X-RAY PHASE-CONTRAST IMAGING

• US 20160135769A1
• Filed: 11/17/2015
• Published: 05/19/2016
• Est. Priority Date: 11/17/2014
• Status: Active Grant

• Current Assignee: Rensselaer Polytechnic Institute
• Original Assignee: Rensselaer Polytechnic Institute
• Inventors: Wang, Ge, Xi, Yan, Cong, Wenxiang
• Granted Patent: US 9,801,600 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61B 6/032 Transmission computed tomography [CT]
• CPC Class Codes: A61B 6/4035 the source being combined with a filter or grating
• CPC Class Codes: A61B 6/4233 using matrix detectors
• CPC Class Codes: A61B 6/4291 the detector being combined with a grid or grating
• CPC Class Codes: A61B 6/484 involving phase contrast X-ray imaging
• CPC Class Codes: A61B 6/5205 involving processing of raw data to produce diagnostic data
• CPC Class Codes: G06T 11/005 Specific pre-processing for tomographic reconstruction, e.g. calibration, source positioning, rebinning, scatter correction, retrospective gating
• CPC Class Codes: G06T 2211/461 Phase contrast imaging or dark field imaging
• CPC Class Codes: G21K 1/025 using multiple collimators, e.g. Bucky screens; other devices for eliminating undesired or dispersed radiation
• CPC Class Codes: G21K 2207/005 Methods and devices obtaining contrast from non-absorbing interaction of the radiation with matter, e.g. phase contrast

Abstract

Systems and methods for X-ray phase-contrast imaging (PCI) are provided. A quasi-periodic phase grating can be positioned between an object being imaged and a detector. An analyzer grating can be disposed between the phase grating and the detector. Second-order approximation models for X-ray phase retrieval using paraxial Fresnel-Kirchhoff diffraction theory are also provided. An iterative method can be used to reconstruct a phase-contrast image or a dark-field image.

Claims

1. An X-ray phase-contrast imaging (PCI) system, comprising:

an X-ray source;

a detector;

a first grating disposed between the energy source and the detector; and

a second grating disposed between the first grating and the detector,

wherein the first grating is a quasi-periodical phase grating such that the period of the grating varies across the grating.

2. The system according to claim 1, wherein the second grating is an analyzer grating.

5. The system according to claim 1, wherein the second grating is flat.

6. The system according to claim 1, wherein the first grating is curved.

7. The system according to claim 6, wherein the first grating is a cylindrical grating or a spherical grating.

8. The system according to claim 1, wherein the detector is flat,

wherein the second grating is flat, and

wherein the first grating is a cylindrical grating or a spherical grating.

9. The system according to claim 1, further comprising a source grating disposed between the energy source and the first grating.

10. The system according to claim 9, wherein the source grating is a cylindrical grating or a spherical grating.

11. The system according to claim 1, wherein the period of the first grating varies the same way in both lateral directions as the angle is varied positively or negatively by the same amount from a point on the first grating where X-rays from the X-ray source are centered during imaging.

12. A method of performing X-ray phase-contrast imaging, comprising:

providing the imaging system according to claim 1;

positioning an object to be imaged between the energy source and the first grating; and

imaging the object using the system.

13. The method according to claim 12, wherein the detector is flat,

wherein the second grating is flat, and

wherein the first grating is a cylindrical grating or a spherical grating

14. The method according to claim 13, wherein the second grating is an analyzer grating.

15. The method according to claim 13, wherein the imaging system further comprises a source grating disposed between the energy source and the first grating,

wherein the source grating is a cylindrical grating or a spherical grating,

and wherein the object is positioned between the source grating and the first grating for imaging of the object.

3. The system according to claiml, wherein the detector is flat.

4. The system according to claim 3, wherein the detector is a flat detector array.

16. A method of reconstructing or retrieving an X-ray phase image, the method comprising:

approximating the image with a second-order approximation model using paraxial Fresnel-Kirchhoff diffraction theory using the following equation;

17. The method according to claim 16, further comprising performing an iterative method to reconstruct at least one of a phase-contrast image and a dark-field image.

18. The method according to claim 17, wherein the iterative method includes iteratively solving the following equation:

19. The method according to claim 18, further comprising iteratively solving the model using the algebraic reconstruction technique (ART).

20. A non-transitory machine-readable medium having machine-executable instructions stored thereon for performing the method according to claim 19.