Adaptive Filter for Bioelectric Signal Interference Reduction
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Solution Overview
Problem
Magnetic fields from rotating medical imaging systems, such as CT systems, cause interferences in bioelectric signal measurements, making it difficult to identify features like the T-wave and P-wave in electrocardiograms during imaging processes.
Innovation Solution
A filter method and apparatus that capture the gantry rotation frequency, generate a virtual reference signal, and use an adaptive filter to estimate and subtract interference signals from bioelectric signals, improving signal quality without requiring additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a magnetic field is generated for medical imaging (CT system), then imaging capability is improved, but interference in bioelectric signal measurement increases
Solution Approach 1:
The patent introduces a magnetic field sensor as an intermediary device that detects the magnetic field generated by the CT system. This sensor acts as a mediator between the CT system and the EKG measurement system, capturing the interference signal so it can be processed and removed through adaptive filtering, thereby resolving the conflict between maintaining imaging capability and reducing interference.
2Measurement precision
If adaptive filtering is applied to remove interference, then signal quality is improved, but system complexity increases
Solution Approach 1:
The patent implements feedback by using the magnetic field sensor to continuously monitor the magnetic field environment and feed this information back to the adaptive filter. The adaptive filter then adjusts its filtering parameters in real-time based on the detected interference, creating a closed-loop system that improves signal quality while keeping the complexity manageable through automated adaptation.
Solution Approach 2:
The adaptive filtering system performs self-service by automatically adjusting its own parameters based on the magnetic field sensor input. The system self-regulates the filtering process without requiring manual intervention, selecting appropriate filter types (notch, band-stop, band-pass) and parameters based on the detected interference characteristics, thereby improving signal quality while minimizing operational complexity.
3Measurement precision
If additional sensors are added to detect magnetic field frequency, then interference detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent applies multi-functionality by designing the magnetic field sensor to serve multiple purposes: it detects the magnetic field frequency, determines the rotation frequency of the CT gantry, and provides input for the adaptive filtering process. This single sensor performs what would otherwise require multiple separate measurement systems, thereby improving interference detection accuracy while minimizing the increase in device complexity.
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 effectively reduces interference signals, enhancing the accuracy of bioelectric signal measurements and allowing for more precise control of medical imaging systems by filtering out magnetic field-induced noise.
Implementation Method 1
a magnetic field may already result, which penetrates the patient virtually homogeneously and can thus cause interferences in the EKG signal
Data Source
AI summary
A filter method for reducing interferences of a measuring signal, caused by magnetic fields of a rotatable medical imaging system while measuring bioelectric signals in a differential voltage measuring system, the filter method including: capturing a frequency value of a rotation of a gantry of the rotatable medical imaging system; generating a virtual reference signal as a function of the frequency value captured; estimating, via an adaptive signal filter, an amplitude and a constant phase offset of an estimated interference signal, based upon the virtual reference signal generated and a measuring signal; and filtering the measuring signal with the adaptive signal filter by subtracting the estimated interference signal from the measuring signal. A filter apparatus is also described. Furthermore a voltage measuring system is described. Furthermore, a rotating medical imaging system is described.