# US 8,542,801 B2 · X-ray tube with secondary discharge attenuation > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,542,801 B2 - Document ID: US8542801B2 - Status: Granted - Kind: B2 - Application number: 12/986,931 - Filed: 2011-01-07 - Published: 2012-07-12 - Granted: 2013-09-24 - Earliest claimed: 2011-01-07 - Assignees: General Electric Company - Applicants: Ethan James Westcot; Thomas Dean Schaefer; Kalyan Koppisetty - Inventors: Ethan James Westcot; Thomas Dean Schaefer; Kalyan Koppisetty - Web page: https://patentgrep.com/patent/US8542801B2 ## CPC - H01J 35/16: Vessels; Containers; Shields associated therewith - H01J 35/147: {Spot size control} - H01J 35/153: {Spot position control} - H01J 2235/166: against electromagnetic radiation - Y10T 29/49071: by winding or coiling - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract The present embodiments relate to off-focal X-ray radiation attenuation within X-ray tubes, for example X-ray tubes used in CT imaging. In one embodiment, an X-ray tube for off-focal X-ray radiation attenuation is provided. The X-ray tube includes a cathode, a target, and a magnetic focal spot control unit having at least one electromagnet encased in a resin loaded with X-ray attenuating material. ## Claims ### Claim 1 An X-ray tube, comprising: a cathode configured to output an electron beam; a target configured to receive the electron beam and to generate X-rays; magnetic focal spot control unit disposed between the cathode and the target and configured to generate electromagnetic fields to affect the electron beam, the magnetic focal spot control unit comprising at least one electromagnet encased in a resin loaded with an X-ray attenuating material. ### Claim 2 (depends on 1) The X-ray tube of claim 1, comprising an electron collector disposed in facing relation to the target and between the magnetic focal spot control unit and the target. ### Claim 3 (depends on 2) The X-ray tube of claim 2, wherein the magnetic focal spot control unit and the electron collector define a common bore through which the electron beam passes during operation. ### Claim 4 (depends on 3) The X-ray tube of claim 3, wherein the resin loaded with the X-ray attenuating material presents a thickness of at least approximately 9 mm through which X-rays must pass to exit the X-ray tube. ### Claim 5 (depends on 1) The X-ray tube of claim 1, wherein the X-ray attenuating material comprises a high-density, non-magnetic material. ### Claim 6 (depends on 1) The X-ray tube of claim 1, wherein the X-ray attenuating material comprises bismuth oxide. ### Claim 7 (depends on 6) The X-ray tube of claim 6, wherein the resin is doped with at least approximately 40% bismuth oxide by volume. ### Claim 8 (depends on 6) The X-ray tube of claim 6, wherein the resin is doped with at least approximately 50% bismuth oxide by volume. ### Claim 9 (depends on 1) The X-ray tube of claim 1, wherein the X-ray attenuating material comprises lead oxide. ### Claim 10 (depends on 1) The X-ray tube of claim 1, wherein the X-ray attenuating material comprises barium sulfate. ### Claim 11 (depends on 1) The X-ray tube of claim 1, wherein the magnetic focal spot control unit comprises a pair of substantially identical electromagnets. ### Claim 12 An electromagnet for an X-ray tube, comprising: an electromagnet assembly for a magnetic focal spot control unit configured to be disposed between a cathode and a target of an X-ray tube and configured to generate electromagnetic fields to affect the electron beam, the electromagnet being encased in a resin loaded with an X-ray attenuating material. ### Claim 13 (depends on 12) The electromagnet of claim 12, wherein the X-ray attenuating material comprises a high-density, non-magnetic material. ### Claim 14 (depends on 12) The electromagnet of claim 12, wherein the X-ray attenuating material comprises bismuth oxide, lead oxide, and/or barium sulfate. ### Claim 15 (depends on 12) The electromagnet of claim 12, wherein the resin is doped with at least approximately 40% bismuth oxide by volume. ### Claim 16 A method of forming an electromagnet, comprising: doping a resin with an X-ray attenuating material; winding a coil around a magnet core; and encasing the magnet core and the coil in the loaded resin. ### Claim 17 (depends on 16) The method of claim 16, wherein the X-ray attenuating material comprises a high-density, non-magnetic material. ### Claim 18 (depends on 17) The method of claim 17, wherein the X-ray attenuating material comprises bismuth oxide. ### Claim 19 (depends on 17) The method of claim 17, wherein the resin is doped with at least approximately 40% bismuth oxide by volume. ### Claim 20 (depends on 16) The method of claim 16, wherein the resin is doped with at least approximately 50% bismuth oxide by volume. ### Claim 21 (depends on 16) The method of claim 16, wherein the X-ray attenuating material comprises lead oxide. ### Claim 22 (depends on 16) The method of claim 16, wherein the X-ray attenuating material comprises barium sulfate. ### Claim 23 (depends on 16) The method of claim 16, wherein the magnet core and coil are encased in the loaded resin with a thickness of at least approximately 9 mm. ### Claim 24 (depends on 16) The method of claim 16, comprising adjusting the amount of attenuating material loaded into the resin based upon a desired level of X-ray attenuation. ### Claim 25 (depends on 16) The method of claim 16, comprising adjusting the amount of attenuating material loaded into the resin based upon a desired thickness of the resin.