Grating-Based Differential Phase Contrast X-Ray Imaging System
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Solution Overview
Problem
Conventional medical X-ray imaging struggles with soft tissue differentiation due to low contrast, as existing phase contrast imaging techniques require sensitive mechanical alignment and specific X-ray sources, limiting their clinical applicability.
Innovation Solution
A grating-based differential phase contrast imaging system with controllable Moiré frequency patterns, achieved by adjusting the dimensions of source, phase, and absorption gratings, allowing for optimized alignment and contrast without the need for precise positioning of the phase and absorption gratings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional phase contrast imaging techniques are used to achieve high soft tissue contrast, then imaging sensitivity is improved, but mechanical alignment precision and system complexity increase
Solution Approach 1:
The patent changes the key parameter from grating alignment precision to Moiré frequency control. By adjusting the Moiré frequency through source grating dimension selection rather than precise mechanical alignment, the system achieves high soft tissue contrast while reducing alignment complexity
Solution Approach 2:
The patent replaces the mechanical alignment system with an optical parameter control system. Instead of mechanically aligning gratings to high precision, the system uses Moiré frequency patterns generated by controlled grating dimensions to achieve the desired contrast
2Manufacturing precision
If precise positioning of phase and absorption gratings is implemented to optimize contrast, then imaging quality is improved, but system complexity and manufacturing difficulty increase
Solution Approach 1:
The patent performs preliminary selection of source grating dimensions before system assembly. By pre-calculating and selecting gratings with specific dimensions that produce the desired Moiré frequency, the system eliminates the need for complex post-assembly alignment adjustments
Solution Approach 2:
The patent shifts the precision requirement from positional parameters (grating locations) to dimensional parameters (grating periods). This allows standard manufacturing tolerances to be used while achieving optimal contrast through controlled grating dimensions
3Measurement precision
If Moiré frequency is controlled by adjusting phase and absorption grating dimensions, then imaging contrast is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent inverts the traditional approach by not trying to eliminate Moiré patterns but rather controlling their frequency. By accepting and controlling the Moiré frequency rather than attempting to eliminate it through ultra-precise manufacturing, the system achieves practical manufacturing tolerances while maintaining high contrast
4Ease of manufacture
If conventional X-ray sources are used with interferometric imaging, then system cost is reduced, but image contrast for soft tissues deteriorates
Solution Approach 1:
The patent changes the imaging parameter from absorption-based to phase-contrast-based detection using Moiré frequency patterns. This allows conventional X-ray sources to be used while achieving high soft tissue contrast through the phase modulation detected by the controlled Moiré patterns
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 provides enhanced imaging contrast and sensitivity by controlling the Moiré frequency, enabling better differentiation of soft tissues and maintaining system performance across varying X-ray spectra.
Implementation Method 1
A Moiré fringe pattern frequency and angular orientation produced in the plane of the X-ray detector D of the DPCI system 100 is a function of the gratings' axial rotation about the axis z
Implementation Method 2
Phase grating G1 may have a period p1 of about a few micrometers, which is less than p0, and generates a self-imaging interference pattern 106
Implementation Method 3
Such a system takes advantage of the Talbot self-imaging interferometric effect to detect local phase shifts in the imaged object
Implementation Method 4
a partially absorbing grating G2 (absorption grating), and an X-ray detector D which captures a radiographic image of an object 105
Data Source
AI summary
A method for assembling a phase contrast x-ray imaging system includes fabricating a phase grating and an absorption grating according to a preselected pitch of the gratings. The actual obtained pitches are measured and a source grating is then fabricated according to a desired design point of the imaging system.