Virtual Grating Phase Contrast Imaging
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Solution Overview
Problem
Phase contrast imaging techniques, particularly Coded Aperture Phase Contrast Imaging, face challenges with the need for an analyzing grating that must be adjusted relative to detector pixels, requiring high power x-ray sources to be replaced with low power tubes for longer exposure times, leading to inefficient use of radiation dose and increased quantum noise.
Innovation Solution
Implementing a virtual grid or grating that acts as a mask over pixel values, allowing certain pixels to be ignored or used in image computation, enabling the reuse of previously unused pixels to calculate absorption, phase, and dark field images, and shifting the beam splitter to increase resolution without mechanical movement of the grating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an analyzing grating is used in Coded Aperture Phase Contrast Imaging, then phase contrast image quality is improved, but the system complexity increases and mechanical adjustment is required
Solution Approach 1:
The patent creates a virtual copy of the analyzing grating by applying a virtual mask pattern to the detector pixels. Instead of using a physical grating that requires mechanical adjustment, the system digitally replicates the grating's function through software processing of the detector data, thereby maintaining image quality while reducing mechanical complexity
Solution Approach 2:
The patent replaces the mechanical analyzing grating system with a digital virtual grating implemented through pixel masking and image processing algorithms. This substitution eliminates the need for physical grating movement and alignment mechanisms while achieving the same phase contrast imaging function
2Measurement precision
If an analyzing grating is used, then phase contrast information is obtained, but radiation dose is wasted and exposure time increases
Solution Approach 1:
The virtual grating approach allows full utilization of the incident radiation by digitally processing the complete detector data. Unlike physical gratings that block and waste radiation, the virtual mask processes all detected photons through computational algorithms, extracting phase contrast information without wasting radiation dose
Solution Approach 2:
The patent maintains continuous useful action by processing all detected radiation through the virtual grating system. The virtual mask ensures that every detected photon contributes to the final image, eliminating the interruptions and waste associated with physical grating transmission and reflection losses
3Measurement precision
If an analyzing grating is used, then beamlet direction changes are detected, but mechanical movement and alignment are required
Solution Approach 1:
The patent replaces the mechanical analyzing grating with a virtual grating implemented through digital image processing. The virtual mask pattern is applied to detector pixels through software, eliminating all mechanical movement and alignment requirements while maintaining the ability to detect beamlet direction changes and phase contrast information
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 reduces the need for mechanical adjustments, allows the use of high power x-ray sources for shorter exposure times, and effectively utilizes the entire radiation dose, resulting in improved image resolution and reduced quantum noise.
Implementation Method 1
The emitted radiation beam is split up in so-called beamlets by means of a physical beam splitter or beam splitting grating (also called coded aperture) which blocks part of the radiation beam
Implementation Method 2
Implementing a virtual grid or grating that acts as a mask over pixel values, allowing certain pixels to be ignored or used in image computation
Implementation Method 3
at least one radiation image of an object is generated and recorded by means of a radiation detector such as a direct or in-direct radiography detector
Data Source
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Figure 3~4
AI summary
A phase contrast imaging (PCI) method in which instead of using an analyzer grid detector pixels are grouped and only a part of the total pixels are used to calculate a phase contrast image. In a second, third... step the pixels which were not used in the previous recalculation are used additionally to recalculate a second, third... phase contrast image. Finally the different phase contrast images are fused to result in a full image.