Dark field computed tomography imaging

Patent metadata

Field	Value
Publication number	US-9761021-B2
Application number	US-201314397878-A
Country	US
Kind code	B2
Filing date	May 13, 2013
Priority date	May 14, 2012
Publication date	Sep 12, 2017
Grant date	Sep 12, 2017

Abstract

A method includes obtaining a dark-field signal generated from a dark-field CT scan of an object, wherein the dark-field CT scan is at least a 360 degree scan. The method further includes weighting the dark-field signal. The method further includes performing a cone beam reconstruction of the weighted dark-field signal over the 360 degree scan, thereby generating volumetric image data. For an axial cone-beam CT scan, in one non-limiting instance, the cone-beam reconstruction is a full scan FDK cone beam reconstruction. For a helical cone-beam CT scan, in one non-limiting instance, the dark-field signal is rebinned to wedge geometry and the cone-beam reconstruction is a full scan aperture weighted wedge reconstruction. For a helical cone-beam CT scan, in another non-limiting instance, the dark-field signal is rebinned to wedge geometry and the cone-beam reconstruction is a full scan angular weighted wedge reconstruction.

First claim

The invention claimed is:

1. A method, comprising:
obtaining a dark-field signal generated from a dark-field CT scan of an object, wherein the dark-field CT scan is at least a 360 degree scan;
weighting the dark-field signal; and
performing a cone beam reconstruction of the weighted dark-field signal over the 360 degree scan, thereby generating volumetric image data.

2. The method of claim 1 , wherein the cone beam reconstruction does not require a complementary dark-field signal for the scanned object, which is a signal acquired one hundred and eighty degrees apart from the dark-field signal.

3. The method of claim 1 , wherein the cone beam reconstruction is an extension of a 2D filtered back-projection reconstruction over the 360 degree scan.

4. The method of claim 3 , wherein the 2D filtered back-projection reconstruction includes a term that is a function of the complementary dark-field signal, and further comprising:
approximating the complementary dark-field signal in the term with the dark-field signal.

5. The method of claim 3 , wherein the 2D filtered back-projection reconstruction includes applying a filtered back-projection to the weighted dark-field signal and multiplying a result of the filtered back-projection by a value of two.

6. The method of claim 1 , wherein the dark-field CT scan is an axial cone-beam CT scan, and the cone-beam reconstruction is a 360 degree FDK cone beam reconstruction.

7. The method of claim 1 , wherein the dark-field CT scan is a helical cone-beam CT scan.

8. The method of claim 7 , further comprising:
rebinning the dark-field signal to a wedge geometry, and wherein the cone-beam reconstruction is an aperture weighted wedge reconstruction.

9. The method of claim 7 , further comprising:
rebinning the dark-field signal to a wedge geometry, and wherein the cone-beam reconstruction is an angular weighted wedge reconstruction.

10. The method of any claim 9 , wherein the weights of all views with distance 2πadd to ½ independently.

11. An imaging system, comprising:
a source that emits radiation at a focal spot that traverses an examination region;
an interferometer that filters the emitted radiation for a dark-field imaging scan of an object; and
a detector array that detects the filtered radiation traversing the examination region and produces a dark-field signal indicative thereof; and
a reconstructor that weights the dark-field signal and reconstructs the weighted dark-field signal over 360 degrees using a cone beam reconstruction, generating volumetric image data,
wherein the cone beam reconstruction does not require a complementary dark-field signal for the scanned object, which is a signal acquired one hundred and eighty degrees apart from the dark-field signal.

12. The imaging system of claim 11 , wherein the reconstructor applies a cone beam reconstruction that is an extension of a 2D filtered back-projection reconstruction over the 360 degrees.

13. The imaging system of claim 12 , wherein the 2D filtered back-projection reconstruction includes a term that is a function of the complementary dark-field signal, which approximated with the dark-field signal.

14. The imaging system of claim 12 , wherein the 2D filtered back-projection reconstruction includes applying a filtered back-projection to the dark-field signal and multiplying a result of the filtered back-projection by a value of two.

15. The imaging system of claim 11 , wherein the dark-field CT scan is an axial cone-beam CT scan, and the reconstructor applies a 360 degree FDK cone beam reconstruction.

16. The imaging system of claim 11 , wherein the dark-field CT scan is a helical cone-beam CT scan.

17. The imaging system of claim 16 , wherein the reconstructor rebins the dark-field signal to a wedge geometry and applies an aperture weighted wedge reconstruction.

18. The imaging system of claim 16 , wherein the reconstructor rebins the dark-field signal to a wedge geometry and applies an angular weighted wedge reconstruction.

19. A computer readable storage medium encoded with computer readable instructions, which, when executed by a processor, cause the processor to:
obtain a dark-field signal generated from at least a 360 degree dark-field CT scan of an object;
weight the dark-field signal; and
perform a cone beam reconstruction on the weighted dark-field signal over 360 degrees, thereby generating volumetric image data.

20. The computer readable storage medium of claim 19 , wherein the dark-field CT scan is an axial cone-beam CT scan, and the cone-beam reconstruction is a full scan FDK cone beam reconstruction.

21. The computer readable storage medium of claim 20 , wherein the dark-field CT scan is a helical cone-beam CT scan, and the computer readable instructions, which, when executed by the processer, further cause the processor to:
rebin the dark-field signal to a wedge geometry; and
apply at least one of a 360 degree aperture or angular weighted wedge reconstruction to the rebinned dark-field signal.

22. The computer readable storage medium of claim 19 , wherein the cone-beam reconstruction is based on a fan-beam reconstruction.

23. The computer readable storage medium of claim 19 , wherein the cone-beam reconstruction is based on a parallel-beam reconstruction.

Assignees

• Koninklijke Philips Nv

Inventors

• Koehler Thomas
• Brendel Bernhard Johannes
• Roessl Ewald
• Van Stevendaal Udo

Classifications

• G01N23/046

  using tomography, e.g. computed tomography [CT] · CPC title

• A61B6/48

  Diagnostic techniques (A61B6/022, A61B6/025 A61B6/032, A61B6/037 take precedence) · CPC title

• A61B6/42

  Arrangements for detecting radiation specially adapted for radiation diagnosis · CPC title

• G01N2223/054

  small angle scatter · CPC title

• G06T2207/10081

  Computed x-ray tomography [CT] · CPC title