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1. US20130259194 - HYBRID SLOT-SCANNING GRATING-BASED DIFFERENTIAL PHASE CONTRAST IMAGING SYSTEM FOR MEDICAL RADIOGRAPHIC IMAGING

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Claims

1. A slot-scanning phase-contrast digital radiographic imaging system comprising:
a polychromatic x-ray source for radiographic imaging;
a beam shaping assembly comprising,
a collimator,
a source grating G 0,
an x-ray grating interferometer comprising
a phase grating G 1, and
an analyzer grating G 2; and
an area x-ray detector; wherein the three gratings (G 0, G 1, and G 2) are positioned in such a way that the plane and the grating bars of these gratings are aligned to each other.
2. The slot-scanning phase-contrast digital mammography system of claim 1, wherein an orientation of the grating bars of the three gratings (G 0, G 1, and G 2) is perpendicular to the scan direction of the swing arm.
3. The slot-scanning phase-contrast digital mammography system of claim 1, wherein an orientation of the grating bars of the three gratings (G 0, G 1, and G 2) is parallel to the scan direction of the swing arm.
4. The slot-scanning phase-contrast digital mammography system of claim 1, where an aspect ratio of the second grating and the third grating are each greater than 2:1.
5. The slot-scanning phase-contrast digital mammography system of claim 1, wherein the x-ray source, the beam shaping assembly, the grating interferometer, and the detector are attached to a swing arm to pivot together around an axis.
6. The slot-scanning phase-contrast digital mammography system of claim 5, where the axis is positioned on a side of the source grating G 0 opposite the analyzer grating G 2 including co-axial with a x-ray tube focal spot.
7. The slot-scanning phase-contrast digital mammography system of claim 1, where for each of a plurality of N positions of the analyzer grating G 2, the swing arm performs a single FOV scan by exposing M sequential positions of the area x-ray detector to obtain a plurality of raw image data used to construct a 3D image, where M and N are positive integers greater than 4.
8. The slot-scanning phase-contrast digital mammography system of claim 7, where the M sequential positions of the area x-ray detector are a plurality of adjacent overlapping positions, where gratings of the analyzer grating G 2 are substantially parallel or substantially perpendicular to an x-ray beam path.
9. The slot-scanning phase-contrast digital mammography system of claim 1, where for each of a plurality of N positions of the analyzer grating G 2, the swing arm performs a M FOV scans by continuously slot-scanning M portions of the FOV using a CCD detector in TDI mode to obtain a plurality of raw image data used to construct a 3D image, where M and N are positive integers.
10. The slot-scanning phase-contrast digital mammography system of claim 9, where the M portions of the FOV are sequentially adjacent positions of the FOV, where gratings of the analyzer grating G 2 are substantially parallel to an x-ray beam path.
11. The slot-scanning phase-contrast digital mammography system of claim 1, where the swing arm performs a single FOV scan by exposing M sequential positions of the area x-ray detector, where each of the M sequential positions are exposed for each of a plurality of N positions of the analyzer grating G 2 to obtain a plurality of raw image data used to construct a 3D image, where M and N are positive integers.
12. The slot-scanning phase-contrast digital mammography system of claim 11, where the M sequential positions of the area x-ray detector are a plurality of adjacent overlapping positions, where gratings of the analyzer grating G 2 are substantially parallel or substantially perpendicular to an x-ray beam path.
13. The slot-scanning phase-contrast digital mammography system of claim 1, wherein the same image data set is used to construct multiple images of the object including absorption contrast images, differential phase contrast images, phase shift contrast images, and dark-field images.
14. The slot-scanning phase-contrast digital mammography system of claim 1, further comprising a filter, where the detector is an indirect area detector or a direct area detector, where the gratings and detector are curved to match the source x-ray focus, where the phase grating G 1 and the analyzer grating G 2 have a prescribed angle therebetween, where the analyzer grating G 2 can be stepped linearly or stepped rotationally.
15. A phase-contrast digital radiographic imaging system comprising:
a polychromatic x-ray source for radiographic imaging;
a beam shaping assembly comprising a source grating G 0,
an x-ray grating interferometer comprising
a phase grating G 1, and
an analyzer grating G 2; and
where a pitch and a position of the analyzer grating G 2 relative to a pitch of an interference pattern produced by the phase grating G 1 produce at least one fringe pattern over a width of the analyzer grating G 2.
16. The system of claim 15, where the fringe pattern is produced by the pitch of the analyzer grating G 2 being unequal to the pitch of an interference pattern produced by the phase grating G 1 at a position of the analyzer grating G 2.
17. The system of claim 16, where the analyzer grating G 2 is at a Talbot distance or a position to increase contrast at the position of the detector, where the relative position of the phase grating G 1 and the analyzer grating G 2 does not change for a scan of an object.
18. The system of claim 15, where the fringe pattern is produced by the position of the analyzer grating G 2 is offset from a Talbot distance, and where the pitch of the analyzer grating G 2 is equal to a pitch of the interference pattern.
19. The system of claim 15, where the phase-contrast digital radiographic imaging system is detuned, and where the relative position of the phase gratings G 1 and the analyzer grating G 2 does not change for a complete scan of an object.
20. The system of claim 15, where the phase-contrast digital radiographic imaging system is detuned to produce a fringe pattern that is greater than 0.1 cm, or over a significant portion of the analyzer grating G 2.
21. The system of claim 15, where N is a number of steps used to cover a period of the analyzer grating G 2, and where a scan of the object includes N exposures of at least one portion of the object.
22. The system of claim 15, where the grating G 1, the grating G 2 and the detector D can be fixed at one relative position, attached to the swing arm and moved to image the object, where the relative position of the grating G 1 and the grating G 2 provide a non-zero Δf=f int−f 2.
23. The system of claim 15, where a frequency (Δf) of fringe pattern at the detector can be adjusted.
24. The system of claim 23, where the analyzer grating G 2 can be moved offset relative to the phase grating G 1 to adjust the frequency (Δf) of fringe pattern at the detector, or the analyzer grating G 2 and the detector D can be moved simultaneously together in the direction of the x-ray beam to increase a contrast or adjust the fringe pattern at the detector.
25. The system of claim 15, where the phase-contrast DR imaging system is a slot-scanning phase-contrast DR imaging system, where an orientation of the grating bars of the three gratings G 0, G 1, and G 2 is parallel to the scan direction of the swing arm, where an image data set from a single pass of the system over an object is used to construct multiple images of the object including at least one of absorption contrast images, differential phase contrast images, phase shift contrast images, and dark-field images.
26. A phase-contrast digital radiographic imaging system comprising:
a polychromatic x-ray source for radiographic imaging;
a beam shaping assembly comprising a source grating G 0,
an x-ray grating interferometer comprising
a phase grating G 1, and
an analyzer grating G 2; and
an area x-ray detector,
where a pitch of the analyzer grating G 2 relative to a pitch of an interference pattern produced by the phase grating G 1 are unequal at a position of the area x-ray detector.
27. The system of claim 26, where the phase-contrast digital radiographic imaging system is detuned to produce a fringe pattern over a significant portion of the analyzer grating G 2, where the relative position of the phase gratings G 1 and the analyzer grating G 2 does not change for a scan of an object, where N is a number of steps used to cover a period of the analyzer grating G 2, and where the scan of the object includes N exposures of at least one portion of the object.