EMT Position Review With C-Arm Interference Correction
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Solution Overview
Problem
Electromagnetic tracking systems for medical navigation are compromised by interference from X-ray devices, particularly when the C-arm and field generator come close, leading to inaccurate position determination and potential system failure.
Innovation Solution
A method involving registration of the EMT system with the X-ray device, use of presegmented 3D reference images, and application of plausibility criteria to correct erroneous positions, utilizing calibration factors and alternative position determinations to ensure accurate navigation without manual intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the C-arm is moved completely out of the examination area or calibrated different fixed C-arm field generator constellations to prevent interference, then the accuracy of electromagnetic tracking is improved, but the procedure time and labor are significantly increased
Solution Approach 1:
The system performs preliminary actions by automatically detecting the C-arm position before electromagnetic tracking begins, and pre-calculating correction values based on the detected position. This allows the tracking system to compensate for C-arm interference without requiring manual repositioning or recalibration, thereby maintaining accuracy while avoiding time-consuming procedural adjustments
Solution Approach 2:
The invention introduces an intermediary correction mechanism that calculates and applies position correction values based on the detected C-arm position. This intermediary correction layer allows the system to maintain accurate tracking despite the presence of the C-arm, eliminating the need to move the C-arm out of the examination area or perform time-consuming recalibrations
2Measurement precision
If manual review and correction of position determinations is performed, then the accuracy is improved, but the operator workload and procedural interruptions are increased
Solution Approach 1:
The system performs self-service by automatically detecting C-arm position and calculating correction values without requiring operator intervention. The evaluation unit autonomously compares detected positions with stored reference positions, automatically determines when correction is needed, and applies corrections without manual review, thereby reducing operator workload while maintaining high accuracy
Solution Approach 2:
The system implements continuous feedback by detecting the C-arm position, comparing it with reference data, and automatically adjusting position determinations when deviations are detected. This closed-loop feedback mechanism ensures accurate tracking while eliminating the need for manual operator review and intervention
3Productivity
If the C-arm is positioned close to the field generator to maintain acquisition capability, then the X-ray acquisition is improved, but inhomogeneities occur in the magnetic field reducing EMT system accuracy
Solution Approach 1:
The system changes the parameter of position determination by calculating correction values based on the detected C-arm position and using these corrections to adjust the EMT position measurements. This allows the system to maintain both close C-arm positioning for acquisition capability and high measurement precision by compensating for magnetic field inhomogeneities through parameter-based correction
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
Enables rapid and accurate correction of erroneous positions, reducing procedural interruptions and health risks by minimizing radiation exposure and improving navigation accuracy in medical interventions.
Implementation Method 1
An EMT system includes at least one sensor arranged on an instrument, a field generator, and an associated control and evaluation unit. Electromagnetically tracked instruments are co-visualized in a volume image
Implementation Method 2
use is made of radiation-free navigation methods... in the presence of an X-ray device with a movable acquisition system
Data Source
AI summary
A method for automatic position determination review during position tracking of an object inserted in a hollow organ of a patient by an electromagnetic tracking (EMT) system in the presence of an X-ray device with a movable acquisition system includes providing a registration of the EMT system to the acquisition system. A reference image of the hollow organ of the patient is provided, a registration of the reference image is provided to the acquisition system, a position of the object is determined by the EMT system, and an associated position on the reference image is determined. A plausibility criterion and/or a boundary condition is applied for reviewing a plausibility of the position determined by the EMT system based on the reference image. If the plausibility criterion and/or the boundary condition is violated, a position correction of the position determined by the EMT system and/or an alternative position determination is performed.