The invention relates to a medical device operating with X rays comprising: an X ray source from which an X ray beam that has an intensity maximum along a central ray can be emitted a rotation unit with which the X ray source can be rotated about an isocentre wherein the central axis of the X ray beam is oriented eccentrically to the isocentre such that in particular upon rotation about the isocentre the central rays emitted from different spatial directions are tangential to an imaginary circle around the isocentre. Furthermore the invention relates to a method for operating a medical device comprising the following steps: providing an X ray source from which an X ray beam that has an intensity maximum along a central ray is emitted rotating the X ray source about an isocentre wherein the central axis of the X ray beam is oriented eccentrically to the isocentre such that in particular upon rotation about the isocentre the central rays emitted from different spatial directions are tangential to an imaginary circle around the isocentre.
