X-ray Interferometer Grating Stepping for 3D Dark Field Tomosynthesis
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Solution Overview
Problem
Current X-ray dark-field and phase-contrast imaging modalities suffer from longer acquisition times and limited quantitative capabilities due to mechanical movements and sensitivity gradients along the optical axis, resulting in 2D radiography that is insufficient for accurate diagnosis.
Innovation Solution
An X-ray imaging system with an interferometric arrangement where a grating is stepped laterally to generate stepping curves, combined with tomosynthesis-like movement of the X-ray source and detector, allowing for the reconstruction of 2.5D or 3D dark field, phase contrast, and attenuation image data without increasing acquisition time or radiation dose.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a two or three-grating interferometer is introduced into the X-ray beam to acquire dark field and phase contrast information, then the diagnostic accuracy for soft-tissue imaging is significantly increased, but the acquisition time becomes higher than for conventional chest radiography
Solution Approach 1:
The patent employs periodic action by implementing a stepping mechanism where the grating is moved in discrete steps across a limited range. For each step position, multiple images are acquired in rapid succession. This periodic stepping approach allows the system to collect sufficient data for dark field and phase contrast calculation while minimizing the total acquisition time through efficient sampling at each position.
Solution Approach 2:
The patent applies preliminary action by acquiring a complete set of images at each grating step position before moving to the next position. This ensures that all necessary data for calculating the three imaging signals (transmission, phase-contrast, and dark-field) is collected at each position, allowing for stable signal extraction and reducing the need for repeated measurements, thereby optimizing acquisition time.
2Measurement precision
If a two or three-grating interferometer is introduced into the X-ray beam to acquire dark field and phase contrast information, then the diagnostic accuracy for soft-tissue imaging is significantly increased, but the resulting image remains a 2D radiography with sensitivity gradient along the optical axis
Solution Approach 1:
The patent applies dimensionality change by introducing the grating stepping dimension perpendicular to the optical axis. By moving the grating laterally across multiple positions and acquiring images at each position, the system transforms the conventional 2D projection into a 2.5D or 3D data structure. This additional spatial dimension allows for sensitivity uniformity correction and enables quantitative analysis by accounting for the sensitivity gradient along the optical axis.
Solution Approach 2:
The patent implements feedback by using the acquired image sequence at different grating positions to calculate and correct for sensitivity variations. The system analyzes the stepping curve data to identify sensitivity gradients and applies corrections to generate quantitatively accurate images, ensuring that the final output compensates for the inherent sensitivity non-uniformity in the imaging system.
3Reliability
If significantly more images are recorded to allow for stable signal extraction in the stepping sequence, then the signal stability is improved, but the acquisition time increases further
Solution Approach 1:
The patent applies partial action by acquiring a sufficient but not excessive number of images at each grating step position. The system determines the minimum number of images required to achieve stable signal extraction for each of the three imaging signals, avoiding redundant acquisitions. This optimized sampling strategy ensures reliable signal extraction while minimizing acquisition time by not collecting more data than necessary.
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 enables the generation of more quantitative 2.5D or 3D image data, accounting for depth-dependent signal variations, while maintaining conventional radiography's acquisition time and avoiding additional radiation exposure.
Implementation Method 1
a two or three-grating interferometer is introduced into the X-ray beam, normally termed G0, G1 and G2 gratings
Implementation Method 2
gratings G1 and G2 are normally termed phase and analyzer gratings
Implementation Method 3
X-ray phase-contrast and dark-field imaging are two new imaging modalities that have shown the potential to significantly increase the diagnostic accuracy
Implementation Method 4
X-ray dark-field information could significantly help diagnose such pulmonary disorders as COPD or fibrosis
Data Source
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AI summary
The present invention relates to a system (10) for X-ray dark field, phase contrast and attenuation tomosynthesis image acquisition. The system comprises an X-ray source (20), an interferometer arrangement (30), an X-ray detector (40), a control unit (50), and an output unit. A first 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. The first axis extends through the examination region, and the examination region is configured to enable location of an objection to be examined. The interferometer arrangement is located between the X-ray source and the X-ray detector. The interferometer arrangement comprises a first grating (32) and a second grating (34). A second axis is defined that is perpendicular to a plane that is defined with respect to a centre of the first grating and/or a centre of the second grating. The control unit is configured to control movement of the X-ray source and/or movement of the X-ray detector to provide a plurality of image acquisition states, wherein the X-ray source and X-ray detector are configured to operate to acquire image data. For each of the plurality of image acquisition states the first axis extends through the examination region at a different angle. The control unit is configured to control movement of the first grating or movement of the second grating in a lateral position direction perpendicular to the second axis. For each of the acquisition states the first grating or second grating is at a different lateral position of a plurality of lateral positions. The output unit is configured to output one or more of: dark field image data, phase contrast image data, and attenuation image data.