X-ray Detector Charge Sharing Management
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Solution Overview
Problem
Charge sharing in semiconductor X-ray detectors leads to inaccurate measurement of X-ray photon energy, as the energy is determined by the amount of electric charges generated, and this is particularly problematic in applications like elemental analysis where precise photon energy measurement is required.
Innovation Solution
The system manages charge sharing by using a controller to determine the energy of an X-ray photon based on voltages from multiple pixels, where the controller calculates the sum of absolute voltages from neighboring pixels and assigns the photon to one pixel for image formation based on voltage comparison and relative positions, effectively addressing the issue of charge sharing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If charge carriers generated by a single X-ray photon are collected by multiple pixels, then the detector can capture the full charge signal, but the measurement precision of X-ray photon energy deteriorates due to charge sharing
Solution Approach 1:
The patent segments the charge signal collection by assigning each detected charge event to a specific pixel based on voltage comparison. When charge sharing occurs between adjacent pixels, the controller compares voltages and assigns the photon to the pixel with the higher voltage, ensuring each photon is counted once and its energy is measured by a single pixel, thus resolving the charge sharing problem while maintaining full charge signal capture.
2Measurement precision
If the controller assigns photons to pixels based on voltage comparison, then measurement precision is improved, but the device complexity increases due to additional control logic
Solution Approach 1:
The patent implements a self-service mechanism where each pixel independently compares its voltage with its neighbor's voltage and autonomously determines whether to claim the photon event. This distributed decision-making approach reduces the burden on the central controller and simplifies the overall system architecture while maintaining accurate photon assignment based on voltage comparisons.
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 measurement of X-ray photon energy even in cases of charge sharing, improving the precision of X-ray detection and image formation in various applications, including radiography, cargo scanning, and elemental analysis.
Implementation Method 1
When an X-ray photon is absorbed in the semiconductor layer, multiple charge carriers (e.g., electrons and holes) are generated
Implementation Method 2
each pixel may include a capacitor that is charged with a voltage proportional to an amount of charge carriers collected by the pixel
Data Source
AI summary
An apparatus suitable for detecting X-ray is disclosed. In one example, the apparatus comprises an X-ray absorption layer comprising a first pixel and a second pixel, and a controller. The controller is configured for determining that carriers generated by a single X-ray photon are collected by the first pixel and the second pixel. The controller is also configured for determining energy of the single X-ray photon based on a first voltage detected from the first pixel and a second voltage detected from the second pixel. The first voltage and the second voltage are caused by the single X-ray photon.