26 May 1999 Enhanced latitude for digital projection radiography
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The trade-off between contrast and latitude is a well-known and long-standing image quality limitation in projection radiography. With the introduction of electronic acquisition, it is possible to capture a wide range of x-ray exposures in a single image. However, the problem of rendering and displaying images, such that information outside the normal expected latitude is visualized while maintaining adequate contrast for diagnostic details, has remained. The enhanced visualization processing (EVP) algorithm described in this paper addresses this problem. A clinical study is reported utilizing 70 images, including 5 images of each of 14 examination types selected from a large data base of diagnostic computed radiography images. For each image, a control rendering was produced by means of a state-of-the-art automated tone scaling algorithm. A test rendering was produced by applying EVP to the control image. Ten radiologists independently rated the 140 resulting images on a 9-point diagnostic quality scale. EVP provided increased exposure latitude without objectionable loss of detail contrast. In many images, EVP substantially reduced the loss of information in normally under-penetrated areas, while reducing the need for 'bright lighting' in over- penetrated areas. The diagnostic quality ratings of both EVP and control images were, on average, high. However, the median rating for EVP images was one full rating category higher than that of the control images. Viewing the images as pairs, 76 percent of the EVP images were rated 1 or more categories superior to the corresponding control image while only 6 percent of the control images were rated as superior to the corresponding EVP image. Similar results were obtained across all 14 examination-types studied.
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Richard L. Van Metter, Richard L. Van Metter, David H. Foos, David H. Foos, } "Enhanced latitude for digital projection radiography", Proc. SPIE 3658, Medical Imaging 1999: Image Display, (26 May 1999); doi: 10.1117/12.349459; https://doi.org/10.1117/12.349459

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