1. A method for three-dimensional imaging of a moving examination subject comprising the steps of: injecting a contrast agent into a subject, said contrast agent having a dwell time in an examination region of said subject; rotating an x-ray source, which emits an x-ray fan beam having a fan angle, and a radiation detector around said examination region at least once through 180° plus said fan angle during said dwell time, and thereby obtaining data representing a plurality of two-dimensional projections of said examination region; recording the geometric relations of said x-ray source, said radiation detector and said subject; and reconstructing a three-dimensional image from said data, whereby regarding said geometric relations.