成像参数对多层螺旋CT自动管电流调制技术影响的实验研究  

Influences of imaging parameters on multi-slice CT with automatic tube current modulation:an experimerntal study

作　　者：张志伟[1] 罗天友[1] 欧阳羽[1] 曾勇明[1] 胡志华[1] 李信友[1] 陆云峰[1] 

机构地区：[1]重庆医科大学附属第一医院放射科,重庆400016

出　　处：《重庆医科大学学报》2012年第12期1097-1101,共5页Journal of Chongqing Medical University

基　　金：重庆市卫生局科研基金资助项目(编号:2008-2-29)

摘　　要：目的:探讨成像参数对多层螺旋CT自动管电流调制(Automatic tube current modulation,ATCM)技术图像质量及辐射剂量的影响。方法:使用16层螺旋CT ATCM技术扫描辐射等效仿真人体模。变换定位像采集参数:球管角度,管电流和管电压;变换螺旋扫描采集参数:噪声指数(Noise index,NI),螺距,探测器准直方式和管电压。比较不同成像参数下的管电流、容积CT剂量指数(Volume CT dose index,CTDIvol)和图像噪声。结果:90°侧位定位像比0°正位定位像的CTDIvol高28.45%。随着定位像的管电流和管电压的增加,CTDIvol有一定的降低。图像噪声随NI的增加而增大,CTDIvol随着NI的增加而减小。螺距、探测器准直和管电压变化时图像噪声基本保持不变。螺距=0.938时CTDIvol最大,当螺距从0.562增大到0.938时CTDIvol增加约6.44%;当螺距从0.938增大到1.375和1.750时,CTDIvol分别减少11.67%和23.05%。宽且厚的探测器准直方式,X线剂量利用效率高和辐射剂量低。随着管电压的升高,CTDIvol逐渐减小。结论:定位像参数必须标准化才能保证ATCM技术发挥其功效;合理选择成像参数才能保证图像质量的同时最大限度地降低辐射剂量。Objective：To explore the influences of imaging parameters on image quality and radiation dose in multi-slice CT with automatic tube current modulation（ATCM）.Methods：An equivalent anthropomorphic phantom was scanned using a 16-slice multi-slice spiral CT with ATCM.ATCM was studied with variable positioned image acquisition parameters（tube angle,tube current,tube voltage）and spiral scan acquisition parameters[noise index（NI）,pitch,detector collimation configuration and tube voltage].Changes in tube turlent,volume CT dose index（CTDIvol）and image noise resulting from the modulation were calculated and compared.Results： Value of CTDIvol from the position angle of 90° was 28.45% higher than that from the position angle of 0°.Value of CTDIvol was decreased when tube current and tube voltage were increased for positioned image.Image noise was increased and value of CTDIvol was decreased alongside the growth of the NI.Image noise was remained in constant in spite of changes of pitch,detector collimation or tube voltage.Value of CTDIvol came to the peak at pitch of 0.938.Value of CTDIvol was increased by 6.44% when pitch changed from 0.562 to 0.938 and was decreased respectively by 11.67% and 23.05% when pitch changed from 0.938 to 1.375 and 1.75.Wider and thicker detector collimation configuration had higher X-ray dose utilization ratio and lower radiation dose.Value of CTDIvol was decreased when the tube voltage was increased.Conclusions：Positioned image acquisition parameters must be standardized to ensure that ATCM technique can exert effects normally.Imaging parameters should be selected rationally to guarantee that ATCM technique can control the image quality well and reduce the radiation dose.

关 键 词：多层螺旋CT 自动管电流调制技术 仿真人体模 成像参数 

分 类 号：R814.42[医药卫生—影像医学与核医学]