Photon-Counting Detector Multiplexing for ADC Bottlenecks
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Solution Overview
Problem
Conventional analog-to-digital converters (ADCs) in CT systems limit performance and resolution due to high conversion time, with high-speed ADCs being expensive, creating a bottleneck in system performance and cost.
Innovation Solution
A photon-counting apparatus with multiple detectors and ADC circuits, where an intelligent multiplexer dynamically adjusts interconnections based on photon-counting rates, interleaving signals among ADC circuits, and switching to integration mode at high rates to maintain high sampling rates and resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional ADCs are used to digitize photon-counting signals, then system cost is reduced, but sampling rate and resolution are limited due to high conversion time
Solution Approach 1:
The system segments the photon-counting detectors into multiple groups and assigns each group to a different ADC circuit. The intelligent multiplexer dynamically routes signals from different detector groups to different ADCs, enabling parallel processing of multiple signals simultaneously. This segmentation allows the system to achieve high effective sampling rates using multiple slower ADCs instead of requiring a single high-speed ADC.
Solution Approach 2:
The intelligent multiplexer implements periodic time-interleaved sampling by cyclically switching between different detector groups and ADC circuits based on photon-counting rates. The system alternates between counting mode and integration mode periodically, and dynamically adjusts the interleaving pattern of ADC outputs to maintain high sampling rates across varying photon flux conditions.
2Measurement precision
If high-speed ADCs are used to improve sampling rate and resolution, then system performance is improved, but system cost increases prohibitively
Solution Approach 1:
The system merges the output signals from multiple standard-speed ADC circuits through the intelligent multiplexer's time-interleaved combining mechanism. By dynamically interleaving and combining outputs from multiple ADCs based on photon-counting rates, the system achieves the effective resolution and sampling rate of a high-speed ADC while using multiple affordable standard-speed ADCs instead.
Solution Approach 2:
The intelligent multiplexer provides multi-functional operation by dynamically adjusting its interconnection pattern based on photon-counting rates. It can operate in counting mode for low rates, integration mode for high rates, and dynamically adjust ADC interleaving patterns, making a single system architecture universally applicable across varying operational conditions without requiring specialized high-speed ADCs.
3Productivity
If the number of ADC circuits is increased to improve sampling rate through parallel processing, then system complexity and cost increase
Solution Approach 1:
The intelligent multiplexer implements dynamic reconfiguration of the detector-ADC interconnection pattern based on real-time photon-counting rates. The system dynamically adjusts which detectors are connected to which ADCs and how ADC outputs are interleaved, optimizing the use of a fixed number of ADC circuits across varying operational conditions. This dynamic adaptation maximizes effective sampling rate without requiring an ever-increasing number of ADCs.
4Quantity of substance
If photon-counting rate increases, then more information is captured, but conventional ADCs cannot keep up with the signal rate
Solution Approach 1:
The system changes operational parameters dynamically based on photon-counting rates. The intelligent multiplexer switches between counting mode and integration mode depending on the photon flux level. At high photon-counting rates, the system transitions to integration mode with adjusted ADC interleaving patterns, enabling the processing of high photon fluxes that would overwhelm conventional ADCs operating in fixed counting mode.
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 enables high sampling rates and resolution in CT systems without the need for high-speed ADCs, improving system performance and reducing costs by optimizing ADC usage based on photon-counting rates.
Implementation Method 1
photon-counting detectors that are able to count individual photons that impinge on them and generate a corresponding signal
Data Source
AI summary
A photon-counting system includes photon-counting detectors that output photon-counting signals to indicate a number of photons impinging on the photon-counting detectors. The system also includes analog-to-digital conversion circuits, which convert one of the photon-counting signals into a digital photon-counting signals, and a processor that processes the digital photon-counting signals to extract information from the photon-counting signals. The information extracted can include a photon-counting rate. An intelligent multiplexer that, based on the photon-counting rate, modifies interconnection of the photon-counting detectors and analog-to-digital conversion circuits and provides digital photon-counting signals for a selected set of the analog-to-digital converters to the processor.