will have an entire series of points in 3 d whose gradient component will overlap near a common point at the center of the spiculation or nodule accordingly if the regions of potential overlap denoted generally as p x y z are accumulated into a cumulative array c u2032 the cumulative array c u2032 will contain higher values at locations corresponding to regions of possible abnormality the greater the number of overlapping regions or bins at an abnormality the greater the value of the cumulative array c u2032 in one embodiment of the present invention an edge of the nodule is represented by vector that estimates characteristics of the nodule such as size contrast sharpness and shape vector information obtained from various voxels can be aggregated to provide further details and characteristics of a nodule fig5 shows the general steps performed by a cad processing unit on digital images in accordance with the invention at step 502 images are either digitized or received in a digital format from a digital acquisition system the digital images may be for example a 3000 u00d7 4000 array of 12 bit gray scale pixel values fig5 shows the digital image being processed at step 504 by an overall nodule detection algorithm in accordance with the present invention the overall nodule detection algorithm performed at step 504 includes a stage for generating.