Flat Panel Detector Distortion Calibration via Virtual Phantom
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Solution Overview
Problem
X-ray inspection systems with flat panel detectors face challenges in achieving high testing accuracy due to detector surface curvature and non-constant pixel size, leading to distortion errors that are difficult and costly to correct using conventional high-precision measurement methods.
Innovation Solution
A method involving a calibration phantom with discrete geometric objects, where characteristics such as uniformity, size, shape, and arrangement are used to determine location-dependent distortion errors without requiring precise measurement of the phantom's dimensions, utilizing three-dimensional x-ray images reconstructed via computer tomography for accurate calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional high-precision measurement methods (e.g., coordinate measuring instruments) are used to measure the calibration phantom, then the dimensions of the calibration phantom can be determined accurately, but the process becomes time-consuming and costly
Solution Approach 1:
The invention uses a computer-generated virtual model (copy) of the calibration phantom with precisely known dimensions, replacing the need for physical measurement. The virtual model serves as a digital twin that provides exact dimensional data without requiring time-consuming physical measurement processes.
Solution Approach 2:
The invention replaces mechanical measurement systems (coordinate measuring instruments) with a computational approach. Instead of using physical measurement tools to determine phantom dimensions, the system uses computer-generated data and image processing algorithms to obtain dimensional information efficiently.
2Measurement precision
If conventional high-precision measurement methods are used to measure the calibration phantom, then accurate dimensions are obtained, but the costs increase significantly
Solution Approach 1:
The invention creates a digital copy of the calibration phantom with embedded precise dimensional information. This virtual model eliminates the need for expensive physical measurement processes while maintaining high dimensional accuracy, significantly reducing calibration costs.
Solution Approach 2:
The invention substitutes expensive mechanical measurement systems with computational methods. By using computer-generated models and software-based image analysis, the system achieves high measurement precision without the high costs associated with precision mechanical measurement equipment.
3Device complexity
If the flat panel detector surface is assumed to be flat, then the geometric model is simple, but distortion errors occur due to actual surface curvature and non-constant pixel size
Solution Approach 1:
The invention changes the parameters of the geometric model from simple flat-plane assumptions to a more complex model that accounts for surface curvature and variable pixel size. By incorporating these additional parameters and using non-linear optimization techniques, the system achieves higher imaging accuracy while managing model complexity through efficient computational methods.
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 allows for precise correction of distortion errors, improving measuring precision without the need for time-consuming high-precision measurements, enabling more accurate geometric imaging properties determination and enhanced system performance.
Implementation Method 1
an x-ray source (11), in particular an x-ray tube emitting an x-radiation cone (14)
Implementation Method 2
an imaging x-ray detector (12), in particular a solid-state detector or semiconductor detector
Data Source
AI summary
A method and system for determining geometric imaging properties of a flat panel detector in an x-ray inspection system are described herein. The method can include arranging a calibration phantom between an x-ray source and the flat panel detector, the calibration phantom including at least one discrete geometric object. Additionally, the method can include recording at least one x-ray image of the calibration phantom with the flat panel detector. At least one discrete geometric shape is generated in the x-ray image by imaging the at least one discrete geometric object of the calibration phantom. Further, the method can include determining a location-dependent distortion error of the flat panel detector from the at least one x-ray image on the basis of at least one characteristic of the at least one discrete geometric shape. All characteristics of the at least one discrete geometric shape used for determining the location-dependent distortion error are independent of the dimensions of the calibration phantom.