Multi-Camera X-Ray Detector Parallax-Free Calibration
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Solution Overview
Problem
Existing multi-camera flat panel X-Ray detectors face challenges in correcting geometric distortion without introducing parallax distortion, especially when the detector is enclosed in a casing, as direct calibration methods can lead to contamination and inaccurate correction functions due to parallax effects.
Innovation Solution
The method involves placing internal and external markers at known locations within and outside the detector casing, respectively, acquiring X-Ray images, and calculating a parallax-free transformation using polynomial coordinate mappings to correct geometric distortion, allowing for adjustment of X-Ray images during routine operation without opening the detector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the grid is placed on top of the scintillator directly for calibration, then geometric distortion correction accuracy is improved, but the detector casing must be opened which can lead to contamination
Solution Approach 1:
The patent introduces a transparent calibration grid that can be placed on the detector cover (an intermediary surface) rather than directly on the scintillator. This allows calibration to proceed through the cover material, eliminating the need to open the detector casing and thus preventing contamination while still enabling accurate geometric distortion correction
Solution Approach 2:
The calibration grid is designed to be placed on the detector cover before acquiring calibration images. This preliminary positioning allows the system to capture geometric distortion data through the cover material itself, ensuring that the correction function accounts for any refraction or distortion introduced by the cover while maintaining detector integrity
2Object-affected harmful factors
If the grid is placed on the casing of the detector at a distance from the scintillator, then contamination is avoided, but parallax distortion occurs which reduces correction accuracy
Solution Approach 1:
The detector cover serves as an intermediary medium that allows the calibration grid to be positioned on the casing (avoiding contamination) while still enabling accurate geometric distortion measurement. The calibration process accounts for the cover's optical properties, ensuring that parallax distortion is minimized or corrected for in the final geometric distortion correction function
Solution Approach 2:
The patent modifies the calibration approach by changing the parameter of grid positioning from 'directly on scintillator' to 'on detector cover'. This parameter change, combined with adjusting the calibration methodology to account for cover-induced distortion, resolves the contradiction between avoiding contamination and maintaining correction accuracy
3Measurement precision
If the distance from the X-Ray source to the detector is increased to reduce parallax distortion, then correction accuracy improves, but the system becomes less adaptable to real life settings
Solution Approach 1:
The detector cover acts as an intermediary that enables accurate geometric distortion calibration without requiring extreme source-to-detector distances. By placing the calibration grid on the cover and accounting for the cover's optical effects, the system achieves high correction accuracy while maintaining flexibility in source positioning for various clinical applications
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 minimizes the influence of parallax distortion on geometric correction, providing accurate and reliable image adjustment without compromising the detector's integrity, thereby enhancing image quality and reducing operational errors.
Implementation Method 1
a scintillator to convert X-Ray radiation into detectable radiation
Data Source
AI summary
System and method for correcting geometric distortion in a multi-camera flat panel X-Ray detector. A scintillator converts X-Ray radiation generated by an X-Ray source into detectable radiation. Internal markers are placed at known locations adjacent to the scintillator, inside a casing of the detector. External markers placed at known locations outside the casing, adjacent to a cover of the detector. At least one imaging sensor acquires, during the calibration phase, a partial image depicting the external markers and the internal markers. The location of the external markers and the internal markers on the partial X-Ray image is found. A parallax free transformation for correcting geometric distortion based on differences between relation between physical location of the external markers and location of the external markers on the X-Ray image and relation between physical location of the internal markers and location of internal markers on the partial X-Ray image is calculated.