The watershed transformation on graphs for the segmentation of CT images

A segmentation method for computer tomography images using the concept of the watershed transformation on graphs in a hyperthermia planning environment is presented. First, the watershed transformation is applied on the gradient image. The resulting mosaic image is transformed into a graph and the watershed transformation is again performed on this graph. Solutions for the difficulties on graphs are presented. The iteration of this procedure leads to multiresolution segmentation planes showing regions that describe anatomical objects of different resolution at each plane. For some objects the selection of the adequate plane can be based on an object description. Since this is not possible for all objects, the segmentation planes are used as basis for an interactive segmentation environment. The user can select objects in different planes or merge regions to obtain an object.