C-Arm Fluoroscope Pose Refinement for Wigwag Compensation
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Solution Overview
Problem
Fluoroscopic imaging struggles to resolve small soft-tissue objects like lesions due to their low density, and 2D projections lack the accuracy needed for precise navigation within the body, necessitating a fast and accurate 3D reconstruction during medical procedures.
Innovation Solution
A method is employed to compensate for secondary movement in C-arm fluoroscopes by detecting markers, estimating primary and secondary movement axes, and refining camera poses using a Graham-Schmidt algorithm to achieve 3D position estimation, incorporating a 2D grid pattern and radiopaque beads for marker detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If fluoroscopic imaging is used to visualize structures during medical procedures, then real-time navigation capability is improved, but measurement precision deteriorates due to difficulty resolving small soft-tissue objects and 2D projection limitations
Solution Approach 1:
The patent transforms 2D fluoroscopic images into 3D reconstructed structures by performing a fluoroscopic sweep and reconstructing volumetric data. This dimensionality change enables precise localization of small soft-tissue objects while maintaining real-time navigation capability during medical procedures.
2Area of stationary object
If C-arm fluoroscope is moved during fluoroscopic sweep, then 3D reconstruction coverage is improved, but measurement precision deteriorates due to secondary movement (wigwag) causing misalignment
Solution Approach 1:
The system uses detected markers to estimate primary and secondary movement axes, then applies compensation transformations to correct for wigwag movement. This feedback mechanism maintains alignment accuracy across the full 3D reconstruction coverage area by continuously adjusting for C-arm movement deviations.
Solution Approach 2:
The patent estimates translation and rotation parameters of the C-arm during the fluoroscopic sweep, then applies compensation transformations based on these estimated parameters. This allows the system to maintain measurement precision while achieving comprehensive 3D coverage through dynamic parameter adjustment.
3Measurement precision
If markers are detected in fluoroscopic images to enable 3D reconstruction, then measurement precision is improved, but device complexity increases due to multiple processing steps
Solution Approach 1:
The patent introduces detected markers as intermediary reference points between the C-arm fluoroscope and the 3D reconstruction process. These markers serve as mediators that enable accurate 3D position estimation through a systematic processing pipeline involving marker detection, movement axis estimation, and pose refinement.
Data Source
AI summary
Imaging systems and methods compensate for wigwag movement of a C-arm fluoroscope to refine camera pose estimates. The methods involve computing a primary movement axis from samples of markers in fluoroscopic images of a fluoroscopic sweep of a structure of markers and processing the primary movement axis to obtain a secondary movement axis. The methods further involve aligning two-dimensional samples of each marker with the primary and secondary movement axes to obtain an aligned signal and determining a difference signal for a secondary component of the aligned signal. The difference signal is then converted to a rotation axis translation signal. The method further involves estimating a 3D position of the rotation axis. The estimated pose of the C-arm fluoroscope is then refined to compensate for the wigwag movement using the rotation axis translation signal and the estimated 3D position of the rotation axis.