1. A system for segmenting current diagnostic images comprising: one or more workstations which segment a volume of interest in previously generated diagnostic images of a selected volume of interest generated from a plurality of patients; one or more processors programmed to: register the segmented previously generated images, and merge the segmented previously generated images into a probability map which depicts a probability that each voxel represents the volume of interest, a probability that each voxel represents background, and a mean segmentation boundary; a segmentation processor which registers the probability map with a current diagnostic image of the volume of interest in a current patient to generate a transformed probability map, the segmentation processor being programmed to register the probability map with the current image by performing the steps of: registering the mean segmentation boundary to the volume of interest of one of the current image and a model registered to the current image; determining a transform by which the mean segmentation boundary was transformed to be registered to the current image or model; transforming the probability map with the determined transform to generate the transformed probability map; and a segmentation boundary processor which determines a segmentation boundary for the volume of interest based on the transformed probability map.