The Processing of X-Ray Image Sequences

Abstract

Among the variety of image-processing applications, the analysis of x-ray data is of growing importance. In the past, study efforts concentrated mostly on the analysis of static pictures. Today, there is an increasing interest on the part of the physicians in extracting functional parameters from time-sequenced x-ray pictures (angiography). An angiographic analysis (e.g., of the kidney) proceeds as follows (see Fig. 1): The physician applies a radio-opaque contrast medium to the kidney to be examined. The contrast medium propagates through the kidney vessels at the speed of blood circulation. The resulting scene, which is of constant morphology but varying intensity, is viewed by the image intensifier video system of the x-ray equipment. Usually, the scene is assessed by estimating differences from image to image to get qualitative information about blood dynamics. Potentially, however, the sequence contains spatially very differentiated quantitative information about blood velocity or the filtration function of the kidney, which cannot be extracted in sequential viewing by eye. Thus, it is desirable to use image-processing tools to extract these parameters.