Glancing Angle Grating Interferometer for High-Energy X-Ray Phase Contrast
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Solution Overview
Problem
Conventional X-ray differential phase contrast (DPC) imaging methods face challenges in achieving efficient phase contrast imaging with high energy X-rays due to difficulties in fabricating micron-period absorption gratings required for higher energy X-rays, limiting contrast and practical applications, especially in medical and industrial settings.
Innovation Solution
A method using a multi-sector source grating, beam-splitter grating, and analyzer grating interferometer, where the object is positioned between the beam-splitter and analyzer gratings, allowing for multiple image acquisition during a single exposure with varying interferometer phasing, and combining these images to produce a phase contrast image, enabling efficient phase contrast imaging over a broad energy range, including high energy X-rays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional absorption gratings are used for high energy X-rays, then phase contrast imaging can be achieved, but the grating fabrication becomes extremely difficult and contrast is limited
Solution Approach 1:
The patent changes the fundamental parameter of grating operation from normal incidence to glancing angle incidence. This parameter change allows the use of much thinner grating structures (overcoming fabrication difficulties) while maintaining effective phase contrast imaging at high X-ray energies through the enhanced path length interaction at glancing angles.
Solution Approach 2:
The patent employs composite grating structures combining absorbing materials (such as gold or tungsten) with supporting substrate materials. This composite approach enables the creation of thin, fragile absorbing elements that can be fabricated at glancing angles without requiring deep, complex groove structures, thus resolving the fabrication difficulty while maintaining imaging quality.
2Adaptability or versatility
If normal incidence grating interferometers are used, then phase contrast imaging is achievable, but the system is limited to lower X-ray energies due to fabrication constraints
Solution Approach 1:
The patent changes the incidence angle parameter from normal to glancing angle, which fundamentally alters the interaction between X-rays and the grating structure. This enables the system to operate effectively across a broad energy range including high energies, as the glancing angle geometry reduces the required grating thickness and relaxes fabrication constraints.
Solution Approach 2:
The patent introduces a new dimensional approach by tilting the grating planes to glancing angles relative to the X-ray beam. This dimensional change in the grating orientation enables high energy X-ray phase contrast imaging without requiring the deep, complex structures that would be needed at normal incidence, thus expanding energy range coverage.
3Measurement precision
If multiple sequential exposures are used for phase stepping, then phase contrast information can be extracted, but imaging time increases and productivity decreases
Solution Approach 1:
The patent employs periodic modulation of the grating positions to create phase-stepped interference patterns. By using multiple gratings with different fixed phase offsets (rather than sequential stepping), the system captures phase information simultaneously in a single exposure, maintaining measurement precision while dramatically improving imaging speed and productivity.
Solution Approach 2:
The patent pre-configures multiple gratings with different phase offsets before the exposure is made. This preliminary arrangement of gratings allows all phase steps to be captured simultaneously in one exposure, eliminating the need for sequential stepping during the exposure and thus maintaining accurate phase contrast measurement while improving imaging throughput.
4Use of energy by moving object
If crystal optics are used for DPC imaging, then high intensity X-rays can be utilized, but the system is limited to synchrotron sources and cannot work with conventional X-ray tubes
Solution Approach 1:
The patent changes the optical interaction parameter from the extreme precision required by crystal diffraction to the more tolerant grating-based phase modulation at glancing angles. This parameter change allows the system to work with conventional X-ray tube sources that have lower intensity and broader spectral width, greatly expanding source compatibility while still utilizing X-ray energy effectively.
Solution Approach 2:
The patent replaces expensive, complex crystal optics with simpler, more robust grating structures that can be fabricated using standard microfabrication techniques. This substitution enables the use of conventional, inexpensive X-ray tube sources instead of requiring expensive synchrotron facilities, making the system adaptable to a wide range of source types including portable and clinical X-ray systems.
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 high-resolution, clinically compatible dose, and scanning speed phase contrast imaging of large objects, enhancing soft tissue contrast and spatial resolution, suitable for medical and industrial applications, and overcoming the limitations of conventional grating shearing methods at higher energies.
Implementation Method 1
X-ray differential phase-contrast (DPC) imaging relies on the refraction of the X-rays passing through an object
Implementation Method 2
the basic technique used for DPC imaging is to angularly filter with μ-radian resolution the transmitted X-ray beam, thus converting the angular beam deviations from refraction into intensity changes
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
A differential phase contrast X-ray Imaging system includes an X-ray illumination system, a beam splitter arranged in a radiation path of the X-ray illumination system, and a detection system arranged in a radiation path to detect X- rays after passing through the beam splitter.