Calibration Procedure for Radiology Table and C-Arm Positioning
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Solution Overview
Problem
Current calibration methods for medical imaging systems fail to accurately account for the mechanical behavior and movement of radiology examination tables relative to vascular gantries, leading to suboptimal quality in recalibrated augmented fluoroscopic images.
Innovation Solution
A calibration procedure for the mechanical model of a radiology examination table that uses a phantom target and positioning sensors to determine the table's mechanical parameters, allowing for precise determination of its movements and recalibration of 3-D and fluoroscopic images by combining image data with sensor information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a calibration method that ignores table mechanical behavior is used, then the calibration process is simple, but the quality and accuracy of recalibrated augmented fluoroscopic images deteriorates
Solution Approach 1:
The patent applies preliminary action by performing table calibration before the actual medical imaging procedure. A calibration phantom is positioned on the table and images are acquired at multiple predetermined table positions to establish mechanical parameters (play, distortion, movement characteristics) before clinical use. This preliminary calibration enables accurate compensation of table mechanical effects during subsequent augmented fluoroscopy without adding complexity to the real-time imaging process.
2Productivity
If table mechanical parameters are not determined, then the calibration procedure is simple, but the quality of augmented fluoroscopic images deteriorates
Solution Approach 1:
The patent applies partial action by focusing calibration efforts on the specific table positions and mechanical parameters most critical for augmented fluoroscopy accuracy. Rather than calibrating all possible table movements and parameters, the method selects key positions (e.g., centered position and extreme positions) and determines essential mechanical parameters (play, distortion, movement vectors) that have the greatest impact on image alignment quality. This selective approach maintains calibration efficiency while achieving sufficient image quality.
3Measurement precision
If precise table mechanical parameters are determined, then the quality of augmented fluoroscopic images improves, but the calibration complexity increases
Solution Approach 1:
The patent uses a calibration phantom as an intermediary object to indirectly determine table mechanical parameters. The phantom contains known geometric features (e.g., markers, patterns) that are imaged at multiple table positions. By analyzing the apparent position and distortion of these known features in the images, the system infers table mechanical parameters without requiring direct measurement of table movements or forces. This intermediary approach simplifies the calibration procedure while achieving precise parameter determination.
Data Source
AI summary
A method of calibrating a mechanical model of behavior and movement of an interventional radiology table by moving the table over at least one degree of freedom, acquiring at least one set of images corresponding to different positions of the table and C-arm, obtaining at least one set of images of a test object from different positions, using the images of the test object to determine parameters of the mechanical model of table behavior and movement, and combining these parameters with data given by table movement sensors so as to deduce the true relative positions of the table with respect to the medical imaging system.