Electromagnetic Navigation Calibration for Distortion Compensation
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Solution Overview
Problem
Electromagnetic navigation systems face accuracy issues due to distortions caused by conducting and magnetic materials within the navigation field, which can affect the precision of tracking devices during medical procedures.
Innovation Solution
The implementation of a method to determine and calibrate the electromagnetic field distortions caused by materials such as holding frames, using software algorithms and factory calibration to ensure accurate navigation, by minimizing eddy currents and ferromagnetic induced distortions, and positioning the localizer to reduce interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conducting or magnetic materials are present within the navigation field, then the electromagnetic field is distorted, but navigation accuracy deteriorates
Solution Approach 1:
The patent applies preliminary action by performing factory calibration during manufacturing to determine and store the distortion characteristics of holding frames before actual surgical procedures. The system pre-characterizes the electromagnetic distortion caused by each holding frame configuration, so that when surgery begins, the pre-measured distortion data is already available for compensation, eliminating the need for time-consuming on-site calibration and ensuring immediate navigation accuracy.
Solution Approach 2:
The system implements feedback by continuously comparing the expected electromagnetic field (without distortion) against the actual measured field (with distortion) and using this information to compensate for positioning errors. The navigation system measures the actual field conditions, compares them to the pre-stored distortion characteristics, and adjusts the calculated instrument positions to account for the distortion, creating a closed-loop correction system that maintains accuracy despite the presence of conducting or magnetic materials.
2Measurement precision
If factory calibration is performed to determine field distortion, then navigation precision is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by performing factory calibration during manufacturing to determine and store the distortion characteristics of holding frames before actual surgical procedures. The system pre-characterizes the electromagnetic distortion caused by each holding frame configuration, so that when surgery begins, the pre-measured distortion data is already available for compensation, eliminating the need for time-consuming on-site calibration and ensuring immediate navigation accuracy.
Solution Approach 2:
The system applies parameter changes by transforming the physical distortion characteristics of holding frames into stored numerical data representations. During factory calibration, the actual electromagnetic field distortion is measured and converted into mathematical parameters that describe the distortion pattern. These parameters are then stored in memory for later use, converting a complex physical measurement problem into a manageable data storage and retrieval task that simplifies the overall manufacturing and operational process.
3Object-affected harmful factors
If the localizer is repositioned to reduce interference, then field distortion is minimized, but device complexity increases
Solution Approach 1:
The system implements feedback by continuously comparing the expected electromagnetic field (without distortion) against the actual measured field (with distortion) and using this information to compensate for positioning errors. The navigation system measures the actual field conditions, compares them to the pre-stored distortion characteristics, and adjusts the calculated instrument positions to account for the distortion, creating a closed-loop correction system that maintains accuracy despite the presence of conducting or magnetic materials.
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 ensures precise navigation of instruments by accounting for and compensating for field distortions, maintaining accuracy even in the presence of distorting materials, thereby enhancing the reliability of electromagnetic navigation systems in medical procedures.
Implementation Method 1
an electromagnetic field (EM field) is generated by a localizer and sensed by a tracking device
Implementation Method 2
The EM field generated by a localizer can be affected by various materials, such as conducting or magnetic materials, within the volume where navigation is to occur
Implementation Method 3
Cuts or breaks in structures can minimize eddy current loops to minimize distortion
Implementation Method 4
Also, the shape, geometry, and magnetic features of materials can effect distortion
Data Source
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AI summary
Disclosed is a method and system for navigating an instrument relative to a configurable theater system. The configurable theater instrument can be any instrument positioned in a theater that is configured to have more than one position. A localizer can generate an electromagnetic field that is sensed by a tracking device to determine a location of the tracking device with the sensed electromagnetic field.