RF Coil Detuning Circuit Using Impedance Resonance
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Solution Overview
Problem
Existing RF coil detuning methods in MRI systems rely on high-power diodes, which are expensive and prone to breakdown due to frequent control operations, leading to cost issues and potential device failure.
Innovation Solution
An RF coil tuning/detuning structure that connects the RF coil to an impedance circuit via an RF line to change its electrical structure, eliminating the need for switch elements and reducing costs, while achieving effective detuning by matching impedance circuits and RF lines to form resonance and open circuit states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-power diodes are added on rungs of the RF coil to control detuning, then the detuning function is achieved, but the cost increases and the reliability decreases due to frequent control operations causing breakdown
Solution Approach 1:
The patent extracts the switching function from the RF coil structure by removing high-power diodes and their control circuits. Instead, it uses the inherent properties of RF lines and impedance circuits to achieve detuning without active switching components, thereby eliminating the reliability issues associated with frequent diode control operations
Solution Approach 2:
The patent introduces RF lines and impedance circuits as intermediary elements between the RF coil and the detuning mechanism. These intermediaries enable detuning through passive electrical structure changes rather than active component switching, reducing system complexity and improving reliability
2Reliability
If high-power diodes are used for detuning control, then the detuning function is achieved, but the cost increases due to the expensive nature of high-power diodes
Solution Approach 1:
The patent replaces expensive high-power diodes with cheaper passive components (RF lines and impedance circuits) that have no moving parts or active elements subject to wear or breakdown. This substitution significantly reduces both component cost and long-term maintenance costs while maintaining reliable detuning functionality
3Speed
If frequent control operations are performed on high-power diodes, then the detuning response time is improved, but the reliability deteriorates due to breakdown of the diodes
Solution Approach 1:
The patent employs periodic impedance matching and resonance techniques through RF lines to achieve rapid detuning responses. By utilizing the natural resonant properties of the RF coil and impedance circuits, the system achieves fast switching-like behavior without the need for frequent active control operations that would compromise component reliability
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 solution reduces the need for expensive high-power diodes, avoids potential breakdowns, and optimizes detuning effects by changing the RF coil's resonant frequency, preventing interference with signal reception in MRI systems.
Implementation Method 1
the first impedance circuit and the first RF line form a first equivalent inductance, and the first equivalent inductance and the first end ring capacitance form resonance, so that the first end ring capacitance is in an open circuit state
Data Source
AI summary
A tuning/detuning structure and a detuning method for an RF coil use an RF power source, a first impedance circuit, a first RF line, and a first port having a first guide leg end and a first input end, with the first guide leg end being connected to a first end ring capacitance of the RF coil. When the RF coil needs to be detuned, the first input end is connected to the first impedance circuit via the first RF line. When the RF coil needs to transmit an RF pulse signal, the first input end is connected to the RF power source via the first RF line. The need for a switch element is thereby reduced as is harm resulting from breakdown of such a switch element. An impedance circuit can be combined with a switch element to realize detuning jointly, and a good detuning effect can be achieved by a small number of switch elements.