Patent ID: 6426988
Filing Date: 2002-07-30
Classification: G06T,Y10S

Abstract:
An image processing method for obtaining a fault image by reconstructing image data obtained by an X-ray CT, comprising:an image-taking process for obtaining measured projection data by irradiating X-rays from a circumference of an object to be tested and detecting the X-rays passing through the object to be tested; a first image reconstructing process for reconstructing an initial image by subjecting the measured projection data obtained in said image-taking process to filtering and then backprojecting the filtered measured projection data; an estimated image setting process for setting an estimated image with a predetermined value; a high-absorber area setting process for setting a high-absorber area based on the initial image derived from the first image reconstructing process; an estimated projection data derivation process for deriving estimated projection data by forward projecting the estimated image in an X-ray irradiation direction; a comparison reference image deriving process for deriving a comparison reference image by backprojecting one of a difference and a ratio between the estimated projection data and the measured projection data; a weighting comparison reference image deriving process for deriving a weighted comparison reference image weighted such that as a path through which X-rays pass in the high-absorber area becomes longer, pixel values of the comparison reference image become smaller; an estimated image overwriting process for overwriting the estimated image by the weighted comparison reference image; an overwritten estimated projection data deriving process for deriving overwritten estimated projection data through the forward projection of the estimated image overwritten at the estimated image overwriting process; a measured projection data correction process for replacing the measured projection data at a portion where the X-rays pass through the high-absorber area with data according to the overwritten estimated projection data to correct the measured projection data; and a second image reconstructing process for reconstructing an image of the corrected measured projection data to derive the fault image.