Magnetic Resonance Patient Bed Speed Control
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Solution Overview
Problem
High-field magnetic resonance devices cause side effects such as dizziness and metallic taste in patients due to varying magnetic field strengths during patient bed movement, which increases with higher speeds.
Innovation Solution
The patient bed is moved at a speed determined by the magnetic field distribution along its path, using a drive apparatus that adjusts speed based on field gradients or diamagnetic forces to minimize these effects, either at a constant speed or location-dependent control values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the patient bed is moved at high speed into or out of the patient chamber, then the examination time is reduced and productivity is improved, but side effects such as dizziness and metallic taste occur in patients due to varying magnetic field strengths
Solution Approach 1:
The drive apparatus dynamically adjusts the speed of the patient bed based on the local magnetic field gradient along the movement path. The speed is not constant but varies continuously to maintain a maximum diamagnetic force threshold, allowing faster movement in regions with gentle field gradients while slowing down in regions with strong gradients where side effects would occur.
Solution Approach 2:
The system changes the operational parameter (speed) of the drive apparatus as a function of the magnetic field distribution. By monitoring or pre-characterizing the magnetic field gradient along the patient bed's path, the control system adjusts the speed parameter in real-time or according to a pre-calculated profile, optimizing both patient comfort and examination efficiency.
2Reliability
If the patient bed is moved at constant high speed, then the movement process is simple and reliable, but the varying magnetic field distribution causes uncomfortable feelings in patients
Solution Approach 1:
The system implements feedback control by using information about the magnetic field distribution (either from sensors on the patient bed or from pre-measured field maps) to continuously adjust the drive apparatus speed. This closed-loop control ensures that the diamagnetic force experienced by the patient remains within comfortable limits while maintaining reliable automated operation.
Solution Approach 2:
The magnetic field distribution along the movement path is determined in advance through calibration measurements or pre-characterization. This preliminary information is stored and used to generate an optimal speed profile before the actual patient transport, allowing the system to prepare the appropriate speed adjustments without real-time delays while ensuring patient comfort.
3Object-affected harmful factors
If the speed is reduced to minimize diamagnetic forces, then patient comfort is improved, but the introduction and removal process becomes slower and less efficient
Solution Approach 1:
The speed control is applied locally based on the specific magnetic field conditions at different positions along the movement path. In regions where the magnetic field gradient is gentle, the patient bed can move at higher speeds. In regions where the gradient is strong and would cause side effects, the speed is reduced locally. This spatially-varying speed profile maintains overall efficiency while protecting patient comfort in critical zones.
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 side effects by maintaining a consistent diamagnetic force on the patient, ensuring comfortable and side-effect-free movement into and out of the patient chamber, even at high magnetic field strengths.
Implementation Method 1
Since human beings are by and large diamagnetic, a location-dependent diamagnetic force is generated on the human body by this field distribution, which triggers the uncomfortable feelings in the patient.
Data Source
AI summary
A magnetic resonance device has a patient bed able to be automatically moved by means of a drive apparatus into a patient chamber, as well as a magnet arrangement for creating a magnetic field in the interior of the patient chamber. The drive apparatus is operated so as to move the patient bed at a speed determined as a function of the distribution of the magnetic field in the direction of movement of the patient bed.