X-ray Phase Contrast Imaging Using Spectrally Resolving Detector
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Solution Overview
Problem
Existing X-ray devices struggle to generate phase contrast images with sufficient spatial resolution due to the large pixel size of detectors relative to the distance between interference pattern maxima and minima, requiring complex mechanical movements that are challenging to perform quickly and accurately, especially in medical imaging applications.
Innovation Solution
An X-ray device with a diffractive optical element and a spectrally resolving detector that uses polychromatic X-ray sources and a modulator to enhance spatial resolution, allowing for simultaneous measurement of interference patterns at different energies or wavelengths, eliminating the need for mechanical modulation of gratings and enabling efficient phase contrast imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an absorption grating is used to resolve interference patterns with detector pixels, then spatial resolution is improved, but device complexity and mechanical precision requirements increase significantly
Solution Approach 1:
The patent replaces the mechanical grating shifting system with a computational approach. Instead of physically moving the absorption grating to sample different portions of the interference pattern, the system uses the detector to directly capture the full interference pattern and applies digital signal processing to extract phase information. This substitution eliminates complex mechanical positioning requirements while maintaining spatial resolution capability.
Solution Approach 2:
The patent transitions from spatial sampling in one dimension (shifting the grating laterally) to spectral/energetic discrimination. By using an energy-resolving detector that can distinguish different X-ray photon energies, the system extracts phase information through the energy dimension rather than through mechanical spatial displacement, thereby avoiding the mechanical complexity.
2Measurement precision
If mechanical movement of gratings is implemented for phase contrast imaging, then phase shift measurement is enabled, but speed and accuracy of imaging deteriorate due to mechanical limitations
Solution Approach 1:
The patent eliminates the mechanical grating movement mechanism entirely by using an energy-resolving detector to capture the interference pattern at a fixed geometry. The phase shift information is extracted through energy-dependent analysis of the interference pattern rather than through mechanical displacement, enabling rapid imaging without mechanical inertia or positioning errors.
Solution Approach 2:
The patent performs the interference pattern capture and phase extraction in a single simultaneous operation using the energy-resolving detector. Instead of requiring sequential mechanical movements to sample the pattern at different positions, the system captures all necessary information in one exposure and processes it computationally, achieving preliminary completion of the measurement task.
3Stability of the object's composition
If monochromatic X-ray sources are used for interference pattern generation, then coherence is improved, but source utilization efficiency deteriorates due to limited bandwidth usage
Solution Approach 1:
The patent changes the approach from selecting a narrow energy band (monochromatic) to utilizing the full polychromatic spectrum. By using an energy-resolving detector, the system can process interference patterns generated across a broad X-ray energy range, transforming the previously harmful spectral diversity into a useful dimension for extracting phase information while improving source efficiency.
Solution Approach 2:
The patent applies energy-dependent analysis to different portions of the interference pattern. By analyzing how the interference pattern varies with photon energy, the system can extract phase information at different energy levels, effectively using the local quality (energy specificity) of different X-ray photons to enhance the overall measurement rather than requiring uniform monochromatic illumination.
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 allows for fast and efficient generation of phase contrast images with improved spatial resolution, suitable for medical imaging, by leveraging polychromatic X-ray sources and energy-resolving detectors, reducing mechanical complexity and optimizing X-ray source usage.
Implementation Method 1
a diffractive optical element, which will be abbreviated 'DOE' in the following. The DOE is exposed to the X-ray source, i.e. it is disposed such that it is hit by the emission of the X-ray source if the latter is active
Implementation Method 2
A spectrally resolving X-ray detector for detecting an interference pattern generated by the DOE
Data Source
Figure 1
AI summary
The invention relates to a method and a device for generating phase contrast X-rayimages of an object (1). The device comprises an X-raysource (10) that may for example be realized by a spatiallyextended emitter (11) behind a grating (G0 ). A diffractive optical element (DOE), for example a phase grating(G 1 ), generates an interference pattern(I) from the X-radiation that has passed the object (1), and a spectrally resolving X-ray detector (30) is used to measure this interference pattern behind the DOE. Using the information obtained for different wavelengths/energies of X-radiation, the phase shift induced by the object can be reconstructed.