Radiation Imaging Pixel Timing Synchronization
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Solution Overview
Problem
Existing radiation imaging apparatuses face challenges in capturing accurate energy-subtracted images of moving objects due to variations in the time interval between radiation exposure and signal sampling, leading to inconsistencies in energy and dose between frames, which degrade the accuracy of energy subtraction and cause artifacts in moving images.
Innovation Solution
The implementation of a radiation imaging apparatus that synchronizes the start of signal sampling and holding with the actual radiation emission, using a detection unit to generate synchronization signals for precise timing of sample and hold operations, ensuring consistent periods from radiation start to signal sampling across frames, thereby reducing variations and improving image accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the tube voltage is changed between first kV value and second kV value for dual energy imaging, then energy subtraction capability is improved, but the time from X-ray exposure to signal transfer varies between frames causing inconsistency in energy and dose
Solution Approach 1:
The patent applies preliminary action by resetting the conversion element to a predetermined state before each radiation exposure. This ensures that each frame starts from a known baseline condition, eliminating carryover effects from previous frames and ensuring consistent energy and dose measurements across all frames during dual energy imaging sequences.
Solution Approach 2:
The patent implements feedback by using a sample and hold node that captures and holds the integrated signal at a specific timing point. This held signal is then transferred to a storage node, creating a feedback mechanism that ensures consistent sampling timing across frames. The timing control unit coordinates the reset, integration, and transfer operations to occur at consistent intervals, maintaining reliability of energy and dose measurements.
2Productivity
If multiple frames are captured by performing X-ray exposure multiple times, then moving image capability is improved, but variations in timing cause artifacts in the captured images
Solution Approach 1:
The conversion element is reset to a predetermined state before each frame's radiation exposure, ensuring consistent starting conditions for each frame. This preliminary reset action eliminates accumulated signals from previous frames, preventing artifacts while maintaining high frame rate capability for moving image capture.
Solution Approach 2:
The patent implements periodic action through synchronized, repeating cycles of radiation exposure, signal integration, and transfer operations. The timing control unit ensures that each frame follows the same periodic sequence with consistent timing intervals, which eliminates timing variations that would cause artifacts in moving images while maintaining high productivity.
3Speed
If the time interval for capturing multiple radiation images is reduced to capture fast moving objects, then speed of capturing moving objects is improved, but the object moves during exposure causing movement artifacts
Solution Approach 1:
The patent maintains continuity of useful action by implementing overlapping integration periods where the conversion element continuously integrates signals during radiation exposure without interruption. This continuous integration, combined with synchronized timing control, allows for very short exposure intervals necessary for capturing fast moving objects while maintaining image quality without movement artifacts.
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 enhances the accuracy of energy subtraction and reduces artifacts in moving images by maintaining consistent energy and dose across frames, improving the overall quality of radiation images obtained through the energy subtraction method.
Implementation Method 1
Each of the plurality of pixels includes a conversion element for converting radiation into an electric signal
Data Source
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AI summary
A radiation imaging apparatus includes a pixel array including a plurality of pixels, a readout circuit configured to read out signals from the pixel array, a detection unit configured to detect, based on radiation emitted from a radiation source or information provided from the radiation source, a start of irradiation of radiation by the radiation source, and a control unit configured to determine a timing of each of a plurality of sample and hold operations in each of the plurality of pixels each time the start of irradiation of radiation is detected by the detection unit. The timing of at least one sample and hold operation of the plurality of sample and hold operations is a timing in a radiation irradiation period, and each of the plurality of pixels includes a conversion element configured to convert radiation into an electrical signal, and a sample and hold circuit configured to sample and hold the signal from the conversion element over a plurality of times in accordance with the timing of each of the plurality of sample and hold operations determined by the control unit.