MR Gradient Field Center Calibration Using Magnetic Flux Measurement
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Solution Overview
Problem
Calibrating the center of a gradient field domain in magnetic resonance (MR) devices is challenging due to the risks of quenching and high economic costs associated with field-raising/field-lowering operations, and existing methods are inefficient for MR image-guided radiotherapy.
Innovation Solution
A method and system using a magnetic flux measurement component to switch gradient fields, determine the center of the gradient field domain, and perform mechanical adjustments to accurately calibrate the MR device without field-raising/field-lowering, and adjust image reconstruction processes to correct inaccuracies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If field-raising/field-lowering operations are performed to calibrate the gradient field domain center, then calibration accuracy is improved, but the risk of quenching increases and economic costs rise due to liquid nitrogen consumption
Solution Approach 1:
The patent replaces the mechanical field-raising/field-lowering operation with an electromagnetic measurement approach. A magnetic flux measurement component (such as a Hall sensor or fluxmeter) is used to directly measure the magnetic flux distribution in the gradient field domain, allowing the center to be determined through measurement and calculation rather than through mechanical field adjustment. This substitution eliminates the quenching risk associated with moving the superconducting magnet while maintaining calibration accuracy.
Solution Approach 2:
The patent introduces a magnetic flux measurement component as an intermediary tool between the gradient field and the calibration process. This intermediary device enables indirect measurement of the gradient field center through magnetic flux distribution analysis, avoiding the need for direct mechanical intervention that causes quenching. The measurement component acts as a mediator that translates magnetic field information into usable calibration data without requiring field movement.
2Measurement precision
If field-raising/field-lowering operations are performed for calibration, then gradient field center accuracy is improved, but economic costs increase due to liquid nitrogen consumption
Solution Approach 1:
The patent replaces the energy-intensive mechanical field-raising/field-lowering process with a low-power electromagnetic measurement system. By using magnetic flux sensors and computational methods to determine the gradient field center, the system avoids the substantial liquid nitrogen consumption required for superconducting magnet field adjustments, thereby maintaining calibration accuracy while dramatically reducing operational costs.
Solution Approach 2:
The patent creates a measurement model of the magnetic flux distribution that serves as a copy or representation of the actual gradient field characteristics. By analyzing this measured flux distribution pattern, the system can determine the gradient field center without physically moving the magnet. This copying approach allows calibration to be performed through data analysis rather than energy-consuming mechanical operations.
3Measurement precision
If multiple measurements are performed to account for absolute error in magnetic field measurement, then measurement accuracy is improved, but calibration time increases
Solution Approach 1:
The patent performs preliminary characterization of the magnetic flux measurement component's error characteristics before the actual calibration process. By establishing correction factors or calibration curves in advance through initial measurements, the system can compensate for absolute errors during the main calibration operation without requiring multiple repeated measurements, thus reducing total calibration time while maintaining accuracy.
Solution Approach 2:
The patent implements a feedback mechanism where the magnetic flux measurement results are continuously refined through iterative correction based on known reference values or previously established error models. The system uses the measured magnetic flux distribution, applies correction algorithms to account for measurement component errors, and adjusts the determination of the gradient field center accordingly. This feedback-based error compensation allows accurate calibration in a single measurement pass rather than requiring multiple measurements.
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
Accurately calibrates the MR device center without quenching risks and reduces economic costs, enhancing the precision of MR image-guided radiotherapy.
Implementation Method 1
obtaining, by using a magnetic flux measurement component, a magnetic flux variation in the at least one gradient direction
Data Source
AI summary
A method for calibrating a medical device is provided. The medical device may include a magnetic resonance (MR) device. The method may include switching a gradient field in at least one gradient direction of the MR device; obtaining a magnetic flux variation in the at least one gradient direction in at least one portion of a spatial region within a gradient field domain of the MR device using a magnetic flux measurement component; determining a center of the gradient field domain of the MR device based on the magnetic flux variation; and performing a mechanical adjustment on the MR device to locate the center of the gradient field domain at a target position based on the center of the gradient field domain, or adjusting an image reconstruction process to correct or eliminate an impact of inaccuracy of the center of the gradient field domain on a reconstructed image.