Reference Catheter Drift Correction Algorithm
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Solution Overview
Problem
Existing medical device navigation systems face inaccuracies due to drift and shift in electrical impedance within the body, particularly when using a single reference electrode, which cannot correct for rotational and scale errors or dislodgement of the reference catheter.
Innovation Solution
A system and method that utilize an electronic control unit to initiate an algorithm correcting for shift and drift by determining the initial and current shape and position of a reference catheter, calculating the closest fit through iterative adjustment of solution parameters, and determining minimal error parameters, thereby addressing translational, rotational, and scale errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single reference electrode is used in the navigation system, then the device complexity is reduced, but the measurement precision deteriorates due to inability to correct rotational and scale errors
Solution Approach 1:
The reference catheter is segmented into multiple electrodes (at least two electrodes) instead of using a single reference electrode. This segmentation allows the system to capture multiple position points along the catheter, enabling correction of translational, rotational, and scale errors through iterative closest point algorithms that compare initial and current catheter configurations.
Solution Approach 2:
The system transitions from single-point reference (0D) to multi-point spatial reference (1D along catheter length). By measuring positions of multiple electrodes along the reference catheter, the system adds dimensional information that enables correction of rotational and scale transformations in addition to translational drift.
2Measurement precision
If bio-impedance scaling is used to correct drift, then the measurement precision is improved for translational errors, but the device complexity increases and rotational/scale errors remain uncorrected
Solution Approach 1:
The system implements continuous feedback by repeatedly comparing current reference catheter positions with initial positions and iteratively adjusting transformation parameters. The electronic control unit performs multiple iterations of the closest point algorithm, using feedback from position measurements to refine corrections for translational, rotational, and scale errors until convergence is achieved.
3Measurement precision
If the reference catheter is kept fixed to provide stable reference, then the measurement precision is improved, but the reliability deteriorates when the catheter becomes dislodged during procedure
Solution Approach 1:
The system performs preliminary documentation of the initial reference catheter configuration and uses this as a baseline for continuous comparison. By having the initial state recorded before the procedure begins, the system can detect dislodgement events and perform re-registration by comparing current positions against the pre-established initial configuration.
Solution Approach 2:
The reference catheter configuration serves itself as the reference standard. By using the actual measured positions of the reference catheter electrodes (both initial and current) rather than relying on external fixed references, the system enables self-correction and self-validation of the navigation system's accuracy.
4Measurement precision
If iterative closest point algorithm is implemented to correct all errors, then the measurement precision is significantly improved, but the computational time increases
Solution Approach 1:
The system applies partial iteration by performing a limited number of iterative closest point algorithm cycles rather than exhaustive iterations. This approach corrects the majority of translational, rotational, and scale errors through a practical number of iterations, achieving sufficient precision without the excessive computational time that would result from continuing iterations to mathematical convergence.
Data Source
AI summary
A system and method are provided for determining one or more characteristics of a device. The system and method comprises initiating an algorithm to correct for shift and drift of a reference catheter (203), determining an initial shape and position of a portion of the reference catheter at time 0 when the algorithm is initiated (201), determining a current shape and position of the portion of the reference catheter at time t after the algorithm has been initiated (205), calculating a closest fit of the current shape and position of the portion of the reference catheter to the initial shape and position of the portion of the reference catheter by iteratively adjusting a set of solution parameters (209), and determining a minimal error solution parameter (211).