Phase Contrast X-ray Imaging System Moire Artifact Reduction
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Solution Overview
Problem
Phase contrast X-ray imaging systems using Talbot-Lau interferometers face challenges in reducing moire artifacts due to shifts between set and actual grating movements, which affect the accuracy of phase contrast images, especially when thermal variations or movement inaccuracies cause misalignment between gratings.
Innovation Solution
A phase contrast X-ray imaging system and method that involves an X-ray source, multiple gratings, and a grating movement mechanism, where a controller analyzes the period of intensity changes in pixel values to adjust the set values of grating movement, thereby reducing moire artifacts by aligning the actual movement with the set movement, using the analysis period to correct for shifts and improve image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fringe scanning method is used to generate phase contrast images, then phase contrast imaging capability is achieved, but moire artifacts appear due to shifts between set and actual grating movements
Solution Approach 1:
The system measures the actual grating position using interference fringe patterns and feeds back this information to correct the set position values. The controller calculates position correction amounts based on the phase differences between adjacent pixels in the interference fringe patterns, and applies these corrections to reduce moire artifacts in the final phase contrast images.
Solution Approach 2:
The system dynamically adjusts the set position parameters of the gratings based on measured actual positions. By changing the position parameters from fixed set values to corrected values derived from actual measurements, the system eliminates the mismatch between intended and actual grating positions, thereby reducing moire artifacts.
2Adaptability or versatility
If thermal variation or movement accuracy issues cause shifts in grating positions, then the imaging system remains operational, but the period of intensity change deviates from the grating pattern period
Solution Approach 1:
The system performs preliminary measurement of the actual grating positions using interference fringe patterns before generating the final phase contrast images. This preliminary action allows the system to detect position deviations caused by thermal variation or movement inaccuracies and correct them in advance, ensuring accurate period measurement throughout operation.
Solution Approach 2:
The system continuously monitors grating positions through interference fringe analysis and provides feedback to correct position deviations. This feedback mechanism maintains measurement precision even when thermal variation or movement accuracy issues cause shifts in grating positions during operation.
3Object-affected harmful factors
If approximation is applied to intensity change data when grating position shifts occur, then some artifact reduction is achieved, but significant moire artifacts remain when shifts are large
Solution Approach 1:
Instead of relying on approximation methods, the system uses feedback from actual position measurements to determine the true grating positions. This measured position information is used to accurately reconstruct the intensity change patterns, eliminating the need for approximation and effectively reducing moire artifacts even when position shifts are significant.
Solution Approach 2:
The system replaces mechanical approximation methods with optical measurement and computational correction. By using interference fringe patterns to measure actual positions and computationally correcting the data based on these measurements, the system achieves superior artifact reduction compared to mechanical approximation approaches.
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
The system effectively reduces moire artifacts in phase contrast images even when significant shifts occur between set and actual grating movements, enhancing image accuracy and visibility by adjusting the grating movement parameters based on acquired analysis periods.
Implementation Method 1
Phase contrast X-ray imaging systems for capturing an image using a plurality of gratings are known in the art. Such a phase contrast X-ray imaging system is disclosed in Japanese Patent Publication No. JP6743983, for example. The phase contrast X-ray imaging system disclosed in the above Japanese Patent Publication No. JP6743983 performs X-ray imaging using a Talbot-Lau interferometer
Implementation Method 2
a second grating for interfering with the self-image of the first grating
Data Source
AI summary
A phase contrast X-ray imaging system includes an X-ray source, a plurality of gratings, a detector for detecting X-rays, a grating movement mechanism, and a controller. The controller generates a phase contrast image based on intensity changes that represent changes in pixel values of pixels detected by the detector while moving a scanning grating, which is at least one of the plurality of gratings, using the grating movement mechanism. The controller acquires an analysis period representing a period of the intensity change to reduce a moire artifact, and adjusts a set value of movement of the scanning grating for generating the phase contrast image based on the analysis period acquired.