Discipline of Medical Radiation Sciences, Faculty of Health Sciences, University of Sydney, M Block PO Box 170, Lidcombe, NSW 1825, Australia.
Eur J Radiol. 2012 Jul;81(7):1514-9. doi: 10.1016/j.ejrad.2011.03.056. Epub 2011 Apr 9.
To provide a comparison between the image quality of electronically magnified (EM) and geometric, or true, magnification (TM) mammographic images.
One Computed Radiography (CR), one Digital Radiography (DR) and two screen-film (S-F) imaging systems were investigated. A Contrast-Detail Mammography (CDMAM) phantom was used as a test object. Three contact images and three sets of TM images with a magnification factor of 1.8 were taken on all systems. Software was used to zoom the contact images by a factor of 1.8 to produce EM images. Two observers evaluated all of the images. An Image Quality Figure and contrast detail curve were used to analyze the observer data and Mann-Whitney U-tests were performed to determine the statistical significance of the results.
No significant differences were found between soft copy and hard copy for any imaging modality. No significant difference in contrast detail detectability (CDD) was seen between EM images from the two digital systems and TM images on S-F systems. The results for the DR EM images and S-F TM images also showed no differences. The CDD of DR TM images was significantly better than both EM and S-F TM images.
Digitally zoomed images offer the same level of CDD as S-F TM images, and so may be viably used in their place. DR systems offer greater CDD than conventional S-F images, when comparing the TM images. This implies that doses can be greatly reduced for TM views using DR systems, while maintaining acceptable image quality.
比较电子放大（EM）和几何放大（TM）乳腺图像的质量。
研究了一个 Computed Radiography（CR）、一个 Digital Radiography（DR）和两个屏片（S-F）成像系统。使用 Contrast-Detail Mammography（CDMAM）体模作为测试对象。在所有系统上，均拍摄三张接触图像和三组放大系数为 1.8 的 TM 图像。使用软件将接触图像放大 1.8 倍生成 EM 图像。两位观察者评估所有图像。使用图像质量图和对比度细节曲线分析观察者数据，并进行 Mann-Whitney U 检验以确定结果的统计学意义。
对于任何成像方式，软拷贝和硬拷贝之间没有显著差异。在数字系统的 EM 图像和 S-F 系统的 TM 图像之间，对比度细节检测（CDD）没有显著差异。DR EM 图像和 S-F TM 图像的结果也没有差异。DR TM 图像的 CDD 明显优于 EM 和 S-F TM 图像。
数字缩放图像提供与 S-F TM 图像相同的 CDD，因此可以替代 S-F TM 图像使用。与传统的 S-F 图像相比，DR 系统在比较 TM 图像时提供更高的 CDD。这意味着使用 DR 系统进行 TM 视图时，可以大大降低剂量，同时保持可接受的图像质量。
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