CBCT Patient Movement Correction via Rotating Coordinate System
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Solution Overview
Problem
In cone-beam computed tomography, patient movement during X-ray projection image acquisition leads to geometric inconsistency in measurement, degrading image accuracy and requiring potential re-scans, which increases radiation dose.
Innovation Solution
A data-driven algorithm using a rotating coordinate system attached to the X-ray source and detector estimates and improves the actual imaging geometry, applying corrective geometric transformations to enhance geometric consistency and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If patient movement is prevented by tight support, then geometric consistency is improved, but patient comfort and ease of operation deteriorate
Solution Approach 1:
The patent replaces mechanical constraints (tight physical support) with a computational approach (data-driven algorithm using rotating coordinate systems and geometric transformations) to correct patient movement artifacts, thereby maintaining image quality without requiring restrictive physical support
Solution Approach 2:
The patent introduces an intermediary computational process (geometric correction algorithm) between the patient movement and the final image reconstruction, allowing movement to occur while the algorithm mediates to restore geometric consistency in the reconstructed image
2Measurement precision
If patient movement is completely prevented, then image accuracy is improved, but device complexity and invasiveness increase
Solution Approach 1:
The patent substitutes complex mechanical restraint systems with a software-based geometric correction algorithm that operates on the acquired projection data, significantly reducing device complexity while maintaining image accuracy
3Manufacturing precision
If geometric correction is applied iteratively, then image quality is improved, but computational time and energy consumption increase
Solution Approach 1:
The patent applies geometric corrections as a preliminary step before the main image reconstruction process, and uses a data-driven algorithm that leverages the intrinsic geometry of CBCT imaging to reduce the number of iterative corrections needed, thereby reducing computational energy consumption
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
The method improves image sharpness, detail, and contrast, potentially reducing the need for re-scans and minimizing radiation dose by enhancing geometric consistency in CBCT reconstructions.
Implementation Method 1
the X-ray beams diverge and form a pyramid-shaped cone
Implementation Method 2
a data-driven algorithm utilizing an intrinsic, rotating coordinate system attached to the spatial positions and orientation of the X-ray source and detector is used to establish an improved estimate of the actual imaging geometry
Data Source
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AI summary
A patient movement correction method for cone-beam computed tomography based on an iterative refinement of an initial projection geometry estimate describing the spatial positions and orientation of an X-ray source and detector during the acquisition of X-ray projection images. The acquired set of X-ray projection images are used for computing intermediate CBCT reconstructions during the corrective iteration, and projection-image-specific corrective geometric transformations are established by maximizing the similarity of the measured and reprojected X-ray projection images. The corrective geometric transformations are determined in a projection-image-specific rotating coordinate system corresponding to the spatial positions and orientations of the X-ray source and X-ray detector during the acquisition of the X-ray projection images. The final CBCT reconstruction is computed using the corrected projection geometry estimate.