Andoh K, Odagiri K, Matsumoto T, Yamashita K, Ogino I, Otsuka T
Department of Radiology, Kanagawa Cancer Center, Yokohama, Japan.
J Digit Imaging. 1997 Aug;10(3):132-6. doi: 10.1007/BF03168601.
The purpose of this study is to determine whether the computed radiography system sensitivity value can be used as an image quality indicator for computed radiography excretory urography with radiation dose reduction. One hundred and twenty-four patients with gynecological malignancies were studied prospectively. Five-minute and 10-minute computed radiographic images of excretory urography were obtained in each patient with different radiation doses (ie, a standard dose image required with screen-film method and a reduced dose one). The images were subjectivity scored by three radiologists without knowledge of the exposure factors or the system sensitivity values. The quality scores of the reduced-dose images used in the five steps were compared with those of the standard dose images (the system sensitivity value was 80 to 120). The images with reduced exposures were arbitrarily divided into five steps according to the system sensitivity value (ie, 150 to 250, 260-400, 410-600, 610-1000, and 1010-1500). There was a gradual degradation of the image quality as the system sensitivity value was increased. In terms of visualization of the bones, the images taken with the system sensitivity values of 150-250 (40%-67% of the standard dose system) showed no statistically significant difference from the standard dose images. As for visualization of the renal pelvic margins, the images taken with the system sensitivity values of 260 to 400 (2%-38% of the standard dose system) showed no statistically significant difference. We conclude that system sensitivity value can be used as a practical though approximate indicator of the image quality.
本研究的目的是确定计算机X线摄影系统灵敏度值是否可用作计算机X线摄影排泄性尿路造影降低辐射剂量时的图像质量指标。对124例妇科恶性肿瘤患者进行了前瞻性研究。对每位患者分别以不同辐射剂量（即屏-片法所需的标准剂量图像和降低剂量图像）获取排泄性尿路造影的5分钟和10分钟计算机X线摄影图像。由三位放射科医生在不了解曝光因素或系统灵敏度值的情况下对图像进行主观评分。比较了五个步骤中使用的低剂量图像与标准剂量图像（系统灵敏度值为80至120）的质量分数。根据系统灵敏度值（即150至250、260 - 400、410 - 600、610 - 1000和1010 - 1500）将低曝光图像任意分为五个步骤。随着系统灵敏度值增加，图像质量逐渐下降。在骨骼显示方面，系统灵敏度值为150 - 250（标准剂量系统的40% - 67%）时拍摄的图像与标准剂量图像相比无统计学显著差异。至于肾盂边缘的显示，系统灵敏度值为260至400（标准剂量系统的2% - 38%）时拍摄的图像无统计学显著差异。我们得出结论，系统灵敏度值可作为图像质量的一个实用但近似的指标。
