1. A method for detecting polyps in a three dimensional (3D) image volume of an anatomical structure comprising the steps of: receiving a three dimensional (3D) image volume of an anatomical structure; obtaining a set of candidate locations in the image volume; for each candidate location, crop out three sub-volumes, wherein each sub-volume comprises a different scale and a plurality of voxels; for each of the three sub-volumes, obtain two additional sub-volumes (for a total of nine sub-volumes) at different orientations by rotating each sub-volume in two different directions; for each of the nine sub-volumes, apply a shape classifier thereto; discard voxels of each of the nine sub-volumes that are not identified by the shape classifier as being on a surface of a polyp, and for each voxel of each of the nine sub-volumes that is identified by the shape classifier as being on the surface of a polyp, perform the following: (a) compute a gradient direction for the voxel; (b) if the gradient direction for the voxel falls into one of a plurality of orientations, apply a probability classifier cascade to the voxel; (c) if the voxel passes the probability classifier cascade, its bounding box is remembered and its corresponding probability is outputted as a confidence measure therefor; and (d) repeat (a-c) for each remaining voxel of each of the nine sub-volumes; if bounding boxes exist after each of the nine sub-volumes has been analyzed, the candidate with the bounding box having the highest confidence measure is determined to be a polyp; and outputting the image volume with at least one polyp identified therein.