X-ray Grating Vibration for Phase Contrast Imaging
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Solution Overview
Problem
Conventional X-ray imaging systems face challenges in achieving high contrast between tissue types, requiring high X-ray doses or contrast agents, and struggle with vibration-induced blurring in grating-based phase-contrast and dark-field imaging, which complicates calibration and increases acquisition time.
Innovation Solution
An X-ray imaging system with an interferometric arrangement that allows gratings to move during image acquisition, using vibration transducers to introduce controlled vibrations and low-pass filtering to wash out Moiré fringes, enabling continuous data acquisition and calibration without removing gratings from the beam path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gratings are kept stationary during image acquisition, then Moiré fringes are preserved for phase-contrast and dark-field imaging, but the system is sensitive to vibrations and requires long acquisition times with multiple repositioning steps
Solution Approach 1:
The patent applies the dynamics principle by intentionally moving the gratings during image acquisition instead of keeping them stationary. The grating movement is controlled to occur at a speed that prevents Moiré fringe formation, thereby eliminating vibration sensitivity and enabling continuous acquisition without repositioning steps, which resolves the contradiction between image quality and acquisition time.
Solution Approach 2:
The patent implements periodic action by using a vibration transducer to apply controlled oscillations to the gratings during acquisition. This periodic movement ensures that the gratings never remain stationary long enough to form Moiré fringes, while the oscillations are controlled to maintain image quality, thus eliminating the need for multiple repositioning steps and reducing acquisition time.
2Measurement precision
If gratings are removed from the beam path for calibration, then accurate attenuation data can be acquired, but the system complexity increases and calibration time is lost
Solution Approach 1:
The patent applies continuity of useful action by acquiring calibration data continuously during grating movement without removing the gratings from the beam path. The system accumulates calibration information throughout the grating traversal, eliminating the need for separate calibration steps and reducing overall system complexity while maintaining measurement precision.
Solution Approach 2:
The patent implements preliminary action by collecting calibration data during the grating movement process itself, before any repositioning or removal operations. This allows calibration to be performed as part of the normal acquisition sequence, eliminating additional calibration steps and reducing system complexity.
3Measurement precision
If multiple stepping steps are used to acquire phase-contrast and dark-field images, then diagnostic accuracy is improved, but acquisition time increases and vibration sensitivity increases
Solution Approach 1:
The patent applies the skipping principle by rapidly moving the gratings through the measurement range in a continuous motion that prevents Moiré fringe formation. This allows the system to acquire all necessary information for phase-contrast and dark-field imaging in a single continuous pass rather than requiring multiple discrete stepping steps, thereby improving acquisition speed while maintaining diagnostic accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces X-ray exposure, minimizes acquisition time, and allows for accurate calibration data acquisition while maintaining image quality, tolerating external vibrations and eliminating the need for grating repositioning, thus enhancing diagnostic accuracy.
Implementation Method 1
The control unit is configured to control the at least one vibration transducer to vibrate the first grating and/or second grating. An amplitude of vibration is greater than or equal to the period of the first grating and/or second grating.
Implementation Method 2
Using an analyzer grating with the same periodicity, a Moiré-pattern can be measured with the detector.
Implementation Method 3
For the acquisition of these new imaging modalities a two or three-grating interferometer is introduced into the X-ray beam
Implementation Method 4
Conventional linear attenuation X-ray systems and conventional computed tomography (CT) measure the linear attenuation coefficient of objects.
Data Source
Figure 1
Figure 2a~3
Figure 4a~4j
AI summary
The present invention relates to a system (1010) for X-ray dark field, phase contrast and attenuation image acquisition, the system comprising: an X-ray source (1020); an interferometer arrangement (1030); an X-ray detector (1040); a control unit (1050); at least one vibration transducer (1080); a processing unit (1090); and an output unit (1060). An axis is defined extending from a centre of the X-ray source to a centre of the X-ray detector. An examination region is located between the X-ray source and the X-ray detector, wherein the axis extends through the examination region, and wherein the examination region is configured to enable location of an object to be examined. The interferometer arrangement is located between the X-ray source and the X-ray detector, and wherein the interferometer arrangement comprises a first grating (1032) and a second grating (1034). For a first mode of operation: The control unit is configured to control at least one lateral movement transducer (1070) to move the first grating or move the second grating in a lateral position direction perpendicular to the axis. The control unit is configured to control the X-ray detector to acquire image data whilst the first grating and/or second grating is moving. During an exposure time of the X-ray detector the first grating and/or second grating has moved a distance less than a period of the first grating and/or second grating. The control unit is configured to control movement of the first grating and/or second grating such that the image data is acquired whilst the first grating and/or second grating is moving. The output unit is configured to output one or more of: dark field image data, phase contrast image data, and attenuation image data; For a second mode of operation: The control unit is configured to control the X-ray detector to acquire each image data of a plurality of image data whilst the first grating and/or second grating is moving during an exposure time of the X-ray detector. The control unit is configured to control the at least one vibration transducer to vibrate the first grating and/or second grating. An amplitude of vibration is greater than or equal to the period of the first grating and/or second grating. The processing unit is configured to generate attenuation image data and/or calibration data comprising a determination of a temporal low-pass filtered version of at leas some of the plurality of image data. The output unit is configured to output the attenuation image data and/or the calibration data.