An improved x-ray tube that includes a plurality of cathodes in a region under vacuum is provided. Several wirelessly activatable elements, which are each assigned to a cathode or a group of cathodes, are arranged in the region under vacuum and make an electrically conducting connection of the cathode or the group of cathodes to a cathode control voltage line when receiving a control signal from outside of the region under vacuum. A system that includes the improved x-ray tube and several transmitter elements for the wireless activation of the wirelessly activatable elements is also provided.