Systems and methods for improved electromagnetic tracking
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Solution Overview
Problem
Existing electromagnetic (EM) navigation systems face challenges in accurately tracking the pose of vertebrae during spinal corrective surgery due to magnetic and conductive distortions caused by ferromagnetic materials and surgical instruments, which limit navigation volume and range.
Innovation Solution
A bi-directional EM navigation system using micro-coils that function as both transmitters and receivers, combined with spread-spectrum signaling, reduces distortions by minimizing magnetic field strength and correcting conductive distortions, thereby expanding navigation volume and range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If traditional EM navigation systems use macro-coil transmitters and mini-coil receivers, then navigation coverage area is large, but magnetic and conductive distortions increase significantly
Solution Approach 1:
The patent divides the navigation system into multiple micro-coils distributed throughout the surgical site, each acting as both transmitter and receiver. This segmentation replaces the traditional single macro-coil transmitter with numerous small micro-coils, reducing individual magnetic field strength while maintaining collective navigation coverage through distributed sensing.
Solution Approach 2:
Each micro-coil in the array performs dual functions as both transmitter and receiver, eliminating the need for separate macro-coil transmitters and mini-coil receivers. This multi-functionality reduces the overall magnetic field strength required while maintaining navigation capabilities, thereby reducing magnetic and conductive distortions.
2Object-affected harmful factors
If micro-coils are used as both transmitters and receivers, then distortion is reduced, but navigation volume and range are limited
Solution Approach 1:
The patent combines multiple micro-coils into a distributed array that functions collectively as both transmitter and receiver systems. By merging the capabilities of multiple micro-coils, the system achieves extended navigation volume and range while maintaining low individual magnetic field strengths that reduce distortion.
Solution Approach 2:
The system transitions from traditional three-dimensional spatial navigation to four-dimensional navigation by incorporating temporal dimension through sequential activation of micro-coils in the array. This allows extended navigation volume and range without increasing individual magnetic field strength, as the system leverages time-multiplexed sensing across multiple coil positions.
3Object-affected harmful factors
If magnetic field strength is minimized, then distortion is reduced, but signal detection precision deteriorates
Solution Approach 1:
The system employs feedback mechanisms where each micro-coil's received signals from neighboring micro-coils are processed to determine relative positions and orientations. This feedback loop allows the system to compensate for low signal strength through iterative position determination and distortion correction algorithms, maintaining measurement precision despite minimized magnetic field strength.
Solution Approach 2:
The patent implements preliminary calibration and distortion mapping before actual navigation procedures. By pre-characterizing the magnetic and conductive distortion environment and storing correction factors, the system can compensate for low signal strength during navigation without requiring high magnetic field strength, thereby maintaining measurement precision while minimizing distortion.
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
The system effectively tracks the pose of vertebrae in multiple degrees of freedom, providing accurate real-time alignment during spinal surgery by significantly reducing magnetic and conductive distortions, while maintaining a clinically relevant navigation volume and range.
Implementation Method 1
Each of the plurality of bi-directional micro-coils is configured to generate an electromagnetic field
Implementation Method 2
detect at least one of the generated electromagnetic fields at a neighboring bi-directional micro-coil
Data Source
AI summary
Tracking a pose of a portion of an anatomical structure using a bi-directional electromagnetic navigation system may include generating a signal comprising a plurality of frequencies. The signal may be received at a bi-directional coil array that comprises a plurality of bi-directional micro coils configured to both generate electromagnetic fields and detect electromagnetic fields generated by neighboring bi-directional micro coils. Each of the plurality of bi-directional micro coils may be coupled to a portion of a structure. In response to receiving the signal, an electromagnetic field may be generated at each of the plurality of bi-directional micro coils. At least one of the generated electromagnetic fields may be detected at a neighboring bi-directional micro coil of a bi-directional micro coil that is generating the at least one detected electromagnetic field. A pose of the bi-directional micro coil that is generating the at least one detected electromagnetic field may be determined.