Hybrid Photon Counting Detector Charge Injection Reset Circuit
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Solution Overview
Problem
Photon counting detector cells in radiation imaging systems face saturation issues at high radiation flux rates, leading to pulse pile-up and inaccurate counting of radiation photons, which limits their application in modalities like CT systems.
Innovation Solution
An electronics arrangement for a photon counting detector array that includes an integration circuit to generate a voltage signal and a charge injection circuit to reset the integration circuit when the voltage signal exceeds a specified threshold, allowing for accurate counting of radiation photons by intermittently reducing the voltage potential across the capacitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If photon counting detector cells are used to accurately count radiation photons, then measurement precision is improved, but reliability deteriorates at high radiation flux rates due to saturation and pulse pile-up
Solution Approach 1:
The detector system dynamically switches between photon counting mode and energy integrating mode based on the radiation flux rate. When the flux rate exceeds a threshold causing saturation, the system transitions to energy integrating mode, allowing the detector to adapt its operating characteristics to maintain reliability across varying radiation conditions
Solution Approach 2:
The detector cell is designed to perform multiple functions: it can operate in photon counting mode for accurate photon enumeration at low to moderate flux rates, and switch to energy integrating mode for reliable operation at high flux rates. This multi-functionality resolves the contradiction by making the detector versatile across different operating conditions
2Reliability
If energy integrating detector cells are used to handle high radiation flux rates, then reliability is improved, but measurement precision deteriorates due to inability to provide photon number and energy information
Solution Approach 1:
The system dynamically adjusts its measurement approach based on flux rate conditions. At high flux rates where energy integrating mode ensures reliability, the system maintains the ability to switch back to photon counting mode when flux rates decrease, thereby preserving measurement precision when conditions permit
Solution Approach 2:
The system monitors the radiation flux rate and uses this feedback to determine the appropriate operating mode. This feedback mechanism ensures that the detector operates in energy integrating mode only when necessary (at high flux rates), and switches to photon counting mode when flux rates allow, thus maintaining measurement precision while ensuring reliability
3Loss of energy
If photon counting mode is used to reduce radiation dose, then loss of energy is reduced, but productivity deteriorates due to saturation at high flux rates
Solution Approach 1:
The detector dynamically adapts its operating mode based on the radiation flux rate. At low to moderate flux rates, photon counting mode is used to minimize radiation dose. At high flux rates, the system switches to energy integrating mode to maintain productivity, thus optimizing the balance between energy efficiency and measurement effectiveness across different operating conditions
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 solution enables accurate counting of radiation photons even at high flux rates, reducing noise and improving the reliability of radiation imaging systems by preventing pulse pile-up and maintaining accurate photon detection.
Implementation Method 1
a radiation detection element configured to convert radiation detected by the first detector cell into charge
Implementation Method 2
an integration circuit configured to integrate charge generated by a detector cell of the photon counting detector array to generate a voltage signal
Data Source
Figure 1
Figure 2
Figure 3a~4c
AI summary
Among other things, one or more techniques and/or systems are described for resetting an integration circuit (206) of a detector cell or an electronics arrangement (200) thereof. When a voltage signal output by the integration circuit (206) exceeds a specified threshold (e.g., indicating that a specified number of radiation photons have been detected), a charge injection circuit (208) is configured to inject charge into the integration circuit (206). The injected charge is typically opposite in polarity to stored charge that is stored by a capacitor (214) of the integration circuit (206) and is configured to counteract the stored charge. In this way, a voltage potential at the capacitor (214) decreases, causing the voltage signal output by the integration circuit (206) to decrease. Moreover, a number of resets per measurement interval may be recorded to determine an average current output by a radiation detection element of the detector cell over the measurement interval to facilitate acquiring photon integration readings.