The invention relates to an X-ray tube which includes a device for at least substantially protecting an object to be examined against the incidence of undesirable X-rays (E) which can be produced notably by the decay of a residual or surplus charge present in a high-voltage circuit after an X-ray exposure. To this end there is provided at least one device (341, 342) for deflecting and/or defocusing the electron beam (E) produced by the residual and/or surplus charge in such a manner that at least it is not incident to a significant extent on a region (22) of an anode (2) wherefrom X-rays excited thereby are directed towards an object to be examined.