DETECTOR AND METHOD OF OPERATION

• US 20180074215A1
• Filed: 04/04/2016
• Published: 03/15/2018
• Est. Priority Date: 04/02/2015
• Status: Active Grant

• Current Assignee: Kromek Limited (Kromek Group PLC)
• Original Assignee: Kromek Limited (Kromek Group PLC)
• Inventors: MARSDEN, Edward
• Granted Patent: US 10,451,746 B2
• Time in Patent Office: Days
• CPC Class Codes: G01T 1/1647 Processing of scintigraphic data not related to a particular imaging system G01T1/2992
• CPC Class Codes: G01T 1/20184 Detector read-out circuitry, e.g. for clearing of traps, compensating for traps or compensating for direct hits
• CPC Class Codes: G01T 1/40 Stabilisation of spectrometers
• CPC Class Codes: G01T 7/005 calibration techniques stabilization of spectrometer G01T1/40

Abstract

A method of operation of a scintillator detector comprising a scintillator and a photodetector is described, together with a device embodying the method. The method comprises the steps of: periodically producing a light pulse; impinging at least some of the light from a successive plurality of such light pulses onto a light-receptive part of the photodetector; measuring the electrical response of the photodetector; processing the electrical response of the photodetector to determine a pulse height and a variance of pulse height; numerically processing the pulse height and variance of pulse height so determined to obtain at least a first data item characteristic of the response of the photodetector. The method additionally or alternatively comprises the steps of: periodically producing a light pulse including light in the ultraviolet spectrum; impinging at least some of the UV light from a successive plurality of such light pulses onto a light-receptive part of the scintillator; inducing photon emission in the scintillator in the visible spectrum; measuring the electrical response of the scintillator; processing the electrical response of the scintillator to obtain at least a data item characteristic of the response of the scintillator; and optionally verifying the electrical response of the scintillator by comparing at least the said data item against a predetermined reference response; and optionally additionally or alternatively outputting a control signal to the photodetector, which signal is modified in part responsive at least to the value of the said data item.

Claims

1. A method of operation of a scintillator detector comprising a scintillator and a photodetector, the method comprising:

periodically producing a light pulse;

impinging at least some of the light from a successive plurality of such light pulses onto a light-receptive part of the photodetector;

measuring the electrical response of the photodetector;

processing the electrical response of the photodetector to determine a pulse height and a variance of pulse height; and

numerically processing the pulse height and variance of pulse height so determined to obtain at least a first data item characteristic of the response of the photodetector.

2. The method in accordance with claim 1, comprising verifying the electrical response of the photodetector by comparing at least the first data item against a predetermined reference response.

3. The method in accordance with claim 1, comprising outputting a control signal to the photodetector, which signal is modified in part responsive at least to the value of the first data item.

4. The method in accordance with claim 1, comprising numerically processing the pulse height and variance of pulse height so determined to obtain at least a first data item characteristic of the response of the photodetector comprises generating a first data item correlated to the total number of photons detected at the photodetector.

5. The method in accordance with claim 1, wherein the light source is a light-emitting diode (LED) source comprising at least one LED.

6. The method in accordance with claim 1, wherein the scintillator comprises a gamma ray scintillator.

7. The method in accordance with claim 1, wherein the scintillator comprises a solid state scintillator.

8. The method in accordance with claim 1, wherein the scintillator comprises an alkali metal halide scintillator optionally doped with an activator.

9. The method in accordance with claim 1, wherein the photodetector comprises a photomultiplier.

10. The method in accordance with claim 1, wherein the photodetector comprises a silicon photomultiplier.

11. The method in accordance with claim 1, comprising a light source temperature compensation step, wherein a measurement is taken of the temperature of the light source, and a correction factor is applied to the measured response of the photodetector, for example dynamically pulse by pulse, that corrects for the known variation of the light output of the light source with temperature.

12. The method in accordance with claim 1, comprising a photodetector temperature compensation step, wherein a measurement is taken of the temperature of the photodetector, and a correction factor is applied to the measured response of the photodetector, for example dynamically pulse by pulse, that corrects for the known variation of the photodetector response with temperature.

13. The method in accordance with claim 1, wherein a light source is provided configured to emit light in the visible spectrum.

14. The method in accordance with claim 1, wherein a light source is provided configured to emit light in the ultraviolet spectrum.

15. The method in accordance with claim 14, comprising:

periodically producing a light pulse including light in the ultraviolet spectrum;

impinging at least some of the UV light from a successive plurality of such light pulses onto a light-receptive part of the scintillator;

measuring the electrical response of the scintillator;

processing the electrical response of the scintillator to obtain at least a second data item characteristic of the response of the scintillator;

and optionally verifying the electrical response of the scintillator by comparing at least the second data item against a predetermined reference response; and

optionally additionally or alternatively outputting a control signal to the photodetector, which signal is modified in part responsive at least to the value of the second data item.

16. The method in accordance with claim 15, comprising the use of a visible light source impinging on the photodetector to obtain the first data item and thereby a measure of photodetector gain change and the use of a separate ultraviolet light source impinging on the scintillator to obtain the second data item and thereby a measure of scintillator brightness.

17. The method in accordance with claim 16, employing a visible light LED source and a UV LED source.

18. The method in accordance with claim 17, wherein the visible LED source comprises a second UV LED source equivalent to first LED source but overcoated with a temperature stable fluorescent material to fluoresce in the visible spectrum.

20. A scintillator detector comprising a scintillator and a photodetector adapted to perform the method of claim 1.

19. A method of operation of a scintillator detector comprising a scintillator and a photodetector, the method comprising:

periodically producing a light pulse including light in the ultraviolet spectrum;

impinging at least some of the UV light from a successive plurality of such light pulses onto a light-receptive part of the scintillator;

inducing photon emission in the scintillator in the visible spectrum;

measuring the electrical response of the scintillator;

processing the electrical response of the scintillator to obtain at least a data item characteristic of the response of the scintillator;

optionally verifying the electrical response of the scintillator by comparing at least the scintillator response data item against a predetermined reference response; and

optionally additionally or alternatively outputting a control signal to the photodetector, which signal is modified in part responsive at least to the value of the scintillator response data item.

21. A scintillator detector comprising:

a scintillator;

a photodetector;

a pulsed light source positioned to illuminate a light-receptive part of the photodetector;

a means to measure the electrical response of the photodetector;

a processing module to process the electrical response of the photodetector and determine a pulse height and a variance of pulse height, and to numerically process the pulse height and variance of pulse height so determined to obtain at least a first data item characteristic of the response of the photodetector;

optionally a verifier to verify the electrical response of the photodetector by comparing at least the first data item against a predetermined reference response; and

optionally additionally or alternatively a control module to output a control signal to the photodetector, which signal is modified in part responsive at least to the value of the first data item.

22. The scintillator detector in accordance with claim 21, wherein the light source is a light-emitting diode (LED) source comprising at least one LED.

23. The scintillator detector in accordance with claim 21, wherein the scintillator comprises a gamma ray scintillator.

24. The scintillator detector in accordance with claim 21, wherein the scintillator comprises a neutron scintillator.

25. The scintillator detector in accordance with claim 21, wherein the scintillator comprises a solid state scintillator.

26. The scintillator detector in accordance with claim 21, wherein the scintillator comprises an alkali metal halide scintillator optionally doped with an activator.

27. The scintillator detector in accordance with claim 21, wherein the photodetector comprises a photomultiplier.

28. The scintillator detector in accordance with claim 27, wherein the photodetector comprises a silicon photomultiplier.

29. The scintillator detector in accordance with claim 21, wherein a light source is provided configured to emit light in the visible spectrum.

30. The scintillator detector in accordance with claim 21, wherein a light source is provided configured to emit light in the ultraviolet spectrum.

31. The scintillator detector in accordance with claim 30, wherein a source of pulsed UV light is provided positioned to illuminate a light-receptive part of the scintillator, the scintillator detector comprising:

means to measure the electrical response of the scintillator;

a processing module to process the electrical response of the scintillator and obtain at least a second data item characteristic of the response of the scintillator;

optionally a verifier to verify the electrical response of the scintillator by comparing the second data item against a predetermined reference response; and

optionally additionally or alternatively a control module to output a control signal to the photodetector, which signal is modified in part responsive at least to the value of the second data item.

33. The scintillator detector in accordance with claim 21, the component elements of which are provided compactly associated together in a housing for portable operation.

32. A scintillator detector comprising:

a scintillator;

a photodetector;

a source of pulsed UV light positioned to illuminate a light-receptive part of the scintillator;

means to measure the electrical response of the scintillator;

a processing module to process the electrical response of the scintillator and obtain a data item characteristic of the response of the scintillator;

optionally a verifier to verify the electrical response of the scintillator by comparing the scintillator response data item against a predetermined reference response; and

optionally additionally or alternatively a control module to output a control signal to the photodetector, which signal is modified in part responsive at least to the value of the scintillator response data item.