Medical Calibration Method for Marker Pose Deviation Compensation
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Solution Overview
Problem
The accuracy of medical calibration for medical instruments is limited by the accuracy of marker pose determination and tolerances in marker attachment, leading to incorrect medical navigation, especially with large working distances between markers and imaging sensors.
Innovation Solution
A method that captures image representations of medical markers and instruments, determines their spatial pose, and adjusts the spatial pose relationship between markers and tracking points to minimize deviations, optimizing the determination of tracking point positions and compensating for manufacturing and attachment tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a marker is fastened to a medical instrument for calibration, then the spatial position of the instrument can be determined, but manufacturing and attachment tolerances cause deviations between the determined position and the actual position
Solution Approach 1:
The patent applies parameter changes by optimizing the spatial pose relationship parameters between the marker and tracking point. Instead of relying solely on fixed manufacturing tolerances, the system adjusts and refines the transformation parameters through calibration procedures, allowing the mathematical model to compensate for physical attachment variations. This transforms a manufacturing precision problem into a parameter optimization problem.
Solution Approach 2:
The patent implements feedback by using image data to continuously monitor and adjust the determined position of the tracking point. The system captures images, determines marker pose, calculates tracking point position, and uses this information to refine the spatial relationship model. This closed-loop feedback mechanism allows real-time compensation for attachment tolerances and improves measurement accuracy despite manufacturing variations.
2Length of stationary object
If the working distance between marker and imaging sensor is increased, then the measurement range is expanded, but the accuracy of navigation deteriorates
Solution Approach 1:
The patent addresses this contradiction by creating an asymmetric calibration approach where the spatial pose relationship is determined through optimized mathematical modeling rather than symmetric geometric assumptions. The system uses asymmetric optimization techniques to refine the transformation parameters, allowing accurate navigation even when the working distance varies, thus decoupling accuracy from fixed geometric constraints.
3Ease of manufacture
If conventional calibration methods are used with fixed marker-instrument relationships, then the calibration process is simple, but the accuracy deteriorates due to tolerances in manufacturing and attachment
Solution Approach 1:
The patent applies preliminary action by performing a calibration procedure that establishes an optimized spatial pose relationship before actual use. This preliminary calibration step creates a refined transformation model that compensates for manufacturing and attachment tolerances. By doing the optimization work in advance, the system maintains both ease of use during actual operation and high accuracy through the pre-determined optimal parameters.
Data Source
AI summary
The present disclosure relates to a method of medical calibration, including the method steps of: capturing an image representation of a medical marker and of a medical instrument connected therewith; determining a spatial pose of the medical marker on the basis of the image representation; determining a first position of a tracking point of the medical instrument on the basis of the determined spatial pose and on the basis of information relating to a spatial pose relationship between medical marker and tracking point, and determining a second position of the tracking point on the basis of the captured image representation; determining a deviation between the first position and the second position; adjusting the information relating to the spatial pose relationship between medical marker and tracking point on the basis of the determined deviation.