Aperture MTF Shaping for Grid Pattern Suppression
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Solution Overview
Problem
Existing radiation imaging apparatuses face challenges in effectively removing grid patterns, which can degrade image contrast and cause moire-like patterns due to the interaction between sampling pitch and grid density.
Innovation Solution
The apparatus incorporates a plurality of pixels with a photoelectric conversion element and a shielding layer that covers at least part of the aperture, adjusting the aperture modulated transfer function (MTF) to prevent the generation of grid patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a grid is used to remove scattered rays, then image contrast is improved, but grid patterns are generated that disturb the observer
Solution Approach 1:
The patent modifies the aperture shape parameter of the pixel to suppress grid patterns. By designing the aperture shape such that the aperture MTF has a minimum value at the grid pattern frequency, the periodic grid signal is attenuated while maintaining scattered ray removal capability through the grid structure.
Solution Approach 2:
The patent combines the grid structure with a specifically designed aperture shape to create a composite solution. The grid provides scattered ray removal while the aperture shape modification provides grid pattern suppression, achieving both objectives simultaneously.
2Object-affected harmful factors
If image processing is used to remove grid patterns, then grid pattern disturbance is reduced, but image processing complexity increases
Solution Approach 1:
The patent applies preliminary action by designing the aperture shape in advance to suppress grid patterns at the source. The aperture MTF is engineered to have minimum values at grid pattern frequencies before image acquisition, preventing grid pattern generation rather than requiring post-processing removal.
3Object-affected harmful factors
If the aperture shape is modified to suppress grid patterns, then grid pattern generation is prevented, but manufacturing precision requirements increase
Solution Approach 1:
The patent changes the aperture shape parameter to achieve grid pattern suppression. By optimizing the aperture MTF characteristics to have minimum values at grid pattern frequencies, the design achieves grid pattern reduction while the manufacturing precision requirement is managed through the specific functional requirement of the aperture shape.
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 configuration effectively prevents the generation of grid patterns, improving image contrast and reducing the occurrence of moire-like patterns by attenuating the aperture MTF at specific frequencies.
Implementation Method 1
a shielding layer covering the conversion element, wherein the shielding layer is provided to cover at least a part of an aperture of the conversion element
Implementation Method 2
digital radiography (DR) apparatuses that obtain radiological images using a photoelectric conversion element or the like made of a material such as a fluorescence body to convert an X-ray into visible light
Data Source
AI summary
An apparatus includes a plurality of pixels each including a conversion element, and a shielding layer covering the conversion element, wherein the shielding layer is provided to cover at least a part of an aperture of the conversion element so that an aperture modulated transfer function (MTF) at a predetermined frequency of a signal obtained from the conversion element becomes less than or equal to a predetermined value.