1. A method for surface contouring of a three-dimensional image of a subject, comprising the steps of: placing a first set of planes through the three-dimensional image; determining contours that are imaged in each of the planes of the first set of planes and that are associated with a surface contour of the three-dimensional image; and merging the contours determined in each plane of the first set of planes into a surface grid associated with the surface contour of the three-dimensional image.