X-ray Detector Pixel Depletion Voltage Control
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Solution Overview
Problem
X-ray detectors, particularly direct converting quantum-counting detectors, experience spatial inhomogeneity and short-term 'drift' due to factors like radiation history and temperature changes, leading to inconsistent detector response and reduced image quality, which current compensation methods only partially address with increased costs.
Innovation Solution
Individual adjustment of depletion voltages for each pixel electrode to align effective pixel sizes and dynamically adjust these voltages based on X-ray radiation intensity and history, distinguishing between 'spectral squeezing' and 'pixel size drift' to prevent pixel size drift at its emergence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional reference image compensation is used, then static spatial inhomogeneity is corrected, but short-term drift cannot be compensated and production/operating costs increase
Solution Approach 1:
The invention changes the electrical parameter (depletion voltage) of each pixel electrode dynamically to compensate for drift. By adjusting the depletion voltage individually for each pixel based on measured drift characteristics, the system corrects detector response variations without requiring complex hardware modifications or increased production costs.
Solution Approach 2:
The system implements a feedback mechanism where the actual detector response is measured, drift is detected, and depletion voltages are adjusted accordingly. The control unit continuously monitors pixel responses and modifies depletion voltages to maintain consistent detector performance, enabling real-time compensation of short-term drift.
2Ease of manufacture
If depletion voltage is uniformly applied to all pixel electrodes, then system simplicity is maintained, but spatial inhomogeneity and drift occur
Solution Approach 1:
The invention applies different depletion voltages to different pixel electrodes based on their individual characteristics and drift behavior. Each pixel electrode receives a locally optimized voltage that compensates for its specific drift tendency, achieving high response stability without compromising manufacturing simplicity since the voltage adjustment is done electronically rather than through physical modifications.
3Manufacturing precision
If individual depletion voltages are applied to each pixel electrode, then pixel size drift is eliminated, but control complexity increases
Solution Approach 1:
The system transitions from static uniform depletion voltage to dynamic individualized voltage control. The depletion voltages are adjusted in real-time based on measured drift characteristics, allowing the system to adapt to changing conditions and maintain pixel size uniformity despite variations in operating conditions, radiation history, or temperature.
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
Significantly improves image quality by eliminating pixel size drift and reducing overall detector response variability, enhancing signal stability and reproducibility without significant increases in production or operating costs.
Implementation Method 1
An X-ray detector of this kind conventionally has an X-ray sensitive sensor layer in which electron-hole pairs are generated by incident X-ray quanta
Implementation Method 2
Under the effect of the depletion voltage, typically on the order of magnitude of 1,000 volts, the 'knocked out' electrons drift, due to an X-ray quantum, to one of the pixel electrodes and activate a current pulse there
Data Source
AI summary
In a method and control unit for activating an X-ray detector, having an X-ray sensitive sensor layer and an arrangement of pixel electrodes connected at the back to the sensor layer, an individually adjusted depletion voltage is applied to each of the pixel electrodes. The value of the depletion voltages applied to different pixel electrodes is chosen to be different such that the effective pixel sizes respectively associated with the pixel electrodes are aligned with each other.