X-ray generating apparatus

• US 6,134,299 A
• Filed: 08/21/1998
• Issued: 10/17/2000
• Est. Priority Date: 08/29/1997
• Status: Expired due to Term

• Current Assignee: Varex Imaging Corporation
• Original Assignee: Varian Medical Systems Incorporated (Siemens AG)
• Inventors: Artig, Christopher F.
• Primary Examiner(s): Hajec, Donald
• Assistant Examiner(s): Felten, Daniel S.
• Application Number:
  US09/137,950
• Time in Patent Office: 788 Days
• Field of Search: 378/141, 378/125, 378/121, 378/127, 378/144, 378/203, 378/137
• US Class Current: 378/121
• CPC Class Codes: H01J 2235/1245 Increasing emissive surface area
• CPC Class Codes: H01J 2235/1262 Circulating fluids
• CPC Class Codes: H01J 2235/166 against electromagnetic radiation
• CPC Class Codes: H01J 35/10 Rotary anodes; Arrangements for rotating anodes; Cooling rotary anodes
• CPC Class Codes: H01J 35/106 Active cooling, e.g. fluid flow, heat pipes
• CPC Class Codes: H01J 35/16 Vessels; Containers; Shields associated therewith
• CPC Class Codes: H01J 35/18 Windows
• CPC Class Codes: H05G 1/025 Means for cooling the X-ray tube or the generator
• CPC Class Codes: H05G 1/04 Mounting the X-ray tube within a closed housing

Abstract

Air cooled x-ray generating apparatus is provided with a unitary vacuum enclosure having a rotating anode target and a cathode assembly for generating x-rays. The cathode assembly may be placed within the vacuum enclosure through an opening in the top wall thereof, and comprises a disk which completely covers this opening. The unitary vacuum enclosure and the disk form a radiation shield. A plurality of fins are disposed on the exterior side wall of the vacuum enclosure, and a shroud is attached to the fins to provide additional protection of ambient against radiation. The cathode assembly may be placed through a side wall of the vacuum enclosure. The additional protection against excessive radiation in this design is provided by a shielding member placed in proximity to the anode target. The shielding member extends from the side wall of the enclosure and is substantially parallel to the top wall.

Claims

1. An x-ray generating apparatus comprising:

a unitary vacuum enclosure comprising a top wall and a cylindrical side wall having a protruded inwardly shielding member, said shielding member being substantially parallel to said top wall and forming an upper and lower portions within said unitary vacuum enclosure, said top wall, cylindrical side wall and shielding member being made of materials capable to provide a required radiation shielding;

an anode assembly comprising a rotating anode target disposed within said lower portion of said unitary vacuum enclosure in proximity to said shielding member, said unitary vacuum enclosure having a thermal capacity that is substantially larger than a thermal capacity of said anode target; and

a cathode assembly spaced from said anode assembly and comprising an electron source disposed within said lower portion, and a mounting structure for holding said electron source disposed within said upper portion.

2. The x-ray generating apparatus of claim 1, wherein said cylindrical side wall comprises a first aperture within said upper portion of said unitary vacuum enclosure for protruding said cathode assembly therethrough.

3. The x-ray generating apparatus of claim 2, wherein said shielding member is made of a high-Z material.

4. The x-ray generating apparatus of claim 3, wherein said unitary vacuum enclosure further comprising a protective coating of a high-Z material deposited outside thereon, said unitary vacuum enclosure is made of material having the thermal expansion that is compatible with the thermal expansion of said protective coating.

5. The x-ray generating apparatus of claim 4, wherein said unitary vacuum enclosure is made of Iron based alloys with low thermal expansion such as Kovar.

6. The x-ray generating apparatus of claim 4, wherein said unitary vacuum enclosure is made of Copper.

7. The x-ray generating apparatus of claim 4, wherein said unitary vacuum enclosure is made of stainless steel.

8. The x-ray generating apparatus of claim 5, further comprising:

a mounting block which is attached to said cylindrical side wall, said mounting block has a port which is coupled to a second aperture in said cylindrical side wall within said lower portion of said unitary vacuum,

said first and second apertures are disposed at the opposite portions of said cylindrical wall, wherein generated x-rays are released through said second aperture.

9. The x-ray generating apparatus of claim 8, further comprising a high-voltage insulator protruded inwardly said upper portion of said unitary vacuum enclosure that is connected to said mounting structure of said cathode assembly.

10. The x-ray generating apparatus of claim 9, further comprising:

a plurality of fins disposed over an outer perimeter of said cylindrical side wall of said vacuum enclosure; and

a fan cooling device for producing flow of air through said plurality of fins for cooling of said walls of said unitary vacuum enclosure thereby directly transferring heat accumulated within said unitary enclosure directly to said plurality of fins.

11. An x-ray generating apparatus comprising:

a rotatable anode assembly having an anode target;

a cathode assembly spaced from said anode assembly and having an electron source for emitting a beam of electrons that strikes said anode target to generate x-rays

a unitary vacuum enclosure having a cylindrically shaped body with respective openings in a top and a side walls, a portion of said side wall being bent inwardly towards said electron source to create a space between said top wall and said portion of said side wall and to form a shroud over a substantial portion of said anode target so as to restrict off focus radiation generated thereof by secondary electrons; and

a high voltage insulator disposed within said space to vacuum seal said unitary vacuum enclosure, said high voltage insulator being connected to said cathode assembly.

12. The x-ray generating apparatus of claim 11, wherein said side and top walls of said unitary vacuum enclosure being made of a material capable of shielding the x-rays.

13. An x-ray generating apparatus comprising:

a unitary vacuum enclosure comprising a substantially cylindrical side wall and a top wall;

an anode assembly with a rotating anode target placed within said unitary cylindrical vacuum enclosure;

a cathode assembly spaced from said anode assembly and placed within said unitary vacuum enclosure, said cathode assembly comprising a disk protecting an aperture in said top wall and being substantially parallel to said anode target

a plurality of fins disposed over an outer perimeter of said cylindrical side wall; and

a shroud being attached to said plurality of fins and extending over said outer perimeter of said cylindrical side wall, and partially over said top wall,

wherein said unitary vacuum enclosure, said disk and said shroud being a shield for the x-rays and secondary electrons generated within said unitary vacuum enclosure.

14. The x-ray generating apparatus of claim 13, wherein an exterior surface of said unitary vacuum enclosure comprising a protective coating of a material having thermal expansion that is comparable to a thermal expansion of a material of said unitary vacuum enclosure.

15. The x-ray generating apparatus of claim 14, wherein said unitary vacuum enclosure is made of Kovar, and said protective coating is made of Tungsten or its alloys.

16. The x-ray generating apparatus of claim 15, wherein said plurality of fins is attached to said protective coating by brazing.