Photon Counting Detector Offset Correction via Artificial Signal Pulses
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Solution Overview
Problem
Photon counting detectors face reduced quality of detection values due to offsets caused by persistent currents, which corrupt the distribution of signal pulses among energy bins.
Innovation Solution
A detection apparatus that generates artificial signal pulses with a predefined height and rate, allowing the detection values generation unit to determine an offset by comparing these pulses with a threshold, thereby correcting the distribution of detection signal pulses among energy bins and improving detection value quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If artificial signal pulses with predefined height and rate are generated and compared with a threshold, then the offset of detection signal pulses can be reliably determined, but the device complexity increases due to the additional signal pulse generation unit and threshold comparison mechanism
Solution Approach 1:
The patent introduces artificial signal pulses as an intermediary element to indirectly measure the offset. Instead of directly measuring the offset of detection signal pulses, the system generates artificial pulses with known characteristics, compares them with a threshold, and determines the offset from the observed rate of threshold crossings. This intermediary approach enables reliable offset determination while keeping the implementation feasible.
Solution Approach 2:
The system creates artificial copies of signal pulses with predefined characteristics (height and rate) that mimic the structure of real detection pulses but have known parameters. By analyzing the behavior of these artificial pulse copies against the threshold, the system can infer the offset without directly measuring the detection pulses themselves, thus enabling precise offset determination.
2Reliability
If the artificial signal height threshold is set similar to or larger than the predefined artificial signal pulse height, then the observed rate becomes a reliable measure for offset determination, but the measurement precision is reduced when the threshold is set too high
Solution Approach 1:
The patent systematically varies the threshold parameter to find the optimal setting for offset determination. By analyzing how the observed rate changes with different threshold values (similar to or larger than the predefined pulse height), the system can reliably determine the offset while maintaining measurement precision through careful parameter selection and calibration.
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 solution reliably determines and corrects for offsets in detection signal pulses, enhancing the accuracy and quality of energy-resolved detection values, leading to improved imaging and detection capabilities.
Implementation Method 1
a direct conversion material is used for transforming photons into signal pulses, wherein each signal pulse corresponds to a single photon and wherein the signal pulse height of the respective signal pulse is indicative of the energy of the respective photon
Data Source
AI summary
A detection apparatus for detecting photons, such as used in radiographic imaging systems includes a detection unit that generates detection signal pulses having a detection signal pulse height being indicative of the energy of the detected photons, a detection values generation unit that generates energy-resolved detection values depending on the detection signal pulses and a signal pulse generation unit that generates artificial signal pulses having a predefined artificial signal pulse height and a predefined generated rate. The detection values generation unit determines an observed rate of the artificial signal pulses having an artificial signal pulse height being larger than a predefined threshold as observed by the detection values generation unit and determines an offset of the detection signal pulses depending on the determined observed rate. This allows reliably determining the offset of the detection signal pulses, which can be used for correcting the finally generated detection values.