儿童肺部CT曝光参数及其辐射剂量的比较分析

目的优化儿童肺部CT曝光参数，减少其辐射危害。方法对疑有肺部病变的儿童及青少年210例，降低曝光量行肺部CT扫描，以肺部支气管分叉层面的胸廓前后径和横径线长的平均值为依据，以儿童常规曝光量的70％为起始扫描剂量，逐次减少曝光量10mAs，观察其成像质量，直至图像质量良好，符合诊断的要求，并分析其曝光量mAs和单次扫描的CT剂量加权指数CTDIW及剂量长度乘积DLP。结果与儿童常规肺部曝光量200mAs相比，不同肺部发育的个体，其肺部CT曝光量可降低到其常规曝光量的45％～80％，单次扫描的CT剂量加权指数CTDIW及剂量长度乘积DLP均可降至27．45％～80％。结论根据儿童胸部个体发育差异，适当地降低曝光量，可以有效地降低其辐射剂量，减少其辐射危害。

Comparative study of pediatric lung CT scanning parameters and radiation doses

Objective To optimize CT scanning parameters in pediatric lung examination and reduce its radiation hazards. Methods According to mean anterior-posterior diameter and transverse diameter of thoracic cavity, 210 children with clinically suspected lung diseases were scanned by CT. The initial CT scanning dose was 70% of the conventional dose in lung examination. Then the scanning dose per scan was reduced by 10 mAs each until the quality of CT images was beyond the diagnosis demands, and the exposed doses, single scanning CT dose index weighted (CTDIW) and dose length product (DLP) were analysed. Results Compared with conventional lung CT scanning,the exposure value was reduced to 45%-80% according to individual development of pediatric lung, CTDIW and DLP of low dose scanning in pediatrics were reduced to 27.45%-80% respectively. Conclusion According to individual development of pediatric lung, CT scanning dose properly decreased in lung examination could reduce hazards of radiation to children.