A computer-implemented method of reconstructing boundaries from a computed tomography (CT) image dataset is provided. The method comprises receiving CT image data and applying a number of image filters to the CT image data. A numerical derivative is applied to the filtered CT image data to flatten and suppress non-edge regions that do not correspond to edges. Numerical derivative values are clipped to a specified range to reduce artifacts and noise, and an X-ray image is reconstructed according to the image filters and clipped numerical derivative values.