MRI RF Coil PIN Diode Bias Control for Power Optimization
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Solution Overview
Problem
The increasing use of array coils in MRI apparatuses leads to significant power consumption by PIN diodes, which is inefficient and potentially harmful due to the need for strong transmission pulses, necessitating a solution for decoupling and protection without excessive power usage.
Innovation Solution
The implementation of a multistage bias control system for PIN diodes in RF coils, allowing for adjustable forward current values based on imaging conditions, optimizing power consumption and decoupling efficiency by switching between different bias states depending on the imaging requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a large number of coil elements are arranged in an array coil, then the imaging capability and coverage are improved, but the power consumption of PIN diodes becomes significant and inefficient
Solution Approach 1:
The patent applies parameter changes by switching the bias voltage state of PIN diodes between forward bias and reverse bias. During transmission, forward bias is applied to achieve decoupling and protect electronic components. During reception, reverse bias is applied to reduce power consumption while maintaining imaging capability. This dynamic parameter switching resolves the contradiction between maintaining imaging performance and reducing power consumption.
2Reliability
If forward current is applied to PIN diodes for decoupling and protection, then decoupling efficiency and component safety are improved, but power consumption increases significantly
Solution Approach 1:
The patent implements periodic action by switching the bias state of PIN diodes between transmission mode (forward bias for decoupling and protection) and reception mode (reverse bias for power saving). The control circuit dynamically changes the bias state according to the operational phase, achieving both reliable decoupling during transmission and reduced power consumption during reception.
Solution Approach 2:
The patent applies dynamics by making the bias state of PIN diodes adjustable and switchable rather than fixed. The power supply circuit and control circuit enable real-time switching between forward and reverse bias states, allowing the system to adapt to different operational requirements and optimize the balance between decoupling efficiency and power consumption.
3Object-affected harmful factors
If strong transmission pulses are applied to achieve decoupling and protection, then component protection is improved, but power consumption and potential harm increase
Solution Approach 1:
The patent applies preliminary anti-action by proactively switching PIN diodes to forward bias state before and during transmission pulses. This preemptive action protects electronic components from strong transmission pulses by establishing decoupling in advance, preventing potential damage while managing power consumption through controlled switching rather than continuous high-power operation.
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 reduces power consumption of PIN diodes while maintaining effective decoupling and protection of electronic components, improving the operational efficiency and safety of MRI apparatuses.
Implementation Method 1
Each active trap circuit is provided with a PIN diode. In order to decouple the coil elements or protect the coil elements, it is necessary to apply an electric current in the forward direction of the PIN diode.
Implementation Method 2
An MRI apparatus is an imaging apparatus which magnetically excites nuclear spin of an object placed in a static magnetic field with a transmission pulse of a radio frequency (RF) signal having the Larmor frequency
Implementation Method 3
reconstructs an image on the basis of magnetic resonance (MR) signals emitted from the object due to the excitation
Data Source
AI summary
In one embodiment, an MRI apparatus includes: a transmission circuit configured to apply a transmission pulse to an object; at least one radio frequency (RF) coil configured to include an active trap circuit provided with a PIN diode, and to receive a magnetic resonance signal from the object; a power supply circuit configured to apply a reverse bias voltage and a forward bias voltage to the PIN diode, and to apply multiple values of a forward current when the forward bias voltage is applied to the PIN diode; and a control circuit configured to control the power supply circuit in such a manner that the power supply circuit sets the forward current to the multiple values, depending on imaging conditions.