First projection images are recorded. The first projection images map an examination object along different first projection directions. A corresponding respective second projection image is recorded for at least two first projection images. The first projection images each have a first focus point, and the second projection images each have a second focus point. Each of the second projection images together with a corresponding first projection image at least partially map a common part of the examination object about a stationary center point. The second projection images map the examination object along second projection directions that are mutually different and at least partially different, relative to the respectively corresponding first projection directions such that a straight line through the first focus point and the second focus point of the mutually corresponding first projection images and second projection images extends through the stationary center point. The 3D image dataset is reconstructed.