Gradient Coil Resonance Control via Electrical Model
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Solution Overview
Problem
Magnetic resonance tomography systems face issues with mechanical resonance in gradient coils, leading to noise, vibration, and potential damage, as well as image artifacts and helium evaporation, due to the inability to accurately assess the amplitude of resonance excitation in existing frequency exclusion methods.
Innovation Solution
A method using an electrical resonant circuit model to determine and prevent mechanical resonance by simulating the coil's response to varying currents, considering the amplitude of each frequency component, and blocking current flow if the resonance exceeds a predefined limit, with a monitoring module that integrates this model to check gradient pulse sequences for potential resonance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequency bands are excluded to avoid mechanical resonance, then coil damage and noise are reduced, but imaging sequences are unnecessarily restricted and productivity decreases
Solution Approach 1:
The patent changes the parameter assessment from binary frequency exclusion to continuous amplitude evaluation. By calculating the actual resonance amplitude caused by each gradient pulse sequence and comparing it against a threshold, the system dynamically adjusts which sequences are permitted based on their specific amplitude characteristics rather than excluding entire frequency bands.
Solution Approach 2:
The system transitions from static frequency band exclusion to dynamic amplitude-based decision making. The monitoring module continuously evaluates the resonance amplitude for each requested gradient pulse sequence and makes real-time decisions about sequence execution, allowing the system to adapt to different imaging requirements while maintaining safety.
2Productivity
If amplitude-based resonance detection is implemented, then unnecessary frequency restrictions are eliminated, but device complexity increases
Solution Approach 1:
The patent replaces complex physical monitoring hardware with a computational model. Instead of using additional sensors and mechanical monitoring devices to detect resonance, the system uses an electrical resonant circuit model that calculates resonance amplitude based on gradient pulse sequence parameters, substituting physical measurement with mathematical simulation.
Solution Approach 2:
The system creates a virtual copy of the resonant circuit behavior through mathematical modeling. By simulating the electrical resonant circuit's response to different gradient pulse sequences, the system can predict mechanical resonance amplitudes without physically measuring them, using a simplified computational representation of the complex physical system.
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 prevents damaging resonances by considering the amplitude of each frequency component, reducing noise and vibration, and ensuring safe operation of magnetic resonance tomography systems while allowing for optimal imaging sequences without unnecessary restrictions on frequency bands.
Implementation Method 1
An electric current always produces a magnetic field. In an electric coil, this magnetic field is especially marked. If another external magnetic field is present, an interaction results, and an attraction or repulsion of the coil results.
Implementation Method 2
The problem of mechanical resonance in the gradient coils arises, for example, in the case of very rapid magnetic resonance tomography imaging technology
Data Source
AI summary
A method for operating a coil, through which a varying current flows, is provided. Mechanical resonance responses of the coil are recorded and are modeled by an electrical resonant circuit model. A check is made as to whether a varying current that is to be sent through the coil evokes a resonant response in the electrical resonant circuit model. The current flow through the coil is blocked if the resonant response exceeds a predefined limit value.