Optical Shape-Sensing Registration for Connector Misalignment
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Solution Overview
Problem
Existing optical shape sensing systems face inaccuracies in determining the position and orientation of medical devices due to manufacturing tolerances and misalignments in connectors, particularly in back loadable guide wires, affecting the accuracy of surgical procedures.
Innovation Solution
A method is developed to register an optical shape sensing system by positioning the optical connector in multiple orientations and measuring the shape and orientation of both distal and proximal fibers, allowing for the determination of separate transformations in the launch base and connector, thereby compensating for misalignments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a robust connector key is used to ensure alignment in back loadable guide wires, then alignment precision is improved, but manufacturing difficulty increases due to the small outer diameter constraints
Solution Approach 1:
The connector alignment problem is segmented into multiple measurable components by introducing separate transformation matrices for the launch base (TL) and connector (TC). Instead of treating alignment as a single monolithic parameter, the system divides it into transformable elements that can be independently calibrated and compensated, allowing precise alignment without requiring overly complex connector keys.
Solution Approach 2:
The patent changes the parameters of the registration process by using multiple transformation matrices (TL for launch base, TC for connector, TGWT for guide wire) that can be independently adjusted and compensated. This parameter-based approach allows the system to achieve precise alignment through mathematical compensation rather than relying solely on mechanical precision in the connector key.
2Ease of manufacture
If manufacturing tolerances and connector misalignments are present, then ease of manufacture is improved, but measurement precision of device position and orientation deteriorates
Solution Approach 1:
The patent implements feedback through the registration process where the measured shape of the guide wire (GWshape) is compared with the expected shape, and the transformation matrices (TL, TC) are adjusted accordingly. This feedback mechanism allows the system to compensate for manufacturing tolerances and connector misalignments by continuously refining the transformation parameters based on actual measurements.
Solution Approach 2:
The patent performs preliminary registration actions by establishing the transformation matrices TL and TC before the actual surgical procedure. These preliminary transformations are calculated based on the known geometric relationship between the launch base, connector, and guide wire, allowing the system to pre-compensate for expected misalignments and tolerances.
3Measurement precision
If separate transformations for launch base and connector are determined, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The transformation calculation complexity is segmented into manageable parts by introducing separate transformation matrices for the launch base (TL), connector (TC), and guide wire (TGWT). Each matrix represents a specific component's transformation, making the overall complex registration problem into smaller, more manageable sub-problems that can be solved independently and then combined.
Solution Approach 2:
The patent adds a mathematical dimension to the physical alignment problem by using transformation matrices that operate in a higher-dimensional parameter space. Instead of physically eliminating misalignments through complex mechanical means, the system resolves them through mathematical transformations in a different dimension, allowing precise position and orientation determination despite physical imperfections.
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 method enables accurate registration and tracking of medical devices despite connector misalignments, ensuring precise localization of the device tip during surgical maneuvers without requiring additional imaging.
Implementation Method 1
The optical fiber that is being used to determine the shape of the device (FORS sensor) typically comprises multiple optical cores
Implementation Method 2
In FORS, geometrical changes of the device are encoded into the light field that propagates through the optical fiber integrated in the device
Implementation Method 3
Optical interrogation of this optical fiber gives the information needed to, in principle, reconstruct the three-dimensional shape of the whole optical fiber
Data Source
AI summary
A method of registering part of an optical shape sensing system (10) to an imaging system (48) is described, said part comprising a distal multicore optical fiber (16) and a proximal multicore optical fiber (14), an optical connector (34) optically connecting the distal optical fiber (16) and the proximal optical fiber (14) to each other, a launch base (36) fixed with respect to the imaging system (48) and arranged to fix the proximal optical fiber (14). In the method, the shape and orientation of the distal optical fiber (16) and of a section of the proximal fiber (14) extending from the optical connector (34) to the launch base (36) are optically measured for at least two different positions and/or orientations of the optical connector (34) with respect to the object (28). Inter alia based on the optical measurements in the first and second positions or and/orientations of the optical connector (34), said part of the optical shape system as a whole is registered to the imaging system (48). A system for carrying out the method is also described.