A method and system for generating synthetic scan images for use in a database of image-contour pairs, where the database is used in the delineation of features in one or more real scan images. The method comprises: providing real delineated scan images 502 acquired using a first image scanner； defining a model for the generation of a synthetic scan image using a second image scanner； processing the delineated image and mapping contours from the real image to form a new synthetic image-contour pair 505； repeating previous steps to generate a plurality of image-contour pairs； using the generated database to optimise an automated contouring algorithm 508； processing further real scan images using the optimised automated contouring algorithm. The second scan image may be acquired in real time. Operating parameters of the second image scanner may be based on distance between the source and the detector. The first scan image may be one of a CT, MRI or ultrasound (US) image. Processing may involve the use of a neural network or other machine learning techniques.
