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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 investigate the effects of different deviations from the scan center on image quality and radiation dose of CT automated tube current modulation (ATCM) technique. Materials and Methods A 16-slice spiral CT fixed tube current and ATCM technique were used to scan the center of mass and the water mass of different eccentricities. Other collection parameters are the same. Record the size and CT value of the positioning image at different scanning positions, as well as the image’s mA and noise. Results As the distance between the water tube and the bulb increases, the positioning image is smaller but the CT value is unchanged. Fixed tube current scan, with the deviation from the isocenter distance increases, the more obvious image noise. The ATCM technique scans over 100 mm from the isocenter to 70 mm below the isocenter, which represents 168% to 78% of the isocenter and increases the image noise from 91% to 122%. Conclusion The application of ATCM technology to scan and deviate from the center of scanning field will significantly increase the image noise or radiation dose.