An apparatus (210) and method for total or partial blanking of an electron beam (e) during a jump between the 2 or more positions of a dynamic focal spot (FP) movement in circumferential direction of the electron beam impinging on the focal track (FPTR) of a rotating target disk (230) of a X-ray tube (110). Alternatively the focal spot size can be increased during this short time interval. Overheating of the anode at the focal spot can be prevented.