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Fourier X-ray Scattering and Phase-Contrast Imaging: Enhanced Contrast and Sensitivity of X-ray Images

Posted Jun 02 2010 5:00pm

Description of Invention:
The invention offered for licensing is broadly applicable to medical diagnostic imaging, biological imaging, industrial non-destructive testing, security screening, and other routine x-ray inspections. The invention provides a method and apparatus that can significantly improve and enhance the contrast and sensitivity of x-ray images. More specifically, the method described in the invention provides a technique to obtain in a single shot x-ray diffraction, differential phase-contrast, as well as the conventional absorption images. X-ray diffraction reveals information about microscopic structures in the imaged object from nanometer to micrometer scales which enables detection of specific materials and disease pathologies that are invisible in conventional x-ray images. The main advantage of the invention over prior art is the single-shot capability without the need to scan an analyzer crystal or grating, and without the need for any hardware beyond standard radiography equipment. It also offers flexibility in hardware configuration to target specific materials by their diffraction signature. For this reason the invention is highly adaptable and well suited for day-to-day applications of x-ray radiography and computed tomography.

In one of the embodiments of the invention for example, a scattering imaging method uses a transmission grid to modulate the intensity of a beam of an x-ray radiation source. A detector captures a raw image from the modulated intensity pattern. A diffraction image can be automatically generated from the detected modulated intensity pattern.

In yet another embodiment, both a diffraction image and a differential phase-contrast image are obtained in a single exposure. Advantageously, commercially available x-ray grids and radiography machines can be used for this method, and exact positioning of the grid is unnecessary, as the method works for any non-zero distance between the grid and the detector. Thus, the speed and ease of implementation makes it suitable for both planar radiography and 3D computed tomography. In addition to its medical diagnostics significance, the invention can be utilized in other, non-medical applications such as non-destructive inspections and security screening.

  • Medical diagnostic radiography and computed tomography. For example, imaging blood vessels, imaging of bones (i.e., osteoporosis, fractures).
  • Non-invasive characterization of material microscopic structures by planar radiography or 3D computed tomography implementations of the invention.
  • Detection of materials by their diffraction signature in x-ray inspections and security screening.

Although x-ray diffraction and phase-contrast imaging can detect materials and structures that are invisible by conventional absorption images, current techniques remain difficult to implement due to requirements for specialized x-ray optical components and/or brilliant sources, and lengthy scanning of analyzer components such as perfect crystals or high-density gratings. A recent publication (US2007/0183563 A1) mentioned that by using a detector with elements less than 1/3 of the pitch of an analyzer grating, it is possible to obtain differential phase-contrast images in one measurement without the need to scan. US2007/0183580 A1 further elaborates on this technique and specifies that the detector elements are an integer fraction of the grating pitch so that sub-groups of the detectors can report x-ray intensities of different portions of a grating period, from which the phase shift of the grating pattern is measured. Such detectors are highly challenging to realize, and are not able to cope with varying pitches or patterns of x-ray beam modulation.

It is additionally known in the art to remove the effects of scattering with the use of grids, gratings, or other masks of periodically arranged opaque areas. Specifically, a mask or multiple masks of periodically arranged opaque areas are placed in the x-ray path, such that periodic dark shadows are created on a recorder surface either by direct geometric shadowing or by wave-interference effects. The shadow areas only receive x-ray which is scattered in the object. The signals of these shadow areas are subtracted from the raw image to yield an image free of the effects of scattering.

Nonetheless, the above variations require exacting procedures or are expensive, making the prior art ill-suited for today's routine x-ray imaging applications, including non-destructive testing (e.g., component inspection without damage), security screening, and medical diagnostic exams.

The present technology overcomes the drawbacks of the prior art by allowing the acquisition of x-ray diffraction, differential phase-contrast and absorption images all in a single exposure without the need for scanning or any hardware beyond commercial radiography equipment.

It is particularly flexible when compared to prior art in that the number of transmission grids, their patterns and their positions can all be adjusted to selectively detect or enhance specific materials, such as contrast agents in medical diagnostic imaging or explosive materials in security screening.

Development Status:
The invention is fully developed.

Han Wen (NHLBI)

Patent Status:
HHS, Reference No. E-248-2009/0
PCT, Application No. PCT/US2009/051642 filed 24 Jul 2009

Relevant Publication:
  1. H Wen, EE Bennett, MM Hegedus, S Rapacchi. Fourier X-ray scattering radiography yields bone structural information. Radiology 2009 Jun;252(3):910-918. [ PubMed: 19403849 ]
  2. H Wen, E Bennett, MM Hegedus, SC Carroll. Spatial harmonic imaging of X-ray scattering--initial results. IEEE Trans Med Imaging 2008 Aug;27(8):997-1002. [ PubMed: 18672418 ]

Licensing Status:
Available for licensing.

Collaborative Research Opportunity:
The National Heart, Lung, and Blood Institute, Laboratory of Cardiac Energetics, is seeking statements of capability or interest from parties interested in collaborative research to further develop, evaluate, or commercialize single-shot x-ray diffraction and phase-contrast imaging. Please contact Denise Crooks at 301-402-5579 or for more information.

Devices/Instrumentation - Diagnostics

For Additional Information Please Contact:
John Stansberry Ph.D.
NIH Office of Technology Transfer
6011 Executive Blvd. Suite 325,
Rockville, MD 20852
United States
Phone: 301-435-5236
Fax: 301-402-0220

Ref No: 2052

Updated: 06/2010

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