Integrated energy-sensitive and position-sensitive x-ray detection system

• US 5,500,534 A
• Filed: 03/31/1994
• Issued: 03/19/1996
• Est. Priority Date: 03/31/1994
• Status: Expired due to Term

• Current Assignee: Iowa State University Research Foundation Incorporated (Iowa State University)
• Original Assignee: Iowa State University Research Foundation Incorporated (Iowa State University)
• Inventors: Robinson, Douglas S., Jensen, Terrence C., Gray, Joseph N.
• Primary Examiner(s): Fields, Carolyn E.
• Assistant Examiner(s): Glick, Edward J.
• Application Number:
  US08/220,913
• Time in Patent Office: 719 Days
• Field of Search: 250/374, 250/385.1
• US Class Current: 250/385.1
• CPC Class Codes: G01T 1/185 with ionisation chamber arrangements
• CPC Class Codes: G01T 1/2935 using ionisation detectors
• CPC Class Codes: H01L 31/115 Devices sensitive to very short wavelength, e.g. X-rays, gamma-rays or corpuscular radiation

Abstract

An integrated x-ray detection system includes an x-ray detector fabricated on a wafer with a housing for containing a gas. The detector has a plurality of microstrip anodes and the housing passes x-rays which partially ionize the gas thereby producing a pulse at one of the anodes. The same wafer also has a plurality of integrated active signal processing circuits which are respectively coupled to the anodes. Each active signal processing circuit receives and processes pulses from respective ones of the anodes and outputs a digital signal indicating the location and energy of x-rays detected by the detector. An isolation layer separates the x-ray detector from the active signal processing circuits.

Claims

1. An integrated apparatus, comprising:

a wafer;

an x-ray detector fabricated on said wafer having a housing, a plurality of anodes and a gas contained in said housing, wherein at least a portion of said housing passes x-ray photons which partially ionize said gas thereby producing at least one pulse at one of said plurality of anodes;

a plurality of active signal processing circuits integrated into said wafer and respectively coupled to said plurality of anodes, wherein a respective one of said plurality of signal processing circuits receives and processes said at least one pulse to yield a digital signal indicating location of said one of said plurality of anodes and amplitude of said pulse; and

an electrically isolating layer for electrically isolating said x-ray detector from said plurality of active signal processing circuits.

2. The integrated x-ray detection system as claimed in claim 1, wherein said plurality of anodes comprise a plurality of microstrip anodes.

3. The integrated x-ray detection system as claimed in claim 2, further comprising a plurality of potential strips respectively interposed between said plurality of microstrip anodes.

4. The integrated x-ray detection system as claimed in claim 1, wherein said plurality of active signal processing circuits comprises a respective plurality of analog circuits coupled to said plurality of anodes and a respective plurality of digital circuits coupled to said plurality of analog circuits.

5. The integrated x-ray detection system as claimed in claim 4, wherein said plurality of analog circuits comprise:

a plurality of protection circuits respectively coupled to said plurality of anodes for receiving pulses from said plurality of anodes and for protecting electronic circuits downstream from said anodes;

a plurality of amplifiers respectively coupled to said plurality of protection circuits for receiving said pulses and amplifying said pulses to yield amplified pulses; and

a plurality of pulse shapers respectively coupled to said plurality of amplifiers for receiving said amplified pulses and outputting shaped pulses.

6. The integrated x-ray detection system as claimed in claim 5, wherein each of said respective plurality of digital circuits comprises:

a plurality of multiple energy window circuits each of said multiple energy window circuits respectively coupled to said plurality of pulse shapers for receiving said shaped pulses and outputting digital logic pulses when said shaped pulses have amplitudes within an externally selected range; and

a plurality of multiple digital counters respectively coupled to said plurality of multiple energy window circuits for receiving and counting said digital logic pulses.

7. The integrated x-ray detection system as claimed in claim 6, wherein each of said respective plurality of digital circuits further comprises:

an internal digital I/O bus coupled to said plurality of multiple digital counters for receiving data from said plurality of multiple digital counters; and

an I/O control logic device connected to said internal digital I/O bus for controlling said internal digital I/O bus.

8. The integrated x-ray detection system as claimed in claim 4, wherein each of said plurality of digital circuits comprises:

a plurality of digital counters for, receiving and counting signals received from a respective one of said plurality of analog circuits.

9. The integrated x-ray detection system as claimed in claim 4, wherein each of said plurality of analog circuits comprises a plurality of energy window circuits and each of said plurality of energy window circuits converts shaped pulses to logic pulses when said shaped pulses are within a corresponding voltage range.

10. The integrated x-ray detection system as claimed in claim 1, further comprising a metal shield layer between said plurality of active signal processing circuits and said x-ray detectors for shielding said plurality of active signal processing circuits from electrostatic fields and electro-magnetic radiation.

11. The integrated x-ray detection system as claimed in claim 10, wherein said electrically isolating layer has a plurality of vias and said metal shield layer has a corresponding further plurality of via surrounds for electrically connecting said plurality of anodes of said x-ray detector to said plurality of active signal processing circuits.

12. The integrated x-ray detection system as claimed in claim 10, further comprising a metal back potential plane between said metal shield layer and said x-ray detector for holding a potential applied to said metal back potential plane during operation to establish a control electrostatic field.

13. The integrated x-ray detection system as claimed in claim 1, further comprising a cathode plane mounted to said housing.

14. The integrated x-ray detection system as claimed in claim 1, further comprising:

an electrical feedthrough connected to said housing having a plurality of pins with at least a respective one of said plurality of pins electrically connected to a plurality of electrically connected potential strips alternately arranged between pairs of said plurality of anodes on said wafer to maintain said plurality of electrically connected potential strips at a first applied potential;

a metal shield layer between said plurality of active signal processing circuits and said x-ray detector for shielding said plurality of active signal processing circuits from electrostatic fields and electromagnetic radiation, with at least a respective one of said plurality of pins electrically connected to said metal shield layer to maintain said metal shield layer at a second applied potential

a metal back potential plane between said metal shield layer and said x-ray detector electrically connected to at least a respective one of said plurality of pins to maintain a third potential applied to said metal back potential plane during said x-ray detector operation to establish a control electrostatic field; and

electrical contacts to electrically connect at least a respective one of said plurality of pins to power, threshold, signal, and ground electrical connections of said plurality of active signal processing circuits.

15. The integrated x-ray detection system as claimed in claim 1, wherein said housing has an x-ray transparent window for allowing passage of said x-ray photons.

16. The integrated x-ray detection system as claimed in claim 1, wherein said housing has at least one of a plurality of pins electrically connected to said plurality of active signal processing circuits for conducting said digital signal.

17. An integrated x-ray detection system, comprising:

a wafer capable of supporting integrated circuitry;

a housing for housing said wafer and a gas, wherein at least a portion of said housing passes x-ray photons which partially ionize said gas thereby producing at least one electron;

a plurality of anodes fabricated on said wafer, said plurality of anodes being maintained at a first potential;

a plurality of potential strips alternately arranged among said plurality of anodes on said wafer and maintained at a second potential;

a cathode plane arranged along said wafer and maintained at a third potential;

a back potential plane fabricated on said wafer and maintained at a fourth potential, wherein said first, second, third and fourth potentials are selected such that said at least one electron is accelerated toward one of said plurality of anodes with sufficient energy to produce a pulse at said one of said plurality of anodes;

a plurality of active signal processing circuits integrated into said wafer and respectively coupled to said plurality of anodes wherein a respective one of said plurality of signal processing circuits receives and processes said pulse to yield a digital signal indicating location of said one of said plurality of anodes and height of said pulse; and

an insulating layer for separating said plurality of anodes, said plurality of potential strips and said back potential plane from said active signal processing circuit.

18. The integrated x-ray detection system as claimed in claim 17, wherein said plurality of anodes comprise a plurality of microstrip anodes.

19. The integrated x-ray detection system as claimed in claim 18, wherein said plurality of potential strips are respectively interposed between said plurality of microstrip anodes.

20. The integrated x-ray detection system as claimed in claim 17, wherein said plurality of active signal processing circuits comprises a respective plurality of analog circuits coupled to said plurality of anodes and a respective plurality of digital circuits coupled to said plurality of analog circuits.

21. The integrated x-ray detection system as claimed in claim 20, wherein said plurality of analog circuits comprise:

a plurality of protection circuits respectively coupled to said plurality of anodes for receiving pulses from said plurality of anodes and for protecting electronic circuits downstream from said anodes;

a plurality of amplifiers respectively coupled to said plurality of protection circuits for receiving said pulses and amplifying said pulses to yield amplified pulses;

a plurality of pulse shapers respectively coupled to said plurality of amplifiers for receiving said amplified pulses and outputting shaped pulses; and

a plurality of groups of energy window circuits respectively coupled to said plurality of pulse shapers for converting said shaped pulses to logic pulses when said shaped pulses are within a corresponding voltage range.

22. The integrated x-ray detection system as claimed in claim 21, wherein each of said plurality of digital circuits comprises:

a plurality of digital counters respectively coupled to said plurality of energy window circuits for receiving and counting said logic pulses.

23. The integrated x-ray detection system as claimed in claim 22, wherein each of said respective plurality of digital circuits further comprises:

an internal digital I/o bus coupled to said plurality of digital counters for receiving data from said plurality of digital counters; and

an I/O control logic device connected to said internal digital I/O bus for controlling said internal digital I/O bus.

24. The integrated x-ray detection system as claimed in claim 20, wherein each of said plurality of digital circuits comprises:

a plurality of digital counters for counting signals received from a respective one of said plurality of analog circuits.

25. The integrated x-ray detection system as claimed in claim 20, wherein each of said plurality of analog circuits comprises a plurality of energy window circuits and each of said plurality of energy window circuits converts shaped pulses to logic pulses when said shaped pulses are within a corresponding voltage range.

26. The integrated x-ray detection system as claimed in claim 17, wherein each of said plurality of active signal processing circuits comprises a plurality of amplifiers and a plurality of energy window circuits each having a corresponding voltage range, said plurality of energy window circuits being connected in parallel and each of said plurality of energy window circuits being coupled to each of said plurality of amplifiers for converting said pulse to a logic pulse when said pulse is within the corresponding voltage range.

27. The integrated x-ray detection system as claimed in claim 17, further comprising a metal shield layer between said plurality of active signal processing circuits and said plurality of anodes for shielding said plurality of active signal processing circuits from electrostatic fields and electro-magnetic radiation.

28. The integrated x-ray detection system as claimed in claim 27, wherein said insulation layer has a plurality of vias and said metal shield layer has a corresponding further plurality of via surrounds for electrically connecting said plurality of anodes to said plurality of active signal processing circuits.

29. The integrated x-ray detection system as claimed in claim 17, further comprising:

an electrical feedthrough connected to said housing having a plurality of pins with at least a respective one of said plurality of pins electrically connected to said plurality of electrically connected potential strips alternately arranged between pairs of said plurality of anodes on said wafer to maintain said plurality of electrically connected potential strips at a first applied potential;

a metal shield layer between said plurality of active signal processing circuits and said plurality of anodes for shielding said plurality of active signal processing circuits from electrostatic fields and electromagnetic radiation, with at least a respective one of said plurality of pins electrically connected to said metal shield layer to maintain said metal shield layer at a second applied potential;

wherein said back potential plane comprises a metal back potential plane between said metal shield layer and said plurality of anodes electrically connected to at least a respective one of said plurality of pins to maintain a third applied potential to said metal back potential plane during said x-ray detection system operation to establish a control electrostatic field; and

electrical contacts to electrically connect at least a respective one of said plurality of pins to power, threshold, signal, and ground electrical connections of said plurality of active signal processing circuits.

30. The integrated x-ray detection system as claimed in claim 17, wherein said housing has an x-ray transparent window for allowing passage of said x-ray photons.

31. The integrated x-ray detection system as claimed in claim 17, wherein said housing has at least one of a plurality of pins electrically connected to said plurality of active signal processing circuits for conducting said digital signal.