Multichannel RF Signal Generation for MR Systems
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Solution Overview
Problem
Magnetic Resonance (MR) systems face challenges in the stability and compact implementation of RF excitation signal generation, particularly in generating complex RF pulses and managing heat dissipation, which affects the fidelity and efficiency of RF excitation signals.
Innovation Solution
A multichannel system with RF power amplifiers, synthesizers, and feedback loops is employed, where each channel has a local feedback loop for signal control and a global feedback loop for combining signals, allowing for advanced heat dissipation and the generation of complex RF pulses by distributing power generation units, optimizing signal characteristics, and improving phase and time synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single power generation unit is used to generate RF excitation signals, then the system structure is simple, but the system cannot generate complex RF pulses and has poor heat dissipation management
Solution Approach 1:
The patent divides the RF signal generation system into multiple independent power generation units (first power generation unit and second power generation unit), each capable of generating RF signals with different characteristics. This segmentation allows the system to generate complex RF pulses by combining signals from multiple units while maintaining manageable complexity in each individual unit.
Solution Approach 2:
The patent combines RF signals from multiple power generation units through a combiner to produce the final RF excitation signal. This merging capability enables the system to generate complex RF pulses that cannot be produced by a single unit, while the combiner integrates the signals in a way that maintains overall system coherence.
2Volume of moving object
If a single power generation unit generates high power RF signals, then the system is compact, but heat dissipation becomes difficult to manage
Solution Approach 1:
The patent segments the high power RF signal generation into multiple lower-power units, each handling a portion of the total power. This distribution reduces the thermal load on each individual unit, making heat dissipation more manageable while the combined output achieves the required high power level for RF excitation.
3Adaptability or versatility
If multiple power generation units are used to generate RF signals, then complex RF pulses can be generated and heat dissipation is improved, but the system complexity increases
Solution Approach 1:
The patent segments the RF signal generation function across multiple units, each with standardized interfaces and control mechanisms. This segmentation enables complex pulse generation through coordinated operation of independent units while maintaining modular architecture that simplifies overall system management.
Solution Approach 2:
The patent incorporates feedback mechanisms where the controller receives information about the RF signals generated by each power generation unit and adjusts their operation accordingly. This feedback control enables precise coordination of multiple units to generate complex RF pulses while automatically managing system complexity through intelligent control.
4Manufacturing precision
If RF signal characteristics are precisely controlled in each channel, then signal fidelity is improved, but the control system complexity increases
Solution Approach 1:
The patent implements feedback loops in each power generation unit where the controller monitors RF signal characteristics (amplitude, phase, frequency) and adjusts the unit's operation to maintain precise control. This feedback mechanism enables high signal fidelity while the automated control reduces the burden of manual precision adjustment.
Solution Approach 2:
The patent controls RF signal characteristics by dynamically changing operational parameters (voltage, current, frequency) of each power generation unit based on the desired signal profile. This parameter-based control allows precise signal characterization adjustment through software-controlled parameter modulation rather than hardware complexity.
Data Source
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AI summary
The invention provides for a system (200) for generation of a radio frequency, RF, excitation signal for excitation of nuclei via an RF excitation coil (114) in a magnetic resonance system (100). The system comprises power generation units (203-206) each comprising a synthesizer (211-214), an RF amplifier (231-234), and a first feedback loop (251-254) unit adapted to configure the synthesizer to generate an RF signal which after amplification by the RF amplifier has a predefined first signal characteristic and a combiner (261) adapted for combining the RF signals amplified by the RF amplifiers for obtaining the RF excitation signal.