1. A method for modifying a target data set including a target object representative of a contour of an anatomical object, the method comprising: using a template data set comprising a modification template and an object template, wherein the modification template represents a first number of first areas or volumes to be added to the contour of the anatomical object and a second number of second areas or volumes to be subtracted from the contour of the anatomical object, matching the object template of the template data set to the target object of the target data set by an amending of the object template such that the object template of the template data set matches the target object representative of the contour of the anatomical object in the target data set, wherein the amending is also applied to the modification template to form an adapted modification template defining a modification; applying the modification defined by the adapted modification template to the target data set to modify the target object representative of the contour of the anatomical object in the target data set; and correcting a border between the target object and the adapted modification template to eliminate a disjunctive gap between the target object and the adapted modification template.