Radiation Detector Calibration via Voltage Injection
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Solution Overview
Problem
Current calibration techniques for radiography imaging systems, such as CT scanners, are time-consuming and require multiple radiation exposures, necessitating safety restrictions and technician monitoring, limiting system availability and efficiency.
Innovation Solution
A method involving the application of different voltages to a photoconductor in a direct conversion detector array to produce electrical charges, which are used for calibration, eliminating the need for radiation exposure and allowing for on-site, automated calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional radiation-based calibration is performed, then detector array calibration accuracy is improved, but calibration time increases significantly and system availability decreases
Solution Approach 1:
The patent introduces a charge injection circuit as an intermediary device that simulates radiation-induced charge generation in the photoconductor. Instead of using actual radiation, the circuit injects known charge amounts directly into the detector array, serving as a mediator between the calibration system and the detector. This allows calibration to proceed without radiation while maintaining accuracy, resolving the contradiction between calibration precision and time consumption.
Solution Approach 2:
The patent replaces the physical radiation-based calibration mechanism with an electrical charge injection mechanism. The charge injection circuit uses voltage sources and capacitors to generate and inject electrical charges into the detector array, substituting the complex radiation emission and detection process with a simpler electrical system. This substitution dramatically reduces calibration time while maintaining the ability to accurately characterize detector response.
2Measurement precision
If traditional radiation-based calibration is performed, then detector array calibration is achieved, but safety restrictions and technician monitoring are required
Solution Approach 1:
The patent converts the harmful radiation-based calibration process into a beneficial radiation-free electrical charge injection process. By recognizing that the essential function of calibration is to measure detector response to charge input, the invention replaces the harmful radiation component with a safe electrical equivalent. This eliminates radiation safety risks while preserving the calibration function, allowing unattended automated operation.
3Measurement precision
If multiple radiation exposures are used for calibration, then photon noise impact is reduced, but calibration duration extends to two hours or more
Solution Approach 1:
The patent performs preliminary charge injection actions through the charge injection circuit to characterize detector response without requiring multiple repeated radiation exposures. The circuit can rapidly inject known charge amounts and measure detector response multiple times in succession, accumulating statistical data quickly. This preliminary characterization approach reduces the need for lengthy multi-hour calibration sessions while achieving equivalent noise reduction through repeated rapid measurements.
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 reduces calibration time significantly, eliminates the need for radiation safety measures, and enables more efficient system operation by allowing calibration during off-peak hours, improving image quality without the limitations of traditional methods.
Implementation Method 1
a first power source to apply a first voltage to a photoconductor of the direct conversion detector array and using a second power source to apply a second voltage to the photoconductor
Data Source
AI summary
Among other things, one or more systems and/or techniques for calibrating a direct conversion detector array are provided. An electrical charge is generated on an interface of a photoconductor (e.g., amorphous selenium) of the detector array when there is a change in voltage that is applied to the photoconductor. Such a change in voltage may occur because the voltage that is supplied to the photoconductor by a power supply is changed. The changed voltage causes an electrical charge to be produced, or causes a change in the net charge density at an interface of the photoconductor, that is substantially similar to the electrical charge that may be produced when radiation impinges the detector array. In this way, calibrations of the detector array (e.g., the generation of a uniformity map, defect table, etc.) may be performed without the emission of radiation and onsite or outside of a factory setting.