Multiple target anode assembly and system of operation

• US 7,065,179 B2
• Filed: 11/07/2003
• Issued: 06/20/2006
• Est. Priority Date: 11/07/2003
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Chabin, Eric, Block, Wayne F., Sridhar, Gorur N., Price, J. Scott, Hsieh, Jiang
• Primary Examiner(s): Glick, Edward J.
• Assistant Examiner(s): Kiknadze, Irakli
• Application Number:
  US10/605,943
• Publication Number:
  US 20050100132A1
• Time in Patent Office: 956 Days
• Field of Search: 378/4, 378/9, 378/19, 378/20, 378/57, 378/119, 378/113, 378/124, 378/125, 378/134, 378/136, 378/143, 378/144, 378/146, 378/5, 378115-118
• US Class Current: 378/134
• CPC Class Codes: H01J 2235/068 Multi-cathode assembly
• CPC Class Codes: H01J 35/10 Rotary anodes; Arrangements for rotating anodes; Cooling rotary anodes

Abstract

An anode assembly having multiple target electrodes is disclosed. Each target electrode produces an x-ray fan beam for radiographic data acquisition. The target electrodes are designed to sequentially generate an x-ray fan beam and therefore operate at a proportional duty cycle per scan. Power output capabilities of the anode assembly is increased without an increase in the size or thermal overloading of the anode assembly.

Claims

1. An x-ray tube assembly comprising:

a plurality of independently controllable electron sources configured to emit electrons;

an anode disc;

a plurality of target electrodes disposed on the anode disc and configured to receive electrons emitted by the plurality of independently controllable electron sources and emit a plurality of fan beams of radiographic energy in response thereto;

a thermal feedback loop operably connected to provide feedback indicative of thermal conditions of at least one target electrode; and

an electron firing controller operably connected to the thermal feedback loop and configured to selectively fire the plurality of independently controllable electron sources to maintain a thermal load on the at least one target electrode below a given threshold.

2. The assembly of claim 1 wherein the thermal feedback loop provides feedback indicative of a thermal load on each target electrode and wherein the controller is configured to disable an electron source corresponding to a given target electrode if the thermal load of the given target electrode exceeds the given threshold.

3. The assembly of claim 1 wherein the thermal feedback loop provides feedback regarding a firing duration of the at least one target electrode and wherein the controller is configured to determine a temperature of the at least one target electrode from the firing duration.

4. The assembly of claim 1 wherein the controller is configured to determine a thermal stress on the at least one target electrode in near real-time.

5. The assembly of claim 1 wherein the controller is configured to fire each of the plurality of independently controllable electron sources in a sequential manner before re-firing of an electron source if no target electrode is under an unacceptable thermal stress.

6. The assembly of claim 1 wherein the plurality of independently controllable electron sources includes a first target electrode at a first radial distance from a center of the anode disc to produce a first spatial coverage and a second target electrode at a second radial distance from the center of the anode disc that is different than the first radial distance to produce a second spatial coverage that is substantially similar to the first spatial coverage.

7. The assembly of claim 1 wherein the plurality of target electrodes is oriented with respect to one another such that each fan beam has a similar spatial coverage.

8. The assembly of claim 1 wherein each fan beam extends along a z-axis.

9. The assembly of claim 1 wherein the plurality of electron sources includes a plurality of tungsten targets integrated in a beveled portion of the anode disc.

10. A CT system comprising:

a rotatable gantry having a bore centrally disposed therein;

a table movable fore and aft through the bore and configured to position a subject for CT data acquisition;

a detector array disposed within the rotatable gantry and configured to detect x-radiation attenuated by the subject;

an anode disc positioned within the rotatable gantry;

multiple x-ray sources extending circumferentially about the anode disc and configured to project x-ray fan beams toward the subject; and

a controller operably connected to the multiple x-ray sources and configured to selectively fire the multiple x-ray sources based on respective thermal stresses on the multiple x-ray sources;

wherein the controller determines the respective thermal stresses on the multiple x-ray sources.

11. The CT system of claim 10 wherein each x-ray source includes a tungsten electrode that generates an x-ray fan beam when bombarded with electrons from an electron source, and the controller operably connected to receive thermal feedback of each tungsten electrode to determine a thermal stress of each tungsten electrode.

12. The CT system of claim 11 wherein the controller causes x-ray emission of each tungsten electrode based on a proportional duty cycle if no tungsten electrode is under an unacceptable thermal stress.

13. The CT system of claim 12 wherein each tungsten electrode has a respective electron source, and wherein the controller disables a given electron source as long as the corresponding tungsten electrode is under an unacceptable thermal stress.

14. The CT system of claim 10 wherein the multiple x-ray sources includes:

a rotatable anode disc having a beveled face;

a first tungsten electrode track disposed on the beveled face and extending circumferentially about the disc at a first radius; and

a second tungsten electrode track disposed on the beveled face and extending circumferentially about the disc at a second, different from the first, radius.