Low-Frequency Electromagnetic Tracking for Deep Instrument Positioning
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Solution Overview
Problem
Accurately tracking the position of medical instruments within the body, particularly when they are deep within large patients, is challenging due to interference from the earth's magnetic field and other man-made sources, and existing systems struggle to generate a strong and stable magnetic field without causing tissue disruption.
Innovation Solution
A low-frequency electromagnetic tracking system using a medical instrument with a ferromagnetic core and inductor coil generates a magnetic field detectable by sensors outside the body, allowing real-time tracking of the instrument's position, orientation, and motion through a control circuit and sensor system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-frequency electromagnetic signals are used for tracking, then the magnetic field strength is improved, but tissue disruption and heating effects worsen
Solution Approach 1:
The patent changes the frequency parameter from conventional high-frequency (MHz range) to low-frequency (below 100 Hz) electromagnetic signals. This parameter change allows generation of sufficient magnetic field strength for deep tissue tracking while avoiding the harmful heating and disruption effects associated with high-frequency signals. The low-frequency excitation produces a magnetic field that penetrates deep into the body without causing tissue damage.
2Length of stationary object
If deep tracking within large patients is achieved, then tracking depth is improved, but signal detection precision worsens due to interference
Solution Approach 1:
The patent converts the harmful effect of deep tissue penetration (which normally attenuates and distorts signals) into a benefit by using low-frequency electromagnetic signals that naturally penetrate deep into the body with minimal attenuation. The low-frequency signals pass through large patients and deep tissues without significant loss, maintaining detection precision even at deep tracking depths where high-frequency signals would fail.
3Object-affected harmful factors
If low-frequency electromagnetic signals are used, then tissue safety is improved, but magnetic field strength and detectability worsen
Solution Approach 1:
The patent employs dynamic signal processing techniques including modulation of the low-frequency electromagnetic signals and sophisticated detection algorithms. The system dynamically adjusts excitation parameters and uses signal processing to amplify and extract the weak low-frequency signals from background noise, maintaining sufficient detectability while preserving tissue safety.
Solution Approach 2:
The patent introduces a ferromagnetic core as an intermediary element within the medical instrument. This core concentrates and amplifies the low-frequency magnetic field generated by the excitation coil, significantly enhancing the magnetic field strength and detectability without requiring high-frequency signals that would compromise tissue safety.
4Measurement precision
If conventional high-frequency tracking is used, then signal detectability is improved, but the ability to track deep within body worsens due to signal attenuation
Solution Approach 1:
The patent fundamentally changes the frequency parameter from high-frequency (MHz) to low-frequency (below 100 Hz) electromagnetic signals. This parameter change exploits the physical property that low-frequency electromagnetic waves experience minimal attenuation in biological tissues, enabling effective tracking at depths of 30 cm or more while maintaining signal detectability through sophisticated detection algorithms.
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
Enables precise tracking of medical instruments within the body, even at depth, by distinguishing the generated magnetic field from noise and interference, ensuring accurate medical procedures and patient safety.
Implementation Method 1
an inductor coil wrapped around a core... The inductor coil is configured to receive an excitation signal having a frequency below 10,000 Hz... The inductor coil and the core are configured to generate a magnetic field based in part on the current
Implementation Method 2
A low-frequency electromagnetic tracking system using a medical instrument with a ferromagnetic core and inductor coil generates a magnetic field detectable by sensors outside the body
Data Source
Figure 1
Figure 2A
Figure 2B~2C
AI summary
A medical system tracks the position of a medical instrument within a body of a patient. The medical instrument includes an electromagnet structure having an inductor coil wound around a core. A control circuit applies a low frequency excitation signal across the inductor coil. The inductor coil and the core generate a magnetic field. A plurality of sensors sense parameters of the generated magnetic field and produce sensor signals. The control circuit calculates the position of the medical instrument based on the produced sensor signals.