Optical Fiber Shape Sensing for 3D Anatomical Mapping
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Solution Overview
Problem
Existing tomography techniques face challenges in accurately determining the absolute position and angle of optical sources within anatomical targets, particularly due to the large size and intrusive nature of current machines.
Innovation Solution
A paired shape sensing fiber and single-core fiber system is used to provide three-dimensional scanning capabilities inside and outside anatomical targets. The shape sensing fiber offers precise position and orientation information, while the single-core fiber provides distance measurements using optical frequency domain reflectometry (OFDR) technology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional tomography machines (CAT, PET, MRI) are used to obtain projection data from multiple directions, then accurate three-dimensional imaging is achieved, but the machines are too large and intrusive to be placed inside anatomical targets
Solution Approach 1:
The patent divides the traditional large-scale tomography system into distributed optical fiber sensors that can be inserted into the anatomical target. Multiple fiber optic sensors are positioned at different locations to collectively provide the multi-directional measurement capability previously requiring a single large machine
Solution Approach 2:
The patent uses optical fiber as an intermediary carrier to transmit measurement data from inside the anatomical target to external processing systems. The fiber optic sensors act as mediators that bridge the gap between the internal measurement environment and external analysis equipment
2Length of stationary object
If OCT probes are placed inside anatomical targets to scan tissue, then deeper tissue penetration is achieved, but the measuring range is still limited to millimeters
Solution Approach 1:
The optical fiber sensor system serves multiple functions: it provides both shape/position sensing and enables extended measuring range through its flexibility. The same fiber infrastructure supports both localization and extended reach into deeper tissues without requiring separate probe insertion procedures
3Measurement precision
If FaroArm machines with high-resolution encoders are used to measure three dimensional locations and angles, then precise position and orientation data is obtained, but the machines are too large and intrusive for operating room use
Solution Approach 1:
The patent replaces the mechanical encoder-based measurement system with an optical-based sensing system. Instead of using mechanical hinged segments with encoders, the system uses optical fiber strain sensing to detect position and orientation changes through optical interference patterns
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 enables accurate three-dimensional mapping of tissue surfaces and subsurface features with a small, inexpensive, and unobtrusive device, overcoming the limitations of current tomography techniques by allowing for deeper tissue penetration and greater measuring range.
Implementation Method 1
Optical strain sensing is useful for measuring physical deformation of an optical fiber caused by, for example, the change in tension, compression, or temperature of the optical fiber. A continuous measure of strain along the length of a core can be derived by interpreting the optical response of the core using swept wavelength interferometry.
Implementation Method 2
In a technique known as optical position and/or shape sensing detailed in commonly-assigned U.S. patent 8,773,650 to Froggatt et al., entitled 'Optical Position and/or Shape Sensing ', this strain profile information is used to reconstruct the three dimensional position of the fiber.
Implementation Method 3
The shape sensing fiber offers precise position and orientation information, while the single-core fiber provides distance measurements using optical frequency domain reflectometry (OFDR) technology.
Data Source
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Figure 7
AI summary
A fiber housing includes multiple shape sensing cores and a single optical core. A distal end of the fiber housing is positionable to direct the single optical core to a current point of an anatomical target. Collimated light over a first range of frequencies is projected from the single optical core to the current point. OFDR is used to detect reflected light scattered from the current point and to process the detected light to determine a distance to the current point. Light over a second range of frequencies is projected through the multiple shape sensing optical cores to the distal end of the fiber housing. OFDR is used to measure light reflected from the distal end of the fiber housing back through the multiple shape sensing optical cores and to process the measurement to determine a position in three dimensional space of the distal end of the fiber housing and a pointing direction of the distal end of the fiber housing. A position in three dimensional space of the current point is determined based on the determined position in three dimensional space of the distal end of the fiber housing, the pointing direction of the distal end of the fiber housing, and the determined distance.