1. An x-ray system comprising: a radiographic image acquisition unit that acquires a plurality of radiographic images of a subject; an optical image acquisition unit that acquires a plurality of optical images of the examination subject that are respectively congruent to said x-ray images, said subject having markers applied thereto during acquisition of said radiographic images and during acquisition of said optical images, said markers being visible in each of said optical images and said radiographic images; an image processor that detects respective positions of said markers in each of said optical images and said radiographic images and that is configured to calculate a transformation matrix dependent on the respective positions of the markers in the respective optical images and the respective radiographic images; and said image processor being configured to compose an aggregate image of said x-ray images using said transformation matrix to convert an image content of a first of the radiographic images into a coordinate system of a second of the radiographic images to combine said first of said radiographic images with said second of said radiographic images with the same coordinate system in said aggregate image.