Radiation Imaging Grid Pixel Pairing for Accurate Exposure Control
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Solution Overview
Problem
Existing radiation imaging apparatuses with automatic exposure control (AEC) suffer from inaccuracies due to a disproportionate influence on radiation detection pixels caused by X-ray absorption layers of the grid, leading to discrepancies between the average dose of radiation in the region of interest and detected signals.
Innovation Solution
The apparatus employs a configuration where radiation detection pixels are arranged in pairs to cancel out the influence of X-ray absorption layers, using specific equations to determine optimal pixel positions based on grid density and pitch, ensuring accurate automatic exposure control by averaging signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a grid with X-ray absorption layers is used to remove scattered rays, then scattered ray removal is improved, but a disproportionate influence on radiation detection pixels occurs due to overlap between absorption layers and pixels
Solution Approach 1:
The detection pixels are segmented into multiple regions, with specific pixels designated as dose detection pixels positioned to overlap with grid absorption layers. This segmentation allows the system to distinguish between pixels affected by grid attenuation and those that are not, enabling accurate dose measurement despite the presence of the grid.
Solution Approach 2:
Different pixels are assigned different functions based on their positional relationship with the grid. Dose detection pixels are specifically positioned to overlap with absorption layers to measure attenuated dose, while other pixels capture the actual image. This local differentiation allows the system to compensate for grid effects in dose measurement while maintaining image quality.
2Object-affected harmful factors
If radiation detection pixels overlap with X-ray absorption layers of the grid, then scattered ray removal is improved, but signals of radiation detection pixels become disproportionately influenced by grid attenuation
Solution Approach 1:
The system uses the signals from dose detection pixels that overlap with grid absorption layers as feedback to calculate and compensate for grid attenuation effects. By measuring the dose through the grid at specific pixel locations, the system can determine the attenuation characteristics and apply corrections to achieve accurate automatic exposure control.
Solution Approach 2:
The arrangement of dose detection pixels is intentionally asymmetric with respect to the grid structure, with pixels positioned at specific locations where they overlap with absorption layers. This asymmetric positioning allows the system to capture the grid's attenuation effect in a controlled manner, enabling accurate dose measurement and compensation.
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 arrangement significantly improves the accuracy of automatic exposure control by reducing the influence of grid attenuation on detection pixels, ensuring precise dose measurement and emission control.
Implementation Method 1
a photoelectric conversion element that converts the light into an electrical signal
Implementation Method 2
a scintillator that generates light when radiation is incident thereon
Implementation Method 3
an X-ray absorption layer and an X-ray transmissive layer each having a strip shape are alternately arranged
Data Source
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AI summary
A radiation imaging apparatus for performing radiography using a grid in which a radiation transmissive layer and a radiation absorption layer each having a strip shape and extending in a first direction are alternately arranged in a second direction, the radiation imaging apparatus includes a pixel unit including a plurality of imaging pixels and a plurality of detection pixels, wherein the plurality of detection pixels includes a first detection pixel and a second detection pixel that are in a pair in the second direction, an output signal value of the first detection pixel is larger than an average value of output signal values of the plurality of imaging pixels and the plurality of detection pixels, and an output signal value of the second detection pixel is smaller than the average value.