螺旋CT机及其机房放射防护检测与评价研究

目的：评价螺旋CT机及其机房防护状况。方法：依据国家标准对25台螺旋CT机的加权剂量指数（CTDIw）和容积剂量指数（CTDIvol）及机房周围环境辐射水平进行检测与评价。结果：头部扫描的CTDIw、CTDIvol平均值分别为（40.2±18.1）mGy和（46.1±15.5）mGy,腹部扫描的CTDIw、CTDIvol平均值分别为（19.1±12.4）mGy和（20.3±12.1）mGy,19台（76%）CT机剂量指数符合要求。CT机房扫描室防护门处的辐射水平最高,并有2处超过防护限值,机房合格率为92%。结论：CT剂量指数直接关系到受检者的照射剂量,应定期进行检测和维护,合理选择扫描条件;对新建和改建的CT机房应做好防护设计审查,并注意选择安装位置。

Detection and evaluation of radiological protection for spiral CT machine and room

Objective To evaluate the present situation of radiological protection for spiral CT machine and room.Methods The weighted CT dose indexes（CTDIw） and volume CT dose indexes（CTDIvol） of 25 spiral CT machines were detected and evaluated according to national standards, which had the radiation level in the machine rooms tested also.Results The mean values of CTDIwand CTDIvolfor the head were（40.2±18.1）mGy and（46.1±15.5） mGy respectively,while the ones for the abdomen were（19.1±12.4） mGy and（20.3±12.1） mGy respectively. There were 19 machines（76%） met the requirements of the standards. The radiation level reached the highest at the doors, which were beyond the limit at two points. The machine room had a qualification rate of 92%. Conclusions CT dose index is related to the radiation dose of CT examination directly and should be detected and adjusted periodically. The CT room must be designed and examined on the basis of radiation protection requirements before it is constructed or reconstructed.