低剂量螺旋CT扫描对儿童髋关节图像质量的影响

Effect of low-dose exposure helix CT scan on image quality for children＇s hip joint

目的探讨儿童髋关节CT检查时降低管电流对图像质量的影响。方法随机选儿童髋关节CT扫描45例，分常规剂量组、低剂量Ⅰ组（〈6岁）和低剂量Ⅱ组（6～12岁）。记录容积CT剂量指数（CTDIvol）和扫描长度，计算出平均剂量长度乘积（DLP）。由专家对不同扫描参数的软组织窗和骨密度算法重建的骨窗图像质量分别进行评分，并进行统计学处理。结果常规剂量组、低剂量Ⅰ组和Ⅱ组的CTDIvol，分别为35．4、15．8、17．3mGy，DLP分别为（442．75±23．51）、（197．91±18．46）和（216．01±14．25）mGy·cm。各组可满足临床诊断要求的图像的比例差异无统计学意义（P〉0．05）。结论儿童髋关节CT检查时应采用低剂量扫描技术，既减少辐射剂量，又能保证图像质量，满足临床诊断的要求。

Objective To discuss the effect of reducing the tube current on the images quality in undergoing hip joint CT examination for children. Methods Forty-five patients were divided at random into three groups with different tube currents, namely group with routine dose, group Ⅰ aged less than 6 years with low dose and group Ⅱ aged from 6 to 12 with low dose. CT dose index （CTDIvol） and average dose-length produce （DLP） were detected. The image quality of three groups was analyzed by experienced ragiologists with score assessment and t-test. Results The CTDIvol values of three groups were 35.4,15.8 and 17.3 mGy, and those of DLP were 442.75 ±23.51,197.91± 18.46 and 216.01 ± 14.25 mGy· cm, respectively. The percentage of images meeting clinic diagnostic requirement was no significantly different （P 〉 0.05） in three groups. Conclusion Low dose helix CT scan for children＇s hip joint can meet the clinic diagnostic requirement.