The X-ray tube has a vacuum housing (26) rotatable about an axis (1). The ring shaped anode (5) is connected to the vacuum housing (26). The middle axis of the anode (5) corresponds to the axis of rotation (1) of the housing (26). A cathode (2) is arranged inside the housing (26) around the axis (1) of rotation. During operation of the X-ray tube, the cathode (2) emits electrons radially outwards. The X-ray tube also has an arrangement (10,11) to rotatably locate the vacuum housing (26). The housing (26) is rotated by a drive arrangement (16,17). A focusing arrangement focuses the electron beam (19) running from the cathode (2) to the anode (5). The electron beam (19) is focused such that it is incident on the anode at a fixed location focal spot (18).
