Flexible Tether with Optical Shape Sensors for Medical Instrument Tracking
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Solution Overview
Problem
Current medical imaging systems face challenges in accurately localizing functional parts of instruments during intervention procedures due to limited real-time information, line-of-sight issues with marker-based tracking methods, and sensitivity to external electromagnetic fields, leading to uncertainties and increased patient risks.
Innovation Solution
A markerless tracking system using optical fibers with Fiber Bragg Gratings and Rayleigh scatterers to determine the shape and location of instruments within anatomical structures, connected via a tether to a C-arm CT imaging system, providing precise strain and curvature measurements for accurate instrument tracking without the need for markers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If marker-based optical tracking is used, then real-time instrument location can be obtained, but line-of-sight blockage disables tracking or degrades performance
Solution Approach 1:
The patent replaces optical tracking systems with electromagnetic field-based tracking. Instead of using optical markers that require line-of-sight, the invention employs EM sensors and transmitters that operate through electromagnetic fields, allowing tracking without visual line-of-sight and eliminating the harmful effect of physical blockage.
Solution Approach 2:
The patent introduces electromagnetic fields as an intermediary medium for tracking. Rather than direct optical detection requiring line-of-sight, EM fields serve as the mediator that carries tracking information through the body and surrounding tissues, enabling tracking even when direct visual path is blocked.
2Ease of operation
If electromagnetic tracking is used, then line-of-sight problems are avoided, but tracking accuracy is degraded by external EM fields
Solution Approach 1:
The patent divides the electromagnetic tracking system into multiple independent components: separate transmitters on the instrument and sensors in the imaging system. This segmentation allows the system to distinguish between actual instrument signals and external EM interference, improving accuracy while maintaining continuous tracking availability.
Solution Approach 2:
The patent implements feedback mechanisms where the tracking system continuously monitors EM field conditions and adjusts its operation accordingly. By detecting external EM field interference and compensating through feedback control, the system maintains tracking accuracy even in the presence of external electromagnetic disturbances.
3Loss of information
If pre-procedural imaging is used to identify targets, then anatomical structures can be visualized, but real-time instrument location relative to anatomy remains uncertain
Solution Approach 1:
The patent merges the imaging system and tracking system into a single integrated system. The EM tracking sensors are incorporated into the imaging system itself, allowing simultaneous acquisition of anatomical images and instrument location data in the same coordinate system. This merging eliminates the information loss and uncertainty by providing real-time co-registered visualization of both anatomy and instrument position.
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 solution enables precise, real-time tracking of instruments within anatomical structures, reducing uncertainties and patient risks by providing accurate location and orientation data of functional parts, even in environments with electromagnetic distortions, and allowing for multiple instruments to be tracked simultaneously.
Implementation Method 1
Optical shape sensing can involve backscattering from Fiber Bragg Gratings ('FBGs') as well as Rayleigh scatterers in the cores or cladding of optical fibers
Implementation Method 2
Optical shape sensing can involve backscattering from Fiber Bragg Gratings ('FBGs') as well as Rayleigh scatterers in the cores or cladding of optical fibers
Data Source
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Figure 5A~5C
AI summary
A system and method are provided for tracking a functional part of an instrument during an interventional procedure and displaying dynamic imaging corresponding to a functional part of the instrument. The system comprises: at least one instrument; a system for acquiring anatomical images relevant to guiding the instrument;a tether connected to the imaging system at a fixed end and connected to the instrument at a distal end, the tether comprising at least one longitudinal optical fiber with a plurality of optical shape sensors; an optical console that interrogates the sensors and detects reflected light; and a processor that calculates local curvature at each sensor location to determine the three-dimensional shape of the tether and determines the location and orientation of the instrument relative to the images using the local curvatures of the tether and the location of the fixed end of the tether.