2016 年 33 巻 4 号 p. 87-95
Digital phase-contrast-imaging（phase-imaging）using a small-focus X-ray tube provides images with greater sharpness than conventional X-ray imaging（conventional-imaging）, because the phase-imaging can produce images that are edge-enhanced at the boundary of an object because of refracted X-rays. In the present study, by performing image processing on a conventional-image we investigated whether we can produce an edge-enhanced conventional-image of equal edge-enhancement effect to that of phase-imaging. We used unsharp masking and Laplacian filtering as post-processing for edge enhancement of conventional-images. To determine the image processing parameters, the profile curves of acrylic fibers were used. Using these optimal imaging parameters, image processing was done on conventional-images of acrylic phantoms, followed by image quality comparisons of the post-processed conventional-images（post-processed-images）and phase-images. Furthermore, we performed a frequency analysis of the phase-image, conventional-image, and post-processedimage. Edge-enhanced conventional-images were obtained with a similar but slightly lower edge-enhancement effect than phase-images by processing images with appropriate parameters for unsharp masking and for Laplacian filtering. However,an increase in noise occurred because of the edge-enhancement processing. Edge-enhanced conventional-images of similar edge-enhancement effect to phase-images are obtainable by image processing of conventional-images. However, the edge clarity of the post-processed-images is somewhat worse than that of phase-images. Moreover, the edge-enhancement effect of post-processed-images is far lower than that of phase-images, because of increased noise resulting from the image processing.
