An X-ray source for emitting an X-ray beam is proposed. The X-ray source comprises an anode and an emitter arrangement comprising a cathode for emitting an electron beam towards the anode and an electron optics for focusing the electron beam at a focal spot on the anode. The X-ray source further comprises a controller configured to determine a switching action of the emitter arrangement and to actuate the emitter arrangement to perform the switching action, the switching action being associated with a change of at least one of a position of the focal spot on the anode, a size of the focal spot, and a shape of the focal spot. The controller is further configured to predict before the switching action is performed, based on the determined switching action, the size and the shape of the focal spot expected after the switching action. Further, the controller is configured to actuate the electron optics to compensate for a change of the size and the shape of the focal spot induced by the switching action.