1. A method for segmenting a three-dimensional image data set, comprising the following steps: a) providing a three-dimensional image data set of a body structure, which is to be segmented, and a generic model of the body structure; b) generating synthetic two-dimensional image data sets on the basis of the three-dimensional image data set of the body structure provided in a); and c) pre-positioning the generic model in relation to the three-dimensional image data set of the body structure provided in a); and e) generating a three-dimensional model of the body structure by fitting the generic model to the synthetic two-dimensional image data sets of the body structure, generated in step b).