Probe Tracking Using Mechanical Model Constraints
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Solution Overview
Problem
Current medical position sensing systems for objects within the body lack accuracy and reliability, particularly in real-time applications, as they often rely on incomplete or inaccurate measurements of spatial coordinates without considering the mechanical properties of the probe.
Innovation Solution
A method and apparatus that utilize a hybrid position sensing system combining electromagnetic and active current location tracking, with a mechanical model of the probe to minimize cost functions and generate corrected coordinates, enhancing accuracy by calibrating and adjusting measurements based on shape assumptions and differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrical impedance methods are used to detect catheter position, then the system can obtain position information, but the measurement accuracy is insufficient due to not considering probe mechanical properties
Solution Approach 1:
The system combines electrical impedance measurement data with mechanical model data to create a composite position estimation approach. The processor integrates both electrical field interactions and mechanical property constraints to determine probe position, achieving higher accuracy than either method alone.
Solution Approach 2:
The system changes the parameters used for position determination by incorporating mechanical properties (stiffness, flexibility, curvature) as additional constraints alongside electrical impedance measurements. This multi-parameter approach refines position accuracy by considering both electrical and mechanical aspects of probe behavior.
2Ease of operation
If real-time three-dimensional imaging is used to visualize the object, then visualization is achieved, but the system complexity and cost increase significantly
Solution Approach 1:
The system replaces complex three-dimensional imaging systems with a simpler coordinate determination approach based on electrical impedance measurements enhanced by mechanical modeling. Instead of using sophisticated imaging hardware, the system calculates probe position and orientation from electrical field interactions combined with known mechanical properties.
Solution Approach 2:
The mechanical model acts as an intermediary that translates electrical impedance measurements into accurate position and orientation information. Rather than directly imaging the probe, the system uses the mechanical model as a mediator to interpret electrical measurements and derive spatial coordinates.
3Measurement precision
If correction functions are applied to catheter positions, then position accuracy improves, but the calibration process becomes more complex and time-consuming
Solution Approach 1:
The mechanical model of the probe is pre-established with known stiffness and flexibility parameters before actual measurements begin. This preliminary modeling allows the system to immediately apply mechanical constraints to measurement data without requiring time-consuming calibration procedures during operation.
Solution Approach 2:
The system uses the probe's own mechanical properties as intrinsic references for position determination. By leveraging the known mechanical characteristics of the probe itself, the system performs self-calibration without requiring external calibration equipment or procedures, reducing both time and complexity.
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 significantly improves the accuracy of probe position determination within the body by integrating mechanical models with measurement data, providing enhanced precision and reliability for real-time tracking.
Implementation Method 1
A wide range of medical procedures involve placing objects, such as sensors, tubes, catheters, dispensing devices, and implants, within the body. Real-time imaging methods are often used to assist doctors in visualizing the object and its surroundings during these procedures.
Implementation Method 2
U.S. Patent Application Publications 2006/0173251, to Govari et al., and 2007/0038078, to Osadchy describe methods for sensing the position of a probe by passing electrical currents through the body between an electrode on the probe and a plurality of locations on a surface of the body. These methods likewise use the electrical impedance of the body in sensing probe position.
Data Source
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Figure 1B
Figure 2A~2B
AI summary
A method, including: receiving an input indicative of respective apparent locations of a plurality of points disposed along a length of a probe inside a body of a subject, and applying a model of known mechanical properties of the probe to the respective apparent locations so as to minimize a first cost function with respect to shapes that can be assumed by the probe in the body. The method further includes choosing a shape responsively to the minimized first cost function and determining preliminary coordinates of the apparent locations responsively to the shape, minimizing a second cost function with respect to differences between the apparent locations and the preliminary coordinates, and generating corrected coordinates of the points along the length of the probe based on the minimized second cost function.