Multi-Frequency EM Navigation for Metallic Distortion Correction
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Solution Overview
Problem
Medical navigation systems face position and orientation errors due to metallic objects in the field, which are unpredictable and difficult to compensate for, leading to incorrect device placement during surgical or interventional procedures.
Innovation Solution
A navigation system that uses electromagnetic sensors to generate and detect electromagnetic fields at multiple frequencies, calculating distortions caused by metallic objects based on signal responses and distance between sensors, allowing for correction of position and orientation errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If electromagnetic sensors are used to acquire position and orientation information, then navigation capability is enabled, but position and orientation errors occur due to metallic objects causing field distortion
Solution Approach 1:
The system transmits electromagnetic fields at multiple different frequencies to the sensors. By analyzing how the field distortion varies with frequency, the system can characterize the distortion caused by metallic objects and compensate for it, thereby maintaining position and orientation accuracy despite the presence of metal in the surgical field
Solution Approach 2:
The system measures the actual electromagnetic field received by sensors at multiple frequencies, compares it with expected field characteristics, and uses this feedback to calculate and apply distortion compensation. This closed-loop approach allows real-time correction of position and orientation data affected by metallic objects
2Measurement precision
If distortion compensation is attempted using traditional methods, then position accuracy may be improved, but the unpredictability of metallic object parameters makes compensation difficult
Solution Approach 1:
Instead of requiring detailed knowledge of metallic object parameters (shape, size, composition), the system changes the frequency parameter of the electromagnetic field and measures how the distortion responds. This allows characterization of the distortion effect without needing to know the specific properties of the metallic objects, simplifying the compensation approach
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 compensates for field distortions caused by metallic objects, providing accurate position and orientation data for medical devices, even in environments with conductive materials, thereby improving the precision of medical procedures.
Implementation Method 1
driving a transmitter at a first frequency and at least a second frequency to generate a first and a least a second electromagnetic field
Implementation Method 2
receiving a first and at least a second distorted field corresponding to the first and second electromagnetic fields, respectively, with each of at least two electromagnetic (EM) sensors attached to a surgical device
Data Source
AI summary
A method performed in a medical navigation system includes driving a transmitter at a first frequency and a second frequency to generate first and second electromagnetic fields, wherein the first and second frequencies are sufficiently low such that the first and second electromagnetic fields are frequency independent; receiving first and second distorted fields corresponding to the first and second electromagnetic fields, respectively, with each of at least two electromagnetic (EM) sensors attached to a surgical device; generating first and second signals in response to receiving the first and second distorted fields, respectively, using each of the at least two EM sensors; and determining a distortion in the first and second signals based at least on a distance between the at least two EM sensors and a difference between the first and second signals generated by each of the at least two EM sensors.