"X-RAY APPARATUS FOR PRODUCING A 3D IMAGE FROM A SET OF 2D PROJECTIONS"

An X-ray apparatus has an X-ray examination system with an X-ray source and an X-ray detector which can be displaced relative to a subject for the pickup of 2D projections, an arrangement for determining extrinsic and intrinsic imaging parameters, and having a control and computing means stage for reconstructing 3D images from the 2D projections using the extrinsic and intrinsic imaging parameters. The arrangement for determining the intrinsic imaging parameters includes X-ray-positive marks which are allocated to the X-ray source and which are substantially in one plane and in the path of an X-ray beam emanating from the X-ray source.