Fig. 5.

Example of vessel segmentation at different scales. (a) CT volume after lung region extraction—only one slice is shown from demonstration, (b) output of the response function at scale corresponding to vessels of about 6 mm in diameter, (c) output of the response function at scale corresponding to vessels of about 14 mm in diameter, (d) and (e) segmentation of (b) and (c) using EM segmentation method, and (f) the vessel image after combining the segmentation results from all scales by the hierarchical integration scheme, the gray values, ranging from 0 to 12, indicate that the voxels were segmented at different scales that corresponded to different vessel sizes.