1. A program storage device readable by a computer, tangibly embodying a program of instructions executable by the computer to perform method steps for detecting an object in a three-dimensional (3D) medical image, the method comprising the steps of: determining a region of interest (ROI) in the 3D medical image; determining a toboggan potential for each image element in the ROI; extracting a plurality of two-dimensional (2D) cutting planes from the ROI; and performing a tobogganing in the cutting planes to form a toboggan cluster to determine a location of the object, wherein image elements inside the toboggan cluster are stored in a cluster-member list, image elements on an outer-border of the toboggan cluster are stored in an outer-border list and image elements on an inner-border of the toboggan cluster are stored in an inner-border list wherein the step of tobogganing further comprises: (a) determining a concentration location, wherein if the concentration location is in the ROI, the tobogganing comprises: (b) adding the concentration location to the cluster-member list and adding neighbor image elements of the concentration location to an active-elements list; (c) selecting an image element with a minimum or maximum toboggan potential as a current image element; (d) determining a sliding direction of the current image element; (e) if the current image element slides to an image element in the cluster-member list, adding the current image element to the cluster-member list and adding neighbor image elements of the current image element to the active-elements list if the neighbor image elements of the current image element are not already in the active-elements list; (f) if the current image element does not slide to an image element in the cluster-member list, adding the current image element to the outer-border list and adding neighbor image elements of the current image element in the cluster-member list to the inner-border list; (g) repeating steps (c-f) until the active-elements list is empty, wherein the toboggan cluster includes image elements in the cluster-member list and inner-border list.