单层与多层螺旋CT所致儿童受检者辐射剂量研究

目的 研究和评价儿童受检者在单层与多层螺旋CT扫描中所受到的辐射剂量。方法 测试21台CT机的头部和体部剂量指数,并结合0～1岁组、5岁组、10岁组儿童和成年人的头部和胸部常规扫描条件,计算CTDI_w、CTDI_vol、DLP值,再由DLP与有效剂量转换系数计算头部和胸部常规扫描所致各年龄组儿童和成年人的有效剂量。 结果 单位mAs的头部CTDI大于体部CTDI;在头部常规扫描中,0～1岁组、5岁组、10岁组儿童受到的有效剂量分别为2.2、1.3、1.1 mSv;在胸部常规扫描中,0～1岁组、5岁组、10岁组儿童受到的有效剂量分别为5.3、3.1、3.4 mSv;每单位mAs所致儿童有效剂量平均比成人高1.8倍;多层CT的儿童头部CTDI_vol、DLP、有效剂量值均大于单层与双层CT,多层与双层CT的儿童胸部CTDI_vol、DLP、有效剂量值均小于单层CT。 结论 与成年人相比,儿童在CT检查中可能受到更大辐射危害,应严格遵循儿童CT检查适应证,并合理选择CT扫描参数,尽可能降低儿童受到的辐射剂量。

Study on children patient dose in single-detector and multi-detector row helical computed tomography

Objective To study and evaluate the radiation dose of children patient in single-detector and multi-detector row helical CT scan. Methods The head and body CT dose index of 21 CT scanners were tested.Then the values of CTDI_w,CTDI_vol and DLP were calculated combining with the parameters of routine head and chest scan for children of 0-1 year old group,5 years old group,10 years old group and adults.The effective doses of children of every age group and adults in routine head and chest scan were subsequently estimated from effective dose per DLP by age and the calculated values of DLP. Results CTDI per mAs is greater in the head than that in the body. In head routine scan,the effective doses of 0-1 year old group,5 years old proup and 10 year old group were 2.2,1.3 and 1.1 mSv, respectively.In chest routine scan,the effective doses of 0-1 year old group,5 years old group and 10 years old group were 5.3,3.1 and 3.4 mSv, respectively.Effective doses to children per mAs are equally 1.8 times higher than corresponding values for adults.The CTDI_vol,DLP and effective dose to children in head routine scan for MDCT were greater those that for single-detector CT and dual-detector CT.The CTDI_vol,DLP and effective dose to children in chest routine scan for MDCT and dual-detector row CT were smaller than that for single-detector row CT. Conclusions Children are more radiation risk in CT examination as compared with adults.So we should strictly abide by justification of children CT examination,and optimize the parameters of CT scan rationally in order to reduce the radiation dose to children patient as much as possible.