X-ray detector for feedback stabilization of an X-ray tube
View Patent ↗An x-ray tube emits X-rays in response to a current control signal. An X-ray detector detects the emitted X-rays and provides a detected X-ray signal indicative thereof to a control system, which provides the current control signal. The X-ray detector provides feedback stabilization of the X-ray output from a source of X-rays, such as, for example an X-ray tube. The detector produces an electrical signal proportional to the X-ray output of the X-ray tube, and that signal is used to control the electron beam current in the tube in order to stabilize the X-ray output of the tube at a predetermined value.
1. A system for controlling the X-ray output of an X-ray tube, said system comprising:
an X-ray tube that emits an X-ray output in response to a control signal;
an X-ray transmissive X-ray detector through which at least a portion of said X-ray output passes that detects X-rays emitted from said X-ray tube, and provides a detected X-ray signal indicative of a property of the X-rays that are emitted by the X-ray tube; and
a control system that receives said detected X-ray signal and provides said control signal responsive to changes in conditions within said X-ray tube to ensure that said X-ray output is substantially maintained at a predetermined value.
2. The system as claimed in claim 1 , wherein said changes in conditions within the X-ray tube include changes in leakage currents within the X-ray tube.
3. The system as claimed in claim 1 , wherein said changes in conditions within the X-ray tube include changes any of the size, shape or location of a focal spot of electrons on an anode within the X-ray tube.
4. The system as claimed in claim 1 , wherein said detected X-ray signal is maintained at a substantially constant value by said control system.
5. The system as claimed in claim 1 , wherein said property of the X-rays that are emitted by the X-ray tube is the intensity of the X-rays that are emitted from the X-ray tube.
6. The system as claimed in claim 1 , wherein said X-ray tube comprises an X-ray window through which the X-rays pass, and said X-ray detector is positioned adjacent to said X-ray window.
7. The system as claimed in claim 6 , wherein said X-ray detector partially covers said X-ray window.
8. The system as claimed in claim 6 , wherein said X-ray detector completely covers said X-ray window.
9. The system as claimed in claim 6 , wherein substantially all of said X-ray output that passes through the X-ray window inpinges on the X-ray transmissive X-ray detector.
10. The system as claimed in claim 6 , wherein said system further includes an X-ray anode that is positioned near the X-ray window.
11. The system as claimed in claim 6 , wherein said X-ray window comprises an X-ray transmissive anode.
12. The system as claimed in claim 6 , wherein said system further includes a filter and wherein substantially all of said X-ray output that passes through the X-ray window impinges on the filter.
13. The system as claimed in claim 1 , wherein said X-ray detector provides a filter function.
14. The system as claimed in claim 1 , wherein said X-ray detector is configured and arranged as a segmented detector that includes a plurality of detector elements.
15. The system as claimed in claim 14 , wherein at least one of said detector elements includes a filter.
16. The system as claimed in claim 14 , wherein said property of the X-rays is provided by a ration of detected X-ray signals from at least two of said detector elements.
17. The system as claimed in claim 1 , wherein said X-ray tube includes an X-ray producing target and said X-ray detector is positioned substantially close to said X-ray producing target.
18. The system as claimed in claim 1 , wherein said control signal is a current control signal.
19. The system as claimed in claim 18 , wherein said current control signal controls the temperature of a cathode in the X-ray tube.
20. The system as claimed in claim 1 , wherein said X-ray detector comprises at least one of a photodiode, a pin diode, an ionization detector, a scintillation detector, an electron multiplier, and a charge-coupled device.
21. The system as claimed in claim 1 , wherein said system is included within a battery powered device.
22. The system as claimed in claim 1 , wherein said system is included in a hand-held device.
23. The system as claimed in claim 1 , wherein said system is configured for use as an X-ray fluorescence analytical instrument.
24. A system for controlling the X-ray output of an X-ray tube, said system comprising:
an X-ray tube that emits an X-ray output through a window in response to a control signal;
an X-ray detector that is on said window and on which at least some of the X-ray output impinges, said X-ray detector providing a detected X-ray signal indicative of a property of the X-rays that are emitted by the X-ray tube through the window; and
a control system that receives said detected X-ray signal and adjusts said control signal responsive to changes in conditions within said X-ray tube to ensure that said X-ray output is substantially maintained at a predetermined value.
25. The system as claimed in claim 24 , wherein said changes in conditions within the X-ray tube include changes in leakage currents within the X-ray tube.
26. The system as claimed in claim 24 , wherein said changes in conditions within the X-ray tube include changes in any of the size, shape or location of electrons on an anode within the X-ray tube.
27. The method of controlling the X-ray output of an X-ray tube, said method comprising the steps of:
providing an X-ray tube that emits an X-ray output in response to a control signal;
providing an X-ray transmissive X-ray detector through which at least a portion of said X-ray output passes that detects X-ray emitted from said X-ray tube,
providing a detected X-ray signal indicative of a property of the X-rays that are emitted by the X-ray tube; and
adjusting said control signal reponsive to changes in conditions within the X-ray tube to ensure that said detected X-ray signal is substantially maintained at a predetermined value.
28. The method as claimed in claim 27 , wherein said X-ray tube includes an X-ray output window and said X-ray detector is positioned substantially close to said X-ray window.
29. The method as claimed in claim 27 , wherein substantially all of said X-ray output from the window impinges on said X-ray detector.
30. The method as claimed in claim 27 , wherein said X-ray tube includes an X-ray producing target and said X-ray detector is positioned substantially close to said X-ray producing target.
31. The method of controlling the X-ray output of an X-ray tube, said method comprising the steps of:
providing an X-ray tube that emits an X-ray ouput through a window in response to a control signal;
providing an X-ray detector that on the window and on which at least a portion of said X-ray output impinges,
providing a detected X-ray signal indicative of a property of the X-ray that are emitted by the X-ray tube; and
adjusting said control signal responsive to changes in conditions within the X-ray tube to insure that said detected X-ray signal is substantially maintained at a predetermined value.
32. The method as claimed in claim 31 , wherein said X-ray detector is transmissive.
33. The method as claimed in claim 31 , wherein said X-ray tube includes an X-ray producing target and said X-ray detector is positioned substatially close to said X-ray producing target.