X-ray Gain Calibration via Dynamic and Static Reference
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Solution Overview
Problem
Flexible, open gantry X-ray systems in medical imaging face challenges with time-dependent gain variations due to mechanical vibrations and structural rigidity issues, leading to distorted image quality and artifacts, requiring frequent and time-consuming calibration procedures.
Innovation Solution
A method and device for X-ray systems that involve dynamic and static gain calibration parameters, where dynamic gain calibration parameters are obtained during movement and static gain calibration parameters are obtained at a reference coordinate, allowing for adjusted dynamic gain calibration parameters to be determined, reducing the need for frequent rotational scans and enabling faster, less time-consuming calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequent calibration scans are performed to maintain image quality in flexible X-ray systems, then measurement precision is improved, but loss of time increases due to scanner unavailability
Solution Approach 1:
The patent applies preliminary action by performing a comprehensive gain calibration initially and then using the obtained gain map for subsequent corrections without requiring frequent repeated calibration scans. The system pre-characterizes the detector response at different gantry positions and uses this pre-acquired data to correct images dynamically, reducing the need for time-consuming repeated calibrations while maintaining image quality
Solution Approach 2:
The patent uses copying by creating a gain map that represents the detector's response characteristics at various gantry positions. This gain map serves as a reference copy that can be applied to correct multiple subsequent images without requiring the physical recalibration process each time, thus maintaining measurement precision while minimizing calibration time
2Manufacturing precision
If comprehensive gain calibration is performed at multiple gantry positions, then manufacturing precision is improved, but device complexity increases due to multiple calibration requirements
Solution Approach 1:
The patent applies segmentation by dividing the calibration process into discrete gantry positions (e.g., 0°, 90°, 180°, 270°) rather than requiring continuous calibration. The detector is divided into multiple elements, and gain calibration is performed independently for each element at each position. This segmented approach simplifies the overall calibration procedure while maintaining comprehensive coverage of the detector's response characteristics
Solution Approach 2:
The patent uses parameter changes by varying the gantry position as a discrete parameter during calibration rather than requiring continuous adjustment. By selecting specific angular positions for calibration and using these discrete parameter settings to generate a comprehensive gain map, the system achieves high manufacturing precision while reducing calibration complexity through parameter discretization
3Reliability
If dynamic gain calibration is performed during assembly movement, then reliability is improved, but productivity decreases due to calibration time requirements
Solution Approach 1:
The patent applies preliminary action by performing gain calibration at discrete gantry positions before actual scanning operations. The gain map is pre-computed and stored, allowing subsequent scans to use this reference data for correction without requiring real-time calibration during scanning. This ensures image quality consistency while maintaining high scan throughput by separating calibration from scanning operations
Solution Approach 2:
The patent uses periodic action by performing comprehensive gain calibration at predetermined intervals (e.g., periodically during service operation or at scheduled maintenance intervals) rather than continuously during each scan. This periodic calibration approach maintains reliability by ensuring the gain map remains accurate while preserving productivity by allowing uninterrupted scanning operations between calibration periods
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 artifacts in reconstructed images, ensures accurate absorption coefficient determination, and allows for cost- and time-effective regular calibration, particularly beneficial for frequently used X-ray CT and CBCT systems, while maintaining image quality and reducing calibration time.
Implementation Method 1
a detector (3) arranged distantly from the source (2) to detect radiation emitted by the source (2) after traversal of an imaging region
Data Source
AI summary
An X-ray system comprises an assembly that is moveable to different scan coordinates to acquire X-ray projection images at the different scan coordinates in a dynamic mode while the assembly is moving. The assembly is also moveable to a predetermined reference coordinate to acquire an X-ray projection image at the predetermined reference coordinate in a static mode while the assembly is resting. The X-ray system also comprises a processor configured to obtain dynamic gain calibration parameters from the X-ray projection images acquired in the dynamic mode at one of the different scan coordinates; obtain a static gain calibration parameter from the X-ray projection image acquired in the static mode at the predetermined reference coordinate; and determine adjusted dynamic gain calibration parameters.