X-ray Detector Sensor Polarization Calibration
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Solution Overview
Problem
X-ray detectors experience signal drift due to polarization effects in semiconductor materials, leading to inaccuracies in medical imaging, particularly in computed tomography scans, as the polarization state changes over time and varies between examinations, affecting the charge carrier mobility and signal intensity.
Innovation Solution
A method is developed to determine the polarization state of an X-ray detector's sensor by illuminating it with a sequence of light pulses of varying intensity, allowing the determination of charge pulses exceeding a threshold voltage, thereby establishing a relationship between illumination intensity and polarization state without the need for X-ray irradiation, and using this information to correct signal drift and calibrate the detector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If X-ray detectors are used for medical imaging, then diagnostic capability is improved, but signal drift occurs due to polarization effects causing measurement inaccuracies
Solution Approach 1:
The patent applies preliminary action by illuminating the semiconductor sensor with light pulses before actual X-ray measurement to determine the polarization state in advance. This allows the system to know the current polarization state and apply appropriate corrections during X-ray detection, thereby maintaining measurement accuracy despite polarization-induced signal drift.
Solution Approach 2:
The patent implements feedback by continuously monitoring the polarization state through light pulse illumination and using this information to correct X-ray measurement signals. The system measures the polarization state, compares it against reference values, and applies corrections to maintain accurate X-ray detection, creating a closed-loop control system that compensates for polarization effects.
2Measurement precision
If polarization state is determined using light pulses, then signal drift correction is improved, but additional illumination requirements increase device complexity
Solution Approach 1:
The patent applies universality by designing the illumination unit to serve dual functions: it provides light pulses for determining polarization state and also serves as part of the detector assembly for X-ray measurements. This multi-functional approach allows polarization monitoring without adding separate dedicated illumination equipment, thereby reducing overall device complexity.
Solution Approach 2:
The patent implements self-service by using the detector's own illumination unit to determine its polarization state. The system uses internally available light sources and optical components to perform self-diagnosis and self-correction of polarization effects, eliminating the need for external calibration equipment or additional measurement devices.
3Productivity
If charge carrier mobility is maintained, then detector efficiency is improved, but polarization effects cause mobility reduction over time
Solution Approach 1:
The patent applies mechanics substitution by replacing direct electrical measurement of charge carrier properties with optical measurement using light pulses. Instead of measuring charge carrier mobility directly through electrical means, the system uses optical illumination to determine polarization state, which then informs corrections for charge carrier behavior, avoiding direct interference with the charge carriers.
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 method enables accurate determination of the polarization state and signal drift without additional X-ray radiation, improving the stability and efficiency of X-ray detectors by reducing signal drift and enhancing the signal-to-noise ratio, while also allowing for precise calibration and testing of the detector's functionality.
Implementation Method 1
a sensor unit (2, 3, 4) which is configured to generate a sensor signal (s1, s2, s3, S) according to a detected X-ray pulse (P)
Data Source
AI summary
A method is described for determining the polarization state of a sensor of an X-ray detector. In the method, the X-ray detector is illuminated with a sequence of light pulses wherein the individual pulses of the light pulse sequence have a different intensity. It is further determined at what intensity of the light pulses, charge pulses generated by the sensor of the X-ray detector exceed a threshold voltage of a signal detection circuit. Also described is a method for obtaining and/or setting functional data of a sensor of an X-ray detector and/or of a sensor illumination unit. Furthermore, an X-ray detector is described.