儿童埋伏牙多层螺旋CT检查中的辐射剂量评价

Evaluation of radiation dose in multislice spiral CT scan for children embedded teeth

目的探讨适合儿童埋伏牙多层螺旋CT（MSCT）检查的低剂量曝光条件。方法80例经16层螺旋CT检查出埋伏牙的患儿，按曝光量不同分为5、25、125及250mAs4组，由放射科2名正主任医师及3名副主任医师采用双盲法评价图像质量，并记录不同毫安秒扫描时的加权CT剂量指数（CTDIw）、剂量长度乘积（DLP），使用SAS9．1统计分析系统进行统计学处理。结果4组的扫描图像均能准确显示埋伏牙结构及其相邻关系。5mAs扫描组在牙槽突骨小梁及牙龈等周围软组织的分辨能力较25、125及250mAs组下降，但仍能满足诊断要求。5mAs组CTDIw值及DLP值仅为250mAs组的2％。结论5mAs的MSCT低剂量扫描可以满足儿童埋伏牙诊断需要，减少了患儿接受的辐射剂量。

Objective To evaluate the radiation dose in both low radiation dose and to conventional radiation dose mode in muhislice spiral CT scan for children with embedded teeth, and explore the lowest conditions of exposure in multislice spiral CT scan for children embedded teeth. Methods Eighty cases of children with embedded teeth examined by 16 slices spiral CT were divided into 5,25, 125 and 250 mAs scanning groups. The scanned pictures of four groups were evaluated by two chief physicians and three associate chief physicians in the radiologieal department with double blind method. The CTDIw and DLP in different radiation dose mode were recorded and analyzed with statistics. Results All the four groups scanned pictures in different radiation dose mode could accurately show the structure and the adjacency relation of embedded teeth. Even though the resolution of scanned pictures in 5 mAs group were inferior to the other three groups on bone trabecula, gingiva and their surrounding soft tissue, it still could meet the requirements of examination. The average DLP in 5 mAs group was only 2% of value in 250 mAs group. Conclusions MSCT in 5 mAs group can not only meet the requirements of examination, but also reduce the radiation dose to patients to the greatest extent.