64层螺旋CT低剂量扫描技术在儿童上颌埋伏牙诊断中的应用

目的探讨64层螺旋CT在儿童上颌埋伏牙诊断中的低剂量扫描技术。方法收集我院75例上颌埋伏牙患儿,随机分为A,B,C 3组,分别采用90,60,40的有效毫秒数值（mAs）进行扫描,由2名副主任医师采用双盲法分析图像质量并打分,同时记录不同有效mAs时的剂量长度乘积（DLP）,并进行统计学处理。结果 3组图像均能清晰区分牙齿结构,重建图像质量无明显差异;B组和C组的图像牙齿锐利度、牙槽突骨小梁的分辨力较A组依次下降,但仍能满足诊断要求;C组与A组比较,DLP值显著下降（P〈0.05）。结论有效mAs为40的低剂量扫描技术可以满足儿童上颌埋伏牙的诊断需要,并能显著降低患儿接受的辐射剂量。

Clinical application of low-dose scan of 64-slice spiral CT in the diagnosis of maxillary impacted teeth

Objective To investigate the low-dose scan of 64-slice spiral CT for the diagnosis of impacted teeth. Methods 75 patients with impacted teeth were randomly divided into three groups,the effective mAs was 90 mAs in group A,in group B was 60 mAs and in group C was 40 mAs,additionally the dose-length produce（ DLP）was recorded in the three groups respectively,the quality of image was evaluated and scored by 2 radiologists at double-blinded,and the results were performed statistic analysis. Results Three sets of images could clearly demonstrate distinction between the structure of teeth,no statistical differences in the reconstructed image quality. Images of group B and group C compared with group A,accompanied by mAs declined,the sharpness of teeth and alveolar bone trabecular resolution decreased,but still able to meet the diagnostic requirements. The mean of DLP group C had significantly decreasing compared with group A（ P〈 0. 05）. Conclusion The low-dose scan in 40 mAs not only reduced the radiation dose of patients but also met the diagnosis of impacted teeth requirements.