Coincidence Counting Bin for X-ray Photon Counting Detectors
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Solution Overview
Problem
Photon counting detectors (PCDs) face challenges with charge sharing and pulse pileup at high flux rates, leading to reduced spectral performance and increased effective dead time, which compromises their ability to accurately count X-ray photons.
Innovation Solution
A coincidence counting bin (CCB) system is introduced to compensate for charge sharing by counting coincident events between neighboring pixels, which helps in identifying and correcting double counts without modifying existing signal processing pathways, thus maintaining count rate capability and reducing pileup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pixel size is reduced to increase characteristic count rate per unit area, then count rate capability is improved, but charge sharing prevalence increases
Solution Approach 1:
The patent introduces an intermediary coincidence logic module that mediates between the pixel array and readout electronics. This module detects coincident signals from adjacent pixels and identifies charge sharing events without requiring physical modification of the pixel structure, thus maintaining high count rate capability while compensating for charge sharing effects
Solution Approach 2:
The system implements feedback by using coincidence logic to detect charge sharing events and feeding this information back to correct the counted photons. The coincidence output signals are used to identify and compensate for charge sharing, allowing the system to maintain spectral performance at high flux rates
2Reliability
If charge summing circuitry is implemented to compensate charge sharing, then charge sharing compensation is improved, but effective dead time increases
Solution Approach 1:
The patent replaces the mechanical/analog charge summing circuitry with a digital coincidence logic system. Instead of using analog circuits to sum charges from adjacent pixels, the system uses digital logic to detect coincident events, thereby avoiding the increased dead time associated with analog charge summing while still achieving charge sharing compensation
3Reliability
If digital count summing is used to compensate charge sharing, then charge sharing compensation is improved, but count rate capability is reduced
Solution Approach 1:
The patent applies local quality by implementing coincidence logic only at the boundaries between pixels where charge sharing is most likely to occur. Instead of applying charge sharing compensation globally across all pixels, the system locally identifies and corrects charge sharing events at pixel interfaces, minimizing the impact on overall count rate capability
4Reliability
If larger pixel sizes are used to reduce charge sharing, then charge sharing is reduced, but spectral performance is compromised
Solution Approach 1:
The patent introduces an intermediary coincidence logic module that mediates between the pixel array and readout electronics. This module detects coincident signals from adjacent pixels and identifies charge sharing events without requiring physical modification of the pixel structure, thus maintaining high count rate capability while compensating for charge sharing effects
Solution Approach 2:
The system implements feedback by using coincidence logic to detect charge sharing events and feeding this information back to correct the counted photons. The coincidence output signals are used to identify and compensate for charge sharing, allowing the system to maintain spectral performance at high flux rates
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
The CCB system improves dose efficiency by 50-80% for spectral tasks and enhances iodine and water basis material decomposition, while maintaining high flux performance without increasing pileup or reducing count rate capability.
Implementation Method 1
The coincidence logic is configured to generate a coincidence output when the comparator output data for a first pixel is received within a predetermined time interval of the comparator output data for a second pixel
Implementation Method 2
PCDs operate by comparing a signal to multiple fixed thresholds via comparators. This allows them to classify the energy of each photon arriving at the detector
Implementation Method 3
Energy discriminating, photon counting detectors (PCDs) for CT applications have undergone rapid development in recent years. PCDs estimate the energies of individual photons arriving at the detector
Data Source
AI summary
A system for charge sharing compensation for a photon counting detector. A plurality of comparators, each configured to generate comparator output data based on a threshold value, a plurality of energy bins, each of the plurality of energy bins coupled to one of the plurality of comparators, and a coincidence logic coupled to two or more of the plurality of comparators and configured to receive comparator output data associated with two or more of a plurality of pixels. The comparator output data for each pixel indicates when a signal associated with the pixel crosses a threshold value. The coincidence logic is configured to generate a coincidence output when the comparator output data for a first pixel is received within a predetermined time interval of the comparator output data for a second pixel. The system includes a coincidence counting bin coupled to the coincidence logic and configured to receive the coincidence output and generate count data based on the coincidence output.