Radiographic Amplifier Current Matching for Artifact Reduction
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Solution Overview
Problem
Existing radiographic imaging apparatuses with automatic exposure control (AEC) functions face issues when a request to start emitting radiation is made during the acquisition of offset signals, leading to potential image artifacts and decreased image quality, as discussed in Japanese Patent Application Laid-Open No. 2020-89714 does not address this scenario effectively.
Innovation Solution
The apparatus includes detection pixels, correction pixels with lower radiation sensitivity, and imaging pixels, along with an amplification unit featuring a calculation amplifier with a feedback circuit and variable current supply capability. It performs detection and image acquisition operations during radiation emission, followed by offset signal acquisition and correction value determination before image acquisition, and adjusts the amplification unit's operation mode based on current supply capability during correction value acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the request to start emitting radiation is made during the acquisition of offset signals, then the radiation emission can start promptly, but image artifacts occur and image quality decreases
Solution Approach 1:
The patent applies dynamics by making the amplification unit's operation mode variable rather than fixed. The amplification unit can switch between first operation mode (during offset signal acquisition) and second operation mode (during image acquisition), allowing the system to adapt its amplification characteristics dynamically based on the current operational phase, thereby preventing image artifacts while maintaining prompt radiation emission response
Solution Approach 2:
The patent changes the amplification parameter of the amplification unit based on the operational phase. By adjusting the amplification parameter to a first value during offset signal acquisition and a second value during image acquisition, the system resolves the contradiction between prompt response and image quality, as the parameter change ensures proper signal handling in each phase without causing artifacts
2Device complexity
If the amplification unit operates in a fixed mode, then the circuit design is simple, but image artifacts occur when radiation emission starts during offset signal acquisition
Solution Approach 1:
The patent introduces dynamic operation modes for the amplification unit, transitioning from a fixed mode to a variable mode system. The control unit manages switching between first and second operation modes based on the acquisition phase, which adds control logic but eliminates image artifacts, thus improving reliability while maintaining reasonable circuit complexity
Solution Approach 2:
The amplification unit is designed to perform multiple functions by operating in different modes: it handles offset signal acquisition in the first mode and image acquisition in the second mode. This multi-functionality allows a single circuit design to reliably handle different operational requirements without causing artifacts, resolving the contradiction between simplicity and reliability
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 allows for accurate correction value determination and improved image quality by matching the amplification unit's operation modes, reducing image artifacts and enhancing the overall image grade even when the start request is received during offset signal acquisition.
Implementation Method 1
a calculation amplifier including a feedback circuit configured to amplify signals read from the plurality of pixels via a signal line
Implementation Method 2
a detection pixel configured to perform a detection operation for detecting an amount of emission of emitted radiation
Implementation Method 3
a correction pixel having a sensitivity to radiation lower than a sensitivity of the detection pixel to radiation and configured to correct the amount of emission in the detection operation
Implementation Method 4
an imaging pixel configured to acquire a radiographic image, and performs an image acquisition operation for reading a charge based on radiation accumulated in the imaging pixel
Data Source
AI summary
In a period between an operation for acquiring signals for an image via an amplification unit and an operation for acquiring offset signals for correcting the image via the amplification unit, a current supply capability of the amplification unit is made equal to a current supply capability in a period immediately before the image is acquired, thereby the potential state of a signal line when the signals for the image are acquired and the potential state when the offset signals for correcting the image are acquired are matched, and an artifact when the correction is made is reduced.