偏离等中心点对CT自动管电流调制技术图像质量及辐射剂量的影响  

The Influence of Off-centering on CT Image Quality and Dose Using Automatic Tube Current Modulation Technique

作　　者：张志伟[1] 罗天友[1] 曾勇明[1] 唐艳隆[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,400016

出　　处：《临床放射学杂志》2010年第5期677-679,共3页Journal of Clinical Radiology

基　　金：重庆市卫生局科研基金资助项目(基金编号2008-2-29)

摘　　要：目的探讨偏离扫描野等中心点对CT自动管电流调制(ATCM)技术图像质量及辐射剂量的影响。资料与方法使用16层螺旋CT固定管电流和ATCM技术扫描等中心点及不同偏心位置的质量保证水模。其他采集参数保持一致。记录不同扫描位置定位像的大小和CT值,以及图像的mA和噪声。结果随着水模偏离球管的距离增加,定位像越小,但CT值无改变。固定管电流扫描,随着偏离等中心点距离的增加,图像噪声越明显。ATCM技术扫描,等中心点以上100mm到等中心点以下70mm,管电流是等中心点的168%到78%,图像噪声从91%增加到122%。结论应用ATCM技术扫描,偏离扫描野等中心点将显著增加图像噪声或辐射剂量。Objective To evaluate the influence of off-center on CT dose and image quality using automatic tube current modulation（ATCM） technique. Materials and Methods An quality assurance water phantom was scanned in iso-center and various off-center positions using a 16-slice spiral CT with fixed-tube current and with ATCM technique. The size and CT value of the frontal localizer radiographs,mA and noise in the images were recorded after scanning. Resu-lts The size of the frontal localizer radiographs became smaller with the increase of distance from the tube but without significant difference. In fixed-tube current scanning,the noise increased with distance apart from the iso-center. With ATCM technique,from 100 mm above to 70 mm below the gantry iso-center,the tube current products ranged from 168% to 78%,and image noise ranged from 91% to 122% compared with those at the gantry iso-center. Conclusion With ATCM technique,off-centering may increase the image noise or radiation dose sharply.

关 键 词：体层摄影术 X线计算机 等中心点 自动管电流调制技术 辐射剂量 

分 类 号：R144[医药卫生—公共卫生与预防医学]