1. A method for automatically localizing a predetermined number M of fiducial markers in at least one image volume, comprising steps of: determining an intensity threshold value based on said at least one image volume; modifying said at least one image volume by separating voxels of said image volume into foreground and background voxels based on said intensity threshold value; searching the modified at least one image volume for foreground voxels which may lie within candidate markers by grouping foreground voxels having similar intensities proximate to each other; determining candidate voxels which may be included in voxels corresponding to candidate markers of said at least one image volume corresponding to fiducial markers; and examining a region in the at least one image volume around each of the candidate voxels and determining which of said candidate voxels most likely correspond to a portion of said fiducial markers in said at least one image volume.