Method for coded-source phase contrast X-ray imaging

• US 10,045,752 B2
• Filed: 03/14/2013
• Issued: 08/14/2018
• Est. Priority Date: 05/14/2012
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology, The General Hospital Corporation (Mass General Brigham, Inc.)
• Original Assignee: Massachusetts Institute of Technology, The General Hospital Corporation (Mass General Brigham, Inc.)
• Inventors: Gupta, Rajiv, Velasquez-Garcia, Luis Fernando, Lanza, Richard, Horn, Berthold K P, Akinwande, Akintunde Ibitayo
• Primary Examiner(s): Ho, Allen C.
• Application Number:
  US14/400,703
• Publication Number:
  US 20150146848A1
• Time in Patent Office: 1,979 Days
• Field of Search: 378 2, 378 36, 378 62
• CPC Class Codes: A61B 6/032 Transmission computed tomography [CT]
• CPC Class Codes: A61B 6/40 Arrangements for generating radiation specially adapted for radiation diagnosis
• CPC Class Codes: A61B 6/4007 characterised by using a plurality of source units
• CPC Class Codes: A61B 6/405 Source units specially adapted to modify characteristics of the beam during the data acquisition process A61B6/4021, A61B6/4035 take precedence
• CPC Class Codes: A61B 6/4405 the apparatus being movable or portable, e.g. handheld or mounted on a trolley
• CPC Class Codes: A61B 6/484 involving phase contrast X-ray imaging
• CPC Class Codes: G01N 23/041 Phase-contrast imaging, e.g. using grating interferometers
• CPC Class Codes: G01V 5/22 Active interrogation, i.e. by irradiating objects or goods using external radiation sources, e.g. using gamma rays or cosmic rays
• CPC Class Codes: G01V 5/224 Multiple energy techniques using one type of radiation, e.g. X-rays of different energies
• CPC Class Codes: G21K 2207/005 Methods and devices obtaining contrast from non-absorbing interaction of the radiation with matter, e.g. phase contrast
• CPC Class Codes: H01J 2201/30449 Metals and metal alloys
• CPC Class Codes: H01J 2235/062 Cold cathodes
• CPC Class Codes: H01J 2235/068 Multi-cathode assembly
• CPC Class Codes: H01J 35/025 X-ray tubes with structurally associated circuit elements
• CPC Class Codes: H01J 35/04 Electrodes ; Mutual position thereof; Constructional adaptations therefor
• CPC Class Codes: H01J 35/045 Electrodes for controlling the current of the cathode ray, e.g. control grids
• CPC Class Codes: H01J 35/065 Field emission, photo emission or secondary emission cathodes
• CPC Class Codes: H01J 35/116 Transmissive anodes acting as a window H01J35/186
• CPC Class Codes: H01J 35/186 used as targets or X-ray converters

Abstract

Described here is a method for performing phase contrast imaging using an array of independently controllable x-ray sources. The array of x-ray sources can be controlled to produce a distinct spatial pattern of x-ray radiation and thus can be used to encode phase contrast signals without the need for a coded aperture. The lack of coded aperture increases the flexibility of the imaging method. For instance, because a fixed, coded aperture is not required, the angular resolution of the imaging technique can be increased as compared to coded-aperture imaging. Moreover, the lack of a radioopaque coded aperture increases the photon flux that reaches the subject, thereby increasing the attainable signal-to-noise ratio.

Claims

1. A method for phase contrast imaging using an array of independently controllable x-ray sources, the steps of the method comprising:

a) directing an array of independently controllable x-ray sources to produce x-ray radiation in a distinct spatial pattern by selectively energizing the independently controllable x-ray sources in the array;

b) detecting phase-contrast signals of the x-ray radiation after the x-ray radiation passes through a subject using an x-ray detector; and

c) reconstructing an image of the subject by performing a compressed sensing reconstruction technique on the detected phase-contrast signals, wherein the reconstructed image depicts an image contrast indicative of phase shifts in the x-ray radiation.

2. The method as recited in claim 1, in which each x-ray source of the array of independently controllable x-ray sources has a focal spot sized less than twenty micrometers.

3. The method as recited in claim 1, in which the x-ray detector is separated from the subject by at least one meter.

4. The method as recited in claim 1, in which the x-ray detector has an effective detector pitch of less than ten micrometers.

5. The method as recited in claim 1, in which the distinct spatial pattern is selected as at least one of a uniformly redundant array (URA) and a modified uniformly redundant array (MURA).

6. The method as recited in claim 1, in which step c) includes determining a target image, X, that minimizes an objective function defined as, ∥

Ψ

X∥

₁;

wherein Ψ

is a sparsifying transform that transforms the target image, X, into a sparse domain.

7. The method as recited in claim 6, in which the sparsifying transform is a discrete gradient transform.

8. The method as recited in claim 1, in which the subject is at least one of a human and an animal.

9. The method as recited in claim 1, in which the subject is at least one of a piece of luggage and a cargo container.

10. The method as recited in claim 9, in which the at least one of a piece of luggage and a cargo container includes an explosive, and the method further comprises identifying the explosive by analyzing the image reconstructed in step c).