Dual energy imaging using optically coupled digital radiography system

• US 20060133571A1
• Filed: 12/01/2005
• Published: 06/22/2006
• Est. Priority Date: 08/08/2003
• Status: Active Grant

• Current Assignee: 1370509 Alberta Inc.
• Original Assignee: Imaging Dynamics Company Ltd.
• Inventors: Winsor, Robin
• Granted Patent: US 7,330,532 B2
• Time in Patent Office: Days
• US Class Current: 378/98.800
• CPC Class Codes: A61B 6/4035 the source being combined with a filter or grating
• CPC Class Codes: A61B 6/482 involving multiple energy imaging
• CPC Class Codes: A61B 6/505 for diagnosis of bone
• CPC Class Codes: G01T 1/362 with scintillation detectors see provisionally also G01T1/36, G01T1/20

Abstract

This invention relates to an optically coupled digital radiography method and apparatus for simultaneously obtaining two distinct images of the same subject, each of which represents a different x-ray energy spectrum. The two images may be combined in various ways such that anatomical features may be separated from one another to provide a clearer view of those features or of underlying structures. The two different images are obtained using a pair of scintillators separated by an x-ray filter that attenuates part of the x-ray spectrum of an x-ray exposure such that the first and second scintillators receive a different energy spectrum of the same x-ray exposure Alternatively, the two different images can be obtained without a filter and with two scintillators made of different fluorescing materials that react differently to the same x-ray exposure.

Claims

1. An optically-coupled digital radiography system for simultaneously producing multiple images of differing energies of a subject from a single x-ray exposure of the subject, the system comprising:

(a) a first scintillator that produces a visible first image when subjected to an x-ray exposure of a subject, the first scintillator being positioned at an oblique angle to the x-ray exposure;

(b) a first digital camera, optically coupled to the first scintillator, for capturing the first image directly without reflection from reflection means interposed between said first camera and said first scintillator, positioned out of the path of the x-ray exposure;

(c) an x-ray filter positioned in the path of the x-ray exposure and downstream of the first scintillator, for selectively attenuating a portion of the x-ray spectrum of the x-rays that have passed through the first scintillator;

(d) a second scintillator positioned in the path of and at an oblique angle to the x-ray exposure and downstream of the filter and that produces a visible second image when subjected to x-rays that have passed through the filter, the second image being different than the first image; and

(e) a second digital camera, optically coupled to the second scintillator, for capturing the second image directly and without reflection from reflection means interposed between said second camera and said second scintillator, positioned out of the path of the x-ray exposure.

2. The system of claim 1 wherein the filter, first and second scintillators are positioned substantially parallel to each other.

3. The system of claim 2 wherein the filter has sufficient mechanical strength to support the first and second scintillators, and the first and second scintillators are each mounted to respective sides of the filter.

4. The system of claim 1 wherein the first and second scintillators have a fluorescing material selected from the group of CaWO₄, BaPbSO₄, BaFCl:

Eu, LaOBr;

Tm, Y₂O₂S;

Tb, CsI;

Tl, Gd₂O₂S;

Tb, and BaSrSO₄;

Eu.

5. The system of claim 4 wherein the first and second scintillators each have different fluorescing materials that respond differently to the x-ray exposure.

6. The system of claim 1 wherein the second scintillator is a Lambertian emitter.

7. The system of claim 1 further comprising a radiation blocking layer positioned between the first digital camera and an x-ray source emitting the x-ray exposure.

8. The system of claim 1 further comprising a radiation blocking layer positioned between the second digital camera and an x-ray source emitting the x-ray exposure.

9. The system as claimed in claim 1 wherein the first digital camera is positioned so as to capture the first image without the first image ever having been combined with the second image.

10. An optically-coupled digital radiography system for simultaneously producing multiple images of differing energies of a subject from a single x-ray exposure of the subject, the system comprising:

(a) a first scintillator that produces a visible first image when subjected to an x-ray exposure of a subject;

(b) an x-ray filter coated on each side with first and second reflective layers and positioned in the path of the x-ray exposure and downstream of the first scintillator, for selectively attenuating a portion of the x-ray spectrum of the x-rays that have passed through the first scintillator;

(c) a second scintillator positioned in the path of the x-ray exposure and downstream of the filter and that produces a visible second image when subjected to x-rays that have passed through the filter, the second image being different than the first image;

(d) a first digital camera for capturing the first image, located out of the path of the x-ray exposure and optically coupled to the first scintillator by the first reflective layer; and

(e) a second digital camera for capturing the second image, located out of the path of the x-ray exposure and optically coupled to the second scintillator by the second reflective layer

11. The system of claim 10 wherein the second scintillator is positioned substantially parallel to the first scintillator.

12. The system of claim 11 wherein the filter is positioned at an oblique angle to the x-ray exposure such that the images produced by the first and second scintillators are reflected to the first and second cameras, respectively.

13. The system of claim 10 wherein the second scintillator is a Lambertian emitter.

14. The system of claim 10 further comprising a radiation blocking layer positioned between the first digital camera and an x-ray source emitting the x-ray exposure.

15. The system of claim 10 further comprising a radiation blocking layer positioned between the second digital camera and an x-ray source emitting the x-ray exposure.

16. The system as claimed in claim 10 wherein the first digital camera is positioned so as to capture the first image without the first image ever having been combined with the second image.

17. An optically-coupled digital radiography system for simultaneously producing multiple images of differing energies of a subject from a single x-ray exposure of the subject, the system comprising:

(a) a first scintillator comprising a first fluorescing material that produces a visible first image when subjected to an x-ray exposure of a subject, the first scintillator being positioned at an oblique angle to the x-ray exposure;

(b) a first digital camera, optically coupled to the first scintillator for capturing the first image directly and without reflection from reflection means interposed between said first camera and said first scintillator, positioned out of the path of the x-ray exposure;

(c) a second scintillator positioned in the path of and at an oblique angle to the x-ray exposure and downstream of the first scintillator and comprising a second fluorescing material that responds sufficiently differently to the x-ray exposure than the first scintillator material to produce a visible second image that is different from the first image; and

(d) a second digital camera, optically coupled to the second scintillator for capturing the second image directly and without reflection from reflection means interposed between said second camera and said second scintillator, positioned out of the path of the x-ray exposure.

18. The system of claim 17 further comprising an x-ray filter positioned in the path of the x-ray exposure and between the first and second scintillators, for selectively attenuating a portion of the x-ray spectrum of the x-rays that have passed through the first scintillator.

19. The system of claim 18 wherein the filter, first and second scintillators are positioned substantially parallel to each other

20. The system of claim 19 wherein the filter has sufficient mechanical strength to support the first and second scintillators, and the first and second scintillators are each mounted to respective sides of the filter.

21. The system of claim 17 wherein the fluorescing materials for the first and second scintillators are selected from the group CaWO₄, BaPbSO₄, BaFCl:

Eu, LaOBr;

Tm, Y₂O₂S;

Tb, CsI;

Tl, Gd₂O₂S;

Tb, and BaSrSO₄;

Eu.

22. The system of claim 17 wherein the second scintillator is a Lambertian emitter.

23. The system of claim 17 further comprising a radiation blocking layer positioned between the first digital camera and an x-ray source emitting the x-ray exposure.

24. The system of claim 17 further comprising a radiation blocking layer positioned between the second digital camera and an x-ray source emitting the x-ray exposure.

25. The system as claimed in claim 17 wherein the first digital camera is positioned so as to capture the first image without the first image ever having been combined with the second image.