X-ray Imaging Sensor Calibration via Light Source Intermediary
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Solution Overview
Problem
Existing X-ray imaging systems face challenges in easily performing calibration due to the need for controlled X-ray irradiation and variations in sensor element characteristics, particularly in active pixel sensors with high nonlinearity and gain variations.
Innovation Solution
An imaging system that applies input voltage to amplification transistors at predetermined intervals, acquires corresponding outputs, and derives calibration characteristics based on input-output relationships, allowing for calibration without prior X-ray imaging and accounting for individual pixel variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If X-ray irradiation is performed in advance to obtain density values for calibration, then calibration accuracy is improved, but operational complexity and difficulty increase due to strict control requirements
Solution Approach 1:
The patent introduces a light source as an intermediary to replace X-ray irradiation for obtaining reference values. Instead of using X-rays to illuminate the reference plate, visible light is used, which can be easily generated and controlled without special safety precautions. This mediator allows the calibration process to proceed with ordinary equipment while maintaining the ability to obtain accurate reference density values for calibration.
2Measurement precision
If reading is performed in advance to obtain correction values, then calibration is achieved, but time is lost due to preliminary preparation requirements
Solution Approach 1:
The patent applies preliminary action by pre-storing reference images of the reference plate in memory before actual calibration is needed. These reference images are captured once and saved, allowing rapid calibration without repeated preliminary preparations. When calibration is required, the system simply retrieves the stored reference images and compares them with current images, significantly reducing the time loss associated with advance reading and preparation.
3Measurement precision
If density reference plates with known density values are photoelectrically scanned, then calibration data is obtained, but device complexity increases due to specialized equipment requirements
Solution Approach 1:
The patent replaces the complex X-ray imaging system with a simpler visible light imaging system for obtaining reference values. Instead of using an X-ray source and X-ray detector, the system uses a conventional light source and standard image sensor. This substitution maintains the functional capability to obtain density information while dramatically reducing device complexity and eliminating the need for specialized radiation equipment.
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
Enables easy and accurate calibration of X-ray images by deriving calibration characteristics without pre-imaging preparations, effectively addressing variations in sensor elements and improving signal quality.
Implementation Method 1
an indirect conversion type sensor element in which X-rays are converted into light by a scintillator and then converted into the electrical signal by a photoelectric conversion element
Data Source
AI summary
An imaging system includes an input voltage setting unit that applies an input voltage to an Amp transistor, a setting output value acquisition unit that acquires a corresponding output for each pixel, and a calibration characteristic deriving unit that derives an input-output characteristic indicating a correspondence relationship between the input voltage and the output and derives a calibration characteristic to be used for calibration based on an inverse characteristic of the input-output characteristic.