MRT Patient Table Positioning for SAR Optimization
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Solution Overview
Problem
Magnetic resonance tomographs (MRTs) face challenges in optimizing specific absorption rate (SAR) performance, leading to potential exceeding of permissible SAR limits during scanning, which can result in suboptimal image quality and prolonged scan times due to the need to adjust measurement programs to comply with SAR limits.
Innovation Solution
The method involves determining the optimal position of the patient table relative to the RF transmission coil by displacing it along the z, y, or x axes to minimize SAR values, allowing for adjustments in RF amplifier drive amplitude and power to maintain within permissible limits while ensuring optimal image quality and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the RF amplifier drive amplitude and power are increased to improve image quality and reduce scan time, then the SAR values increase and may exceed permissible limits
Solution Approach 1:
The patent applies preliminary action by determining the optimal position of the patient table relative to the RF transmission coil before initiating the MRT scan. The patient table is displaced along the z, y, or x axes to a position that minimizes SAR values, ensuring that subsequent scanning operations can proceed with optimized RF parameters without exceeding permissible SAR limits, thus enabling faster and higher-quality scans.
Solution Approach 2:
The patent utilizes parameter changes by adjusting the position parameters of the patient table along the z, y, or x axes to optimize SAR performance. By changing the spatial position parameter, the system achieves minimal SAR values while maintaining image quality, allowing for reduced RF amplifier drive amplitude and power requirements.
2Object-affected harmful factors
If the measurement program is adjusted to comply with SAR limits, then SAR performance is optimized, but scan time increases and image quality deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-determining the optimal patient table position that minimizes SAR values before the actual scanning begins. This preliminary positioning eliminates the need for time-consuming adjustments during the scan to comply with SAR limits, as the system is already configured to operate within permissible SAR constraints while maintaining optimal imaging parameters.
Solution Approach 2:
The patent replaces mechanical adjustment procedures with a positioning optimization approach. Instead of mechanically adjusting RF amplifier parameters or scan sequences to comply with SAR limits, the system substitutes this with optimizing the patient table position, thereby reducing adjustment time and maintaining scan efficiency.
3Object-affected harmful factors
If the patient table position is optimized to minimize SAR values, then SAR performance improves, but the complexity of positioning and parameter adjustment increases
Solution Approach 1:
The patent utilizes parameter changes by systematically varying the patient table position along the z, y, or x axes to identify the optimal position that minimizes SAR values. This parameter optimization approach, while requiring positioning adjustments, simplifies the overall system complexity by focusing on a single critical parameter (position) rather than multiple interdependent RF parameters.
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 enables the optimization of SAR performance by identifying positions that minimize SAR exposure, allowing for faster and higher-quality scans by adjusting RF parameters, thereby reducing the need for time-consuming adjustments and ensuring compliance with SAR limits.
Implementation Method 1
a radiofrequency antenna represented here in a very simplified way as a (e.g., multipart=108a, 108b, 108c) body coil 108
Implementation Method 2
A strong magnet (often a cryomagnet 107) in a measurement space, here with a tunnel-shaped opening 103, generates a strong static main magnetic field B0
Implementation Method 3
The gradient coils 112x, 112y, 112z, with which gradient magnetic fields BG(x, y, z, t) are applied during a measurement for selective slice excitation and for position encoding of the measurement signal
Data Source
AI summary
The embodiments relate to devices and methods for MRT imaging with a MRT, where a patient table having the scan subject is moved in at least one direction along at least one displacement path, determination of a quantity representing the SAR effect on the scan subject being carried out at a plurality of positions along the displacement path, a suitable position of the patient table, lying on a displacement path, being determined, at which the MRT imaging of the scan subject imaging region, to be scanned, of the scan subject is subsequently intended to be carried out.