X-ray Photon Counting Detector Charge Sharing Correction
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Solution Overview
Problem
In X-ray photon counting systems, charge sharing between pixels leads to inaccuracies in X-ray intensity measurement due to the sharing of charge across pixel boundaries, which existing methods fail to fully correct without using comparators or occupying significant area, especially when pixel size is small.
Innovation Solution
An X-ray data processing apparatus that calculates an effective area ratio for each X-ray source and detection energy threshold, using this ratio to perform linear transformation and correct X-ray count values, thereby reducing the influence of charge sharing without requiring comparators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a circuit for cancelling the influence of charge share is mounted in the read-out chip, then the influence of charge share can be corrected, but the comparator occupies a considerable area and variation is caused in threshold values
Solution Approach 1:
The patent introduces an intermediary approach by performing charge share correction through software processing of read-out data rather than through hardware comparators in each pixel. The correction is achieved by calculating effective area ratios and applying linear transformation to the counted values after read-out, thus avoiding the need for additional comparator circuits in the read-out chip.
Solution Approach 2:
The patent replaces the mechanical/electrical comparator-based correction system with a computational/mathematical approach. Instead of using physical comparators to cancel charge share influence, the system uses effective area ratio calculations and linear transformation equations to correct the counted values, substituting hardware complexity with software-based mathematical processing.
2Manufacturing precision
If the pixel size is made small, then the detector resolution is improved, but it becomes difficult to handle the charge share across a plurality of pixels
Solution Approach 1:
The patent changes the parameter of effective area ratio based on the actual pixel size and charge diffusion characteristics. By calculating and applying different effective area ratios for small pixels, the system adapts the correction method to the specific pixel dimensions, making charge share handling feasible even when pixels are made small for improved resolution.
3Extent of automation
If threshold values are set for each pixel to detect X-ray intensity, then X-ray counting is enabled, but charge share causes counts to vary from original counts
Solution Approach 1:
The patent implements a feedback mechanism by calculating effective area ratios based on pixel characteristics and using these ratios to correct the counted values. The correction process continuously refines the measured counts by applying transformation equations that account for charge share effects, thereby improving measurement precision while maintaining automated counting capability.
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 X-ray count values detected by pixel array detectors under charge sharing influence, improving measurement accuracy and reducing variations across pixels, even with multi-wavelength X-rays, and enhances the separation of diffraction and fluorescent X-ray data.
Implementation Method 1
In a pixel array detector of a photon counting system, typically a monolithic sensor is used
Implementation Method 2
when a carrier diffuses in a boundary part of neighboring pixels, there occurs a phenomenon called charge share in which a charge corresponding to one photon is shared between the pixels
Data Source
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Figure 2
Figure 3A
AI summary
The X-ray data processing apparatus to estimate a true value from an X-ray count value detected by the pixel array X-ray detector of a photon counting system includes a management unit 210 to receive and manage a detection value for each detection part, an effective area ratio calculation unit 230 to calculate a ratio of a detection ability under the influence of the charge share to an original detection ability in the detection part as an effective area ratio of the detection part using data regarding the detection part and data regarding an X-ray source and a detection energy threshold value, and a correction unit 250 to correct the managed count value using the calculated effective area ratio to estimate a true value.