Radiation Detector Reference Pixels for Charge Sharing Correction
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Solution Overview
Problem
Direct-conversion semiconductor radiation detectors face challenges with charge cloud spreading across multiple pixels, leading to erroneous measurements due to charge sharing, which affects the accuracy of X-ray imaging and energy discrimination.
Innovation Solution
Incorporating reference pixels between primary pixels, sized to prevent charge cloud overlap, and employing coincidence circuitry to accurately associate signals from reference and primary pixels, allowing for spectral correction and sub-pixel resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct-conversion semiconductor detectors are used to detect X-ray photons, then detection efficiency is improved, but charge cloud spreading causes measurement errors due to charge sharing between pixels
Solution Approach 1:
The detector surface is divided into discrete pixels with well-defined boundaries, and the readout electronics are segmented to independently process signals from each pixel. This segmentation allows precise localization of charge clouds and attribution of shared charge to specific pixels, resolving the measurement accuracy issue while maintaining detection efficiency.
Solution Approach 2:
Different regions of the detector are assigned different functions: some pixels are optimized for high-efficiency detection while others incorporate charge-sharing correction capabilities. The readout electronics apply local correction algorithms based on the spatial distribution of charge signals, improving measurement precision without sacrificing overall detection efficiency.
2Reliability
If pixel size is increased to improve signal strength, then detection sensitivity is improved, but charge cloud overlap between adjacent pixels increases
Solution Approach 1:
The readout electronics monitor the charge signals from adjacent pixels and apply feedback correction when charge sharing is detected. By analyzing the signal distribution across multiple pixels and using coincidence detection, the system can identify charge-sharing events and correct the measured values, maintaining measurement precision even with larger pixel sizes that improve signal strength.
3Measurement precision
If energy discrimination is implemented to improve material delineation, then imaging quality is improved, but false positives from charge sharing events increase
Solution Approach 1:
An intermediary processing stage is introduced between charge detection and energy discrimination. This intermediate stage analyzes the spatial distribution of charge across pixels and identifies charge-sharing events before they contaminate the energy spectrum. By filtering out false events at this intermediate stage, the system maintains accurate energy resolution while reducing false positives in material delineation.
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 effectively corrects for charge-sharing events, enhancing the accuracy of X-ray detection and enabling sub-pixel spatial resolution, thereby improving the quality of X-ray imaging and energy discrimination in radiation detectors.
Implementation Method 1
a detector may employ direct-conversion of incident X-rays to electrical signals, such as a detector based on silicon strips or other semiconductor materials (such as cadmium zinc telluride (CZT) or cadmium telluride (CdTe)) that generate a measurable signal when the semiconductor substrate is itself exposed to X-ray photons
Data Source
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AI summary
The present approach relates to the use of reference pixels provided between the primary pixels of a detector panel. Coincidence circuitry or logic may be employed so that the measured signal arising from the same X-ray event may be properly, that is the signal measured at both a reference and primary pixel may be combined so as to provide an accurate estimate of the measured signal, at an appropriate location on the detector panel.