多排螺旋CT低剂量扫描在小儿胸部的应用  

The Application of Low-Dose MSCT on Pediatric Chest

作　　者：孔秋雁[1] 陈廷港[1] 许崇永[1] 陈宇[1] 吴爱琴[1] 

机构地区：[1]温州医学院附属第二医院CT室,浙江温州325027

出　　处：《实用放射学杂志》2007年第6期792-794,共3页Journal of Practical Radiology

摘　　要：目的评估低剂量扫描在小儿胸部的应用。方法水模测试:在水体模的同一层面做3mm层厚的150、80、50、35、15mAs扫描。在每幅图像的5个相同感兴趣区测CT值,做CT值的均匀性和噪声水平比较。病例扫描:随机选择肺部感染的患儿40例,先行常规剂量(150mAs)扫描以确定感染部位,再在感染局部做低剂量扫描(50,35mAs及15mAs)。其他参数为:120kV,床进28.8mm/圈,0.5s/圈,16×1.5mm准直,重建层厚及间隔均为3mm。比较不同剂量的CT权重剂量指数(CTDIw)及剂量长度乘积(DLP);由2位高年资医师按优、良、合格及不合格的等级盲法评价不同剂量的图像质量,结果进行统计学处理。结果CT图像的均匀性随着扫描剂量的减少而变差,图像噪声水平随扫描剂量的减少而增高。小儿胸部150、50、35、15mAs的CTDIw分别为:10.0、3.3、2.3、1.0mGy,其DLP分别为:117.8、39.3、27.5和11.8;150、50、35mAs的符合临床诊断图像(包括优,良,合格3个等级)所占比例,肺窗和纵隔窗均不小于90%,而15mAs的不合格图像所占比例为20%。结论在保证图像质量的前提下,多排螺旋CT小儿胸部检查采用35mAs的扫描条件较为适宜。Objective To evaluate the application of the low - dose in the pediatric chest multi - slice spiral CT（ MSCT ） examination. Methods Phantom measurement：the phantom scans were performed on the same location using doses 150,80,50,35,15mAs,and five same regions of interest were measured on every image. The homogeneity and noise level of CT were appraised. The patients＇ scans：40 children with lung infection were selected randomly,conventional -dose （150mAs） MSCT examinations were performed to detect the lesion and then the low- dose （50,35 and 15mAs） scans were performed on the focus. Their weighted CT dose index （CTDIw） and dose lenth product （DLP） were compared. The image quality was graded as excellent, good, acceptable and unacceptable by two experienced radiologists. Results The phantom measurement suggested that the lower the dose, the lower the homogeneity was. The lower the dose, the higher the noise level was. CTDIw was 10.0mGy,3.3 mGy,2.3 mGy and 1.0 mGy,respeetively,using 150 mAs,50 mAs,35 mAs and 15 mAs scanning protocol. Their DLPs was 117.8,39.3,27.5 and 11.8, respectively. 90% of image quality was acceptable on both lung and mediastinum windows acquired using doses of 150 mAs,50 mAs,35 mAs,while image quality was unacceptable on the mediastinum window when acquired using 15mAs. Conclusion It is recommended that the dose of 35 mAs is applicable for pediatric chest study without image quality compromises.

关 键 词：小儿 胸部 体层摄影术 X线摄影术 

分 类 号：R816.4[医药卫生—放射医学] R814.42[医药卫生—临床医学]