Patent ID: 6339635
Filing Date: 2002-01-15
Classification: H01J

Abstract:
An x-ray tube comprising:a vacuum housing; a cathode disposed in said vacuum housing, said cathode emitting electrons; a circular anode plate in said vacuum housing, said circular anode plate having an annular target surface thereon; a quadrupole magnet system which emits a magnetic field which interacts with said electrons for focusing and deflecting said electrons to a focal spot on said annular target surface of said circular anode plate, said quadrupole magnet system comprising a plurality of coils respectively operated by a plurality of coil currents; and a control unit connected to said plurality of coils and supplying said plurality of coil currents respectively to said plurality of coils, said control unit having stored therein a plurality of parameter sets for respectively setting different values for the respective coil currents, said control unit activating a selected parameter set to azimuthally displace said focal spot from a first location to a predetermined, second location spaced from said first location on said annular target surface of said circular anode plate.