Abstract: The invention describes an X-ray source in which a cooling plate (36) for water-cooling the anode (28) of an X-ray tube (26) is firmly mounted on a radiation protection casing (20) and the X-ray tube (26) is rotatably borne relative to the cooling plate (36) in the radiation protection casing (20). The cooling plate (36) and X-ray tube (26) have small axial play with respect to each other, which allows for rotation. Radial seals (R1, R2) ensure adequate sealing of the cooling water throughout the entire axial play. Advantageously, a sealing plate (27) for adaptation to the cooling plate (36) is attached to the X-ray tube (25). With the X-ray source in accordance with the invention, it is easy to switch between various focus types in one casing structure.