1. A computer implemented method for automatic detection and segmentation of a target anatomical structure in received three dimensional (3D) volumetric medical images using a database of a set of volumetric images with expertly delineated anatomical structures, the method performed by the computer comprising the steps of: training a 3D anatomical structure detection and segmentation module offline by learning anatomical structure appearance using the set of expertly delineated anatomical structures; detecting online an anatomical structure of interest in a received volumetric image by defining a transformation between coordinates of said structure of interest and world coordinates; clustering said set of expertly delineated anatomical structures into a plurality of shape classes; selecting those features that best discriminate between the classes of shapes; and determining a shape of said structure of interest by computing a kernel weighted average over the expertly delineated anatomical structures, wherein said kernel is a function of selected feature values of the expertly delineated anatomical structures and the structure of interest; wherein said steps of training a 3D anatomical structure detection and segmentation module, detecting an anatomical structure of interest, clustering the expertly delineated anatomical structures, selecting features, and determining a shape are performed by a computer processor.