Systems and methods for improving energy resolution by sub-pixel energy calibration

Patent metadata

Field	Value
Publication number	US-9696440-B2
Application number	US-201514627436-A
Country	US
Kind code	B2
Filing date	Feb 20, 2015
Priority date	Feb 20, 2015
Publication date	Jul 4, 2017
Grant date	Jul 4, 2017

Abstract

A radiation detector assembly is provided including a semiconductor detector, pixelated anodes, and at least one processor. The pixelated anodes are disposed on a surface of the semiconductor detector, and configured to generate a primary signal responsive to reception of a photon and a secondary signal responsive to an induced charge caused by reception of a photon by at least one adjacent anode. The at least one processor is operably coupled to the pixelated anodes, and configured to define sub-pixels for each pixelated anode; acquire primary signals and secondary signals from the pixelated anodes; determine sub-pixel locations for acquisition events using the primary and secondary signals; generate a sub-pixel energy spectrum for each sub-pixel; apply at least one energy calibration parameter to adjust the sub-pixel energy spectra for each pixelated anode; and, for each pixelated anode, combine the adjusted sub-pixel energy spectra to provide a pixelated anode spectrum.

First claim

What is claimed is:

1. A radiation detector assembly comprising:
a semiconductor detector having a surface;
plural pixelated anodes disposed on the surface, each pixelated anode configured to generate a primary signal responsive to reception of a photon by the pixelated anode and to generate at least one secondary signal responsive to an induced charge caused by reception of a photon by at least one adjacent anode; and
at least one processor operably coupled to the pixelated anodes, the at least one processor configured to:
define sub-pixels for each pixelated anode;
acquire primary signals and secondary signals corresponding to acquisition events from the pixelated anodes;
determine sub-pixel locations for the acquisition events using the primary signals and the secondary signals;
generate a sub-pixel energy spectrum for each sub-pixel, using the primary signals, to produce sub-pixel energy spectra;
apply at least one energy calibration parameter to adjust the sub-pixel energy spectra for each pixelated anode to produce calibrated sub-pixel energy spectra; and
for each pixelated anode, combine the calibrated sub-pixel energy spectra to provide a pixelated anode spectrum.

2. The detector assembly of claim 1 , wherein the at least one processor is configured to align respective peaks of the sub-pixel energy spectra for each pixelated anode using the at least one energy calibration parameter.

3. The detector assembly of claim 1 , wherein the at least one energy calibration parameter is selected from a group of parameters comprising a gain and an offset, wherein applying the gain adjusts a position and a breadth of a peak of an energy spectrum being adjusted and applying the offset shifts a peak location of the spectrum being adjusted.

4. The detector assembly of claim 1 , wherein at least a portion of the at least one processor is integrated with the semiconductor detector.

5. The detector assembly of claim 4 , wherein the at least a portion of the at least one processor comprises at least one of an application specific integrated circuit (ASIC) or field programmable gate array (FPGA).

6. The detector assembly of claim 1 , wherein the at least one processor is housed externally from the semiconductor detector.

7. The detector assembly of claim 1 , wherein the at least one processor is configured to bin primary signals for each sub-pixel based on energy level to provide a histogram of counts of primary signals counted against energy level to generate the sub-pixel energy spectrum for each sub-pixel.

8. The detector assembly of claim 1 , wherein the at least one processor is configured to assign a corresponding electrical channel to each pixelated anode, wherein each channel has associated therewith a threshold discriminator having a threshold level configured to allow collection of events corresponding to an induced electrical charge in an adjacent anode caused by reception of a photon by the adjacent anode.

9. A method of imaging using a semiconductor detector having a surface with plural pixelated anodes disposed thereon, each pixelated anode configured to generate a primary signal responsive to reception of a photon by the pixelated anode and to generate at least one secondary signal responsive to an induced charge caused by reception of a photon by at least one adjacent anode, the method comprising:
defining, with at least one processor operably coupled to the pixelated anodes, sub-pixels for each pixelated anode;
acquiring, with the at least one processor, primary signals and secondary signals corresponding to acquisition events from the pixelated anodes;
determining, with the at least one processor, sub-pixel locations for the acquisition events using the primary signals and the secondary signals;
generating, with the at least one processor, a sub-pixel energy spectrum for each sub-pixel using the primary signals, to produce sub-pixel energy spectra;
applying, with the at least one processor, at least one energy calibration parameter to adjust the sub-pixel energy spectra for each pixelated anode to produce calibrated sub-pixel energy spectra ; and
for each pixelated anode, combining the calibrated sub-pixel energy spectra to provide a pixelated anode spectrum.

10. The method of claim 9 , further comprising reconstructing the image using the pixelated anode spectrum from each pixelated anode.

11. The method of claim 9 , further comprising aligning, with the at least one processor, respective peaks of the sub-pixel energy spectra for each pixelated anode using the at least one energy calibration parameter.

12. The method of claim 9 , wherein the at least one energy calibration parameter is selected from a group of parameters comprising a gain and an offset, wherein applying the gain adjusts a position and a breadth of a peak of an energy spectrum being adjusted and applying the offset shifts the peak location of the spectrum.

13. The method of claim 9 , further comprising binning primary signals for each sub-pixel based on energy level to provide a histogram of counts of primary signals plotted against energy level to generate the sub-pixel energy spectrum for each sub-pixel.

14. A method of providing a radiation detector assembly comprising:
providing a semiconductor detector having a surface with plural pixelated anodes disposed thereon, each pixelated anode configured to generate a primary signal responsive to reception of a photon by the pixelated anode and to generate at least one secondary signal responsive to an induced charge caused by reception of a photon by at least one adjacent anode;
operably coupling the pixelated anodes to at least one processor;
defining, with the at least one processor, sub-pixels for each pixelated anode;
providing a calibrated radiation supply to the semiconductor detector, wherein the pixelated anodes generate primary signals and secondary signals responsive to the calibrated radiation supply;
acquiring, with the at least one processor, the primary signals and the secondary signals from the pixelated anodes;
determining sub-pixel locations for calibrated acquisition events using the primary and the secondary signals generated responsive to the calibrated radiation supply;
generating a non-calibrated sub-pixel energy spectrum for each sub-pixel, using the primary signals, to produce non-calibrated sub-pixel energy spectra;
determining at least one calibration parameter to align the non-calibrated energy spectra with an expected spectrum; and
applying the at least one determined calibration parameter to the non-calibrated sub-pixel energy spectra to generate calibrated sub-pixel energy spectra.

15. The method of claim 14 , further comprising, for each pixelated anode, combining the calibrated sub-pixel energy spectra to provide a pixelated anode spectrum.

16. The method of claim 14 , wherein determining the at least one calibration parameter comprises determining an offset, wherein applying the offset shifts the peak location of a spectrum being adjusted.

17. The method of claim 16 , where determining the at least one calibration parameter further comprises determining a gain, wherein applying the gain adjusts an amplitude of the spectrum being adjusted.

18. The method of claim 14 , wherein the calibrated radiation supply includes radiation from a first isotope and a second isotope, the second isotope having a different radiation energy than the first isotope.

19. The method of claim 14 , wherein the calibration parameters are configured to align respective peaks of the non-cali

Assignees

• Gen Electric

Inventors

• Shahar Arie
• Fries Mark David
• Glazer Yaron
• Levy Jeffrey Michael
• Ofan Avishai
• Har-Lavan Rotem

Classifications

• G01T1/249

  specially adapted for use in SPECT or PET (SPECT imaging G01T1/1642; PET imaging G01T1/2985; detecting prohibited goods, e.g. weapons, explosives, hazardous substances, contraband or smuggled objects G01V5/20) · CPC title

• G01T7/005 Primary

  calibration techniques (stabilization of spectrometer G01T1/40) · CPC title

• G01J1/4228

  arrangements with two or more detectors, e.g. for sensitivity compensation · CPC title

• G01J2001/442

  Single-photon detection or photon counting · CPC title