Magnetic Marker Detection With Harmonic Filtering for Surgical Guidance
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Solution Overview
Problem
Existing magnetic marker detection systems struggle to accurately distinguish between magnetic markers and tracers, particularly in the presence of metallic tools, human tissue, and multiple markers, due to interference from harmonics and linear responses, which complicates surgical procedures.
Innovation Solution
A magnetic detection system using a probe with a harmonic filter and drive circuit generates a pure single-frequency magnetic field, and a sense coil detects non-linear harmonic responses from markers, while filtering out fundamental and spurious frequencies to isolate the marker signal, employing a correction factor to distinguish between markers and tracers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a magnetic detection system uses a probe to detect both magnetic markers and iron oxide nanoparticle tracers, then both can be detected simultaneously, but the system cannot distinguish between the marker signal and tracer signal
Solution Approach 1:
The patent applies periodic action by using alternating magnetic fields at different frequencies to excite the marker and tracer separately. The marker is excited at a first frequency while the tracer responds at a second frequency, allowing temporal separation of detection signals. This periodic excitation at distinct frequencies enables the system to distinguish between marker and tracer responses despite both being present in the tissue.
Solution Approach 2:
The patent changes the frequency parameter of the alternating magnetic field to differentiate between marker and tracer detection. By operating at different frequency ranges (first frequency for marker, second frequency for tracer), the system transforms a single-frequency detection problem into a multi-frequency solution, allowing simultaneous presence of both materials to be resolved through frequency-selective measurement.
2Reliability
If a magnetic marker detection system operates in the presence of metallic surgical tools, then the marker can be detected, but metallic tools create interference signals that reduce detection accuracy
Solution Approach 1:
The patent introduces frequency as an intermediary parameter to separate the marker signal from metallic tool interference. By detecting the marker at a specific frequency range distinct from the interference frequencies generated by metallic tools, the system uses frequency selection as a mediator to isolate the desired signal from harmful electromagnetic interference in the surgical environment.
3Measurement precision
If a high magnetic field strength is used to improve marker detection sensitivity, then detection distance increases, but harmonics are generated that interfere with signal detection
Solution Approach 1:
The patent extracts the harmful harmonic components from the detection signal by using frequency filtering. The system separates the fundamental frequency signal (containing the marker information) from the harmonic frequencies (containing interference), removing only the harmful harmonic portions while preserving the useful fundamental signal for accurate marker detection.
Solution Approach 2:
The patent uses periodic modulation at a specific drive frequency to excite the marker, creating a known fundamental frequency signal. By establishing this periodic reference, the system can distinguish between the periodic fundamental signal (desired) and non-periodic or differently-periodic harmonic distortions (undesired), enabling selective enhancement of sensitivity while filtering harmonics.
4Ease of operation
If a handheld magnetic probe is used for real-time marker localization during surgery, then surgical guidance is provided, but the probe responds to multiple magnetically responsive materials simultaneously
Solution Approach 1:
The patent changes the frequency parameter of the alternating magnetic field to achieve signal specificity while maintaining real-time operation. By switching between different frequency ranges (first frequency for marker, second frequency for tracer), the handheld probe can selectively query for specific material types in real-time, providing surgical guidance with material-specific information rather than generic magnetic responses.
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 enhances the accuracy of marker localization, allowing for precise surgical procedures by distinguishing between markers and tracers, reducing tissue removal errors and improving surgical outcomes.
Implementation Method 1
A magnetic detection system using a probe with a harmonic filter and drive circuit generates a pure single-frequency magnetic field
Implementation Method 2
the marker comprises at least one piece of magnetically responsive material and has a non-linear magnetic susceptibility
Implementation Method 3
A marker that can be accurately localized against the backdrop signal from the human body is therefore advantageous
Implementation Method 4
a sense coil detects non-linear harmonic responses from markers
Implementation Method 5
filtering out fundamental and spurious frequencies to isolate the marker signal
Data Source
AI summary
A method for detecting a magnetic marker comprises generating a driving magnetic field comprising first and second frequencies and detecting a response magnetic field comprising first and second response components. The magnetic marker provides a non-linear response to the driving signal. A primary portion of the response components is generated by the magnetic marker, and a secondary portion of the response components is generated by a secondary magnetic source. The method comprises determining a driving factor representing a ratio of the frequencies in the driving signal; determining a correction factor corresponding to the secondary portion of the second response component, based on the first response component and the driving factor; determining a detection signal corresponding to the primary portion of the second response component, based on the second response component and the determined correction factor; and generating an output signal based on a strength of the detection signal.