SNR and CNR were compared by t-test and the image quality compared by χ2 test.Results The CTDIvol,DLP and ED of low kVp group were 28.3%lower than those of low mAs group.The differences of DLP and ED between the two groups were significant 9t = 25.900,P< 0.0001).The SNR and CNR were also significantly different between the two groups(P = 0.019 and 0.009,respectively).Image quality was subjectively rated as satisfactory in all studies with excellent scores in 75%of the kVp group and 65%of the low mAs group.Conclusions The lower limb CTA with low kVp technique is superior to low mAs technique with lower radiation dose and better image quality.
- 【文献出处】 影像诊断与介入放射学 ,Diagnostic Imaging & Interventional Radiology , 编辑部邮箱 ,2013年02期
- 【分类号】R816.2
- 【被引频次】6
- 【下载频次】1