An X-ray beam is generated in an interaction zone of an electron beam and a target, the zone being an annular layer of a molten fusible metal in an annular channel of a rotating anode assembly. The channel has a surface profile which prevents slopping of the molten metal in the radial direction and in both directions along the rotation axis. The liquid-metal target forms a circular cylindrical surface due to the centrifugal force acting thereupon. The linear velocity of the target is preferably higher than 80 m/s; in a vacuum chamber, a changeable membrane made of carbon nanotubes is installed in the X-ray beam path and a protective screen with apertures for electron beam entry and X-ray beam exit is arranged around the interaction zone. The technical result consists in an X-ray source with increased power, brightness, lifetime and ease of use.