管电流调制技术在上气道CT检查中的应用价值  

The Application of Tube Current Modulation Technique in CT Examination of Upper Respiratory Tract

作　　者：张永县[1] 张宗锐[1] 王淑芳[1] 康天良[1] 郭森林[1] 任悦[1] 牛延涛[1] 鲜军舫[1] 王振常[2] 

机构地区：[1]首都医科大学附属北京同仁医院放射科,北京100730 [2]首都医科大学附属北京友谊医院,100050

出　　处：《临床放射学杂志》2014年第11期1759-1763,共5页Journal of Clinical Radiology

基　　金：北京市卫生系统高层次卫生技术人才学科骨干基金资助项目(编号:2011-3-047)

摘　　要：目的探讨上气道CT检查中使用管电流调制技术降低辐射剂量的可行性。方法在管电流调制技术发展的三个阶段各选取33例成人上气道CT检查病例,共3组99例:常规剂量组,预设管电流量250 mAs;推荐剂量(Doseright)组,使用系统根据定位像和扫描范围推荐的有效mAs;Z轴管电流调制(Z-DOM)组,系统根据定位像在人体Z轴方向自动调节管电流。前两组扫描过程中m A保持不变,Z-DOM组mA改变;其他参数相同。用3mm层厚重组正中矢状面图像,测算对比噪声比(CNR);并用5分法对正中矢状面图像质量进行主观评价。对各组辐射剂量指标CT剂量指数(CTDI)、剂量长度乘积(DLP)和主客观评价指标进行统计学分析。结果三组的CTDI分别为:(14.70±0.00)m Gy、(16.50±2.59)m Gy、(4.60±1.99)m Gy,DLP分别为(465.87±31.55)m Gy·cm、(526.15±98.28)m Gy·cm、(147.74±67.08)m Gy·cm,辐射剂量差异有统计学意义(CTDI和DLP的F值分别为381.24和270.08,P<0.05),Doseright组的剂量高于常规剂量组10%,Z-DOM组明显低于前两组,分别为常规剂量组的30%、Doseright组的25%;三组CNR分别为523.91±80.75、540.28±117.65、511.09±107.56,差异无统计学意义(F=0.603,P=0.549>0.05);三组的主观评价指标分别为10.5(10,11.5)、11(10.5,11.5)、12.5(12.25,13.0),差异有统计学意义(χ2=48.373,P<0.05),两两比较Doseright组略高于常规剂量组(χ2=0.038,P>0.017),差异无统计学意义,Z-DOM组高于常规剂量组和Doseright组(χ2值分别为36.972和35.601,P<0.017),差异有统计学意义。结论上气道CT检查使用Z-DOM技术可有效降低辐射剂量,且保持较高的图像质量,可在临床实践中推广应用。Objective To investigate the feasibility of using tube current modulation technique to reduce the radiation dose in CT examination of upper respiratory tract.Methods A total of 99 adult patients were enrolled in this study.The patients were randomly and equally divided into three groups with 33 cases in each group.CT scanning of upper respiratory tract was performed in all patients.In the conventional dose group（ group A） the preset effective m As was 250 m As / slice,in the Doseright group（ group B） the recommended m As（ according to the surview and scanning range） was employed,while in the Z-DOM group（ Z axis tube current modulation,group C） the tube current was automatically adjusted by the system according to the positioning in the Z axis direction.During the scanning course the m A value was kept stable in group A and group B,while the m A value was changing in group C; the other parameters used in all three groups were the same.All the images were reconstructed by filtered back projection（ FBP） algorithm.The median sagittal images were reformatted with 3 mm thickness,and their corresponding contrast-to-noise ratios（ CNR） were calculated; the median sagittal images were subjectively evaluated by five division method（ subjective evaluation score）.The values of CTDI,CNR,DLP and subjective evaluation score of three groups were statistically analyzed.Results For group A,B and C,the CTDI was（ 14.70 ± 0.00） m Gy,（ 16.50 ± 2.59） m Gy and（ 4.60 ± 1.99） m Gy respectively; the DLP was（ 465.87 ± 31.55） m Gy·cm,（ 526.15 ± 98.28） m Gy·cm and（ 147.74 ± 67.08） m Gy·cm respectively; and the differences in radiation doses between each other among the three groups were statistically significant（ the F values of CTDI and DLP were 381.24 and381.24 respectively,P〈0.05）.The radiation dose of group B was 10% higher than that of group A,the dose of group C was significantly lower than that of group A and group B： about 70% lower than that of group B and 75% lower

关 键 词：上气道 CT 滤波反投影 辐射剂量 图像质量 综合评价法 

分 类 号：R816.4[医药卫生—放射医学]