儿童副鼻窦低剂量双螺旋CT轴位扫描多平面重组的应用研究

目的探讨儿童鼻窦低剂量双螺旋轴位扫描多平面重组技术的可行性和合理的扫描参数。方法 50例正常或轻度鼻窦炎年龄1～15岁儿童按扫描参数随机分为5组,每组10例。第1～3组电压120 kV,电流分别为100 mAs、50 mAs、30 mAs;第4组电压100 kV,电流30 mAs;第5组电压80 kV电流30 mAs。用Kruskal-Wallis H检验和Nemenyi法比较各组图像质量有无差异。结果第2～5组的容积CT剂量指数（CTDIvol）与第1组的CTDIvol比较分别减少50%、70%、82%、91%。5组图像质量评分结果之间有显著差异性（χ2=54.15,P〈0.0001）;其中,第2~4组与第1组、第3~4组与第2组、第4组与第3组比较图像质量评分之间无显著差别（χ2=0.19、2.32、0.83、1.19、0.23、0.38,P〉0.05）;第5组与第1~4组比较图像质量评分之间有显著差别（χ2=40.88、35.55、23.74、30.09,P〈0.01）。结论儿童鼻窦低剂量双螺旋轴位扫描多平面重组是可行的,扫描参数低至100 kV,30 mAs,CTDIvol 4.6 mGy仍可满足临床诊断要求。

Study of low dose axial scan of pediatric paranasal sinuses with 2-slice spiral CT multiplanar reconstruction

Objective To study the application of low-dose 2-slice spiral CT scan technique in examining pediatric paranasal sinus.Methods Fifty children with normal paranasal sinus and mild paranasal sinusitis examined by PHILIPS MX4000 Dual CT were collected.According to scanning parameters these cases were divided into 5 groups（each group 10 cases）,group 1,2,3 were scaned by 120 kV,100 mAs,50 mAs,30 mAs;group 4 by 100 kV,30 mAs,group 5 by 80 kV,30 mAs.Other scan parameters were fixed.Image quality of each group was compared each other by using Kruskal-Walls test and Nemenyi test to see whether there was difference between varied groups.Results Compared with group 1,CTDIvol of group 2 to 5 were reduced by 50%,70%,82%,91%,respectively.No significant difference was found between group 1 and group 2 to 4（χ2=0.19,2.32,0.83,P 0.05） but there was significant difference between group 5 and group 1,2,3,4（χ2=40.88,35.55,23.74,30.09,P 0.01）.Conclusion Low dose 2-slices spiral CT scanning can be used in the paranasal sinus examinations of children,low dose CT scan with 100 kV,30 mAs（CTDIvol 4.6 mGy） can satisfy the diagnostic requirements.