McCollough C H, Bruesewitz M R, Vrtiska T J, King B F, LeRoy A J, Quam J P, Hattery R R
Department of Radiology, E2-A, Mayo Clinic and Foundation, 200 First St SW, Rochester, MN 55905, USA.
Radiology. 2001 Nov;221(2):395-403. doi: 10.1148/radiol.2212000784.
To evaluate image quality and dose for abdominal imaging techniques that could be used as part of a computed tomographic (CT) urographic examination: screen-film (S-F) radiography or computed radiography (CR), performed with moving and stationary grids, and CT scanned projection radiography (CT SPR).
An image quality phantom underwent imaging with moving and stationary grids with both a clinical S-F combination and CR plate. CT SPR was performed with six CT scanners at various milliampere second and kilovolt peak settings. Entrance skin exposure (ESE); spatial, contrast, and temporal resolutions; geometric accuracy; and artifacts were assessed.
S-F or CR images, with either grid, provided image quality equivalent to that with the clinical standard, S-F with a moving grid. ESE values for both S-F and CR were 435 mR (112.2 microC/kg [1 mR = 0.258 microC/kg]) with a moving grid and 226 mR (58.3 microC/kg) with a stationary grid. All CT SPR images provided inferior spatial resolution compared with S-F or CR images. High-contrast objects generated substantial artifacts on CT SPR images. Compared with S-F, CR and CT SPR provided improved resolution of small low-contrast objects. The contrast between iodine and soft-tissue-mimicking structures on CT SPR images acquired at 80 kVp was twice that at 120 kVp. CT SPR images with acceptable noise levels required a midline ESE value of approximately 300 mR (77.4 microC/kg) at 80 kVp.
S-F and CR provided better spatial resolution than did CT SPR. However, CT SPR provided improved low-contrast resolution compared with S-F, at exposures comparable to those used for S-F or CR.
评估可作为计算机断层扫描（CT）尿路造影检查一部分的腹部成像技术的图像质量和剂量：使用移动和固定滤线栅的屏-片（S-F）摄影或计算机X线摄影（CR），以及CT扫描投影摄影（CT SPR）。
使用临床S-F组合和CR板，对图像质量模体进行移动和固定滤线栅成像。使用六台CT扫描仪在不同的毫安秒和千伏峰值设置下进行CT SPR。评估了体表入射剂量（ESE）、空间分辨率、对比度分辨率、时间分辨率、几何精度和伪影。
使用任一滤线栅的S-F或CR图像的图像质量与临床标准（使用移动滤线栅的S-F）相当。使用移动滤线栅时，S-F和CR的ESE值均为435 mR（112.2 μC/kg [1 mR = 0.258 μC/kg]），使用固定滤线栅时为226 mR（58.3 μC/kg）。与S-F或CR图像相比，所有CT SPR图像的空间分辨率均较差。高对比度物体在CT SPR图像上产生大量伪影。与S-F相比，CR和CT SPR对小的低对比度物体的分辨率有所提高。在80 kVp下采集的CT SPR图像上，碘与软组织模拟结构之间的对比度是120 kVp下的两倍。具有可接受噪声水平的CT SPR图像在80 kVp时中线ESE值约为300 mR（77.4 μC/kg）。
S-F和CR的空间分辨率优于CT SPR。然而，在与S-F或CR相当的曝光条件下，CT SPR与S-F相比，低对比度分辨率有所提高。
