Measurement masks to reconstruct X-ray spectra

Patent metadata

Field	Value
Publication number	US-11079343-B2
Application number	US-202117158676-A
Country	US
Kind code	B2
Filing date	Jan 26, 2021
Priority date	Mar 26, 2019
Publication date	Aug 3, 2021
Grant date	Aug 3, 2021

Abstract

An X-ray imaging system for reconstructing X-ray spectra includes an integrating detector and a measurement mask, including at least one physical filter, positioned between the integrating detector and an X-ray source spectrum. The integrating detector receives a masked X-ray spectrum after the source spectrum has been filtered in accordance with the measurement mask. As a result of the measurement mask containing one or more physical filters being combined, a measurement mask having energy band-pass regions can be generated, to cover the source spectrum. Measured data, based on the masked X-ray spectrum and characteristics of the measurement mask, is collected from the integrating detector. The X-ray imaging system reconstructs an X-ray spectrum and generates the reconstructed X-ray spectrum based on applying a predetermined algorithm, such as total variation minimization reconstruction, to the measured data.

First claim

The invention claimed is:

1. A system for reconstructing X-ray spectra, comprising:
a measurement mask including at least one physical filter positioned between an X-ray source that emits X-ray energy according to a source spectrum and an integrating detector to filter the source spectrum to produce a masked spectrum; and
processing circuitry configured to generate a reconstructed spectrum, serving as a representation of the source spectrum that has been mathematically reconstructed, based on applying a predetermined algorithm to measured data collected from the integrating detector and using an identified configuration of the measurement mask.

2. The system of claim 1 , wherein the measurement mask includes a plurality of physical filters of a corresponding plurality of energy band-pass regions to filter at least a portion of the source spectrum.

3. The system of claim 2 , wherein the plurality of physical filters is arranged in a pseudo-random pattern to achieve an aggregate wide energy band-pass region of the measurement mask to cover energies of the source spectrum.

4. The system of claim 2 , wherein the plurality of physical filters is arranged corresponding to ordered mathematical combinations to achieve an aggregate wide energy band-pass region of the measurement mask to cover energies of the source spectrum.

5. The system of claim 1 , wherein the measurement mask includes a plurality of physical filters configured and arranged to filter the source spectrum according to a sub-pixel basis, wherein a given sub-pixel of the measurement mask is smaller in area than a given pixel of the integrating detector.

6. The system of claim 5 , wherein the plurality of physical filters of the measurement mask are arranged to provide four sub-pixels of filtering for each pixel of the integrating detector.

7. The system of claim 1 , wherein the measurement mask provides the at least one physical filter comprising a plurality of metal foils, associated with corresponding pluralities of enhanced X-ray energy absorption edges and attenuation values, arranged in a two-dimensional grid corresponding to pixels of the integrating detector.

8. The system of claim 7 , wherein the two-dimensional grid includes at least one overlapping plurality of metal foils corresponding to providing an attenuation value of the at least one overlapping plurality of metal foils for at least a given sub-pixel of the integrating detector.

9. The system of claim 8 , wherein the at least one overlapping plurality of metal foils corresponds to at least a given pixel of the integrating detector.

10. The system of claim 1 , wherein the predetermined algorithm is configured to perform a total variation minimization reconstruction.

11. The system of claim 10 , wherein the reconstructed spectrum is generated based on an iterative application of the total variation minimization reconstruction to iteratively check whether convergence of the reconstructed spectrum has been reached.

12. The system of claim 1 , wherein the measurement mask is positioned between the X-ray source that emits X-ray energy according to the source spectrum and the integrating detector to enable the integrating detector to directly receive the masked spectrum during operation of the system.

13. The system of claim 12 , wherein the measurement mask is coupled to the integrating detector.

14. The system of claim 1 , wherein the measurement mask is positioned between the X-ray source that emits X-ray energy according to the source spectrum and the integrating detector to enable the measurement mask to directly receive the source spectrum during operation of the system.

15. The system of claim 14 , wherein the system further comprises a scintillator, and the measurement mask is coupled to the scintillator.

16. The system of claim 1 , wherein the system is configured to read a coded mask identification corresponding to a specific X-ray source anode material of the source spectrum, and determine an identified configuration of the at least one physical filter corresponding to the coded mask identification, the identified configuration to be used as the measurement mask.

17. A method comprising:
identifying a type of an X-ray source used in an imaging system to produce a source spectrum;
identifying a plurality of physical filters to provide a plurality of respective corresponding wide energy band-pass regions suitable to filter the source spectrum;
identifying a configuration of the plurality of physical filters that when combined into a measurement mask achieve an aggregate wide energy band-pass region to cover energies of the source spectrum;
filtering, by the imaging system, X-ray energy emitted by the X-ray source in accordance with the measurement mask, including the configuration of the plurality of physical filters, positioned between the X-ray source and an integrating detector of the imaging system, to filter the source spectrum to produce a masked spectrum; and
generating a reconstructed spectrum based on applying a predetermined algorithm to measured data that is collected from the integrating detector, the predetermined algorithm accounting for the configuration of the plurality of physical filters.

18. The method of claim 17 , further comprising diagnosing a degradation of the X-ray source, based on identifying changes in the reconstructed spectrum, relative to a baseline characteristic of the X-ray source, over time with repeated usage of the X-ray source.

19. The method of claim 18 , further comprising providing feedback, based on the diagnosed degradation, that the X-ray source needs to be serviced.

20. The method of claim 17 , further comprising identifying changes in the reconstructed spectrum in real-time, to detect changes in stability of imaged rapidly evolving explosives.

Assignees

• The Government Of The Us Secretary Of Homeland Security

Inventors

• Klueg Robert E

Classifications

• G01T1/36

  Measuring spectral distribution of X-rays or of nuclear radiation {spectrometry (pulse selection circuits per se H03K; investigation of materials by radiation diffraction G01N23/20; spectrometer tubes H01J49/00)} · CPC title

• G01N23/087 Primary

  using polyenergetic X-rays · CPC title

• G01T1/362

  with scintillation detectors · CPC title