Dynamic RF Power Control for MRI Patient Safety
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Solution Overview
Problem
Magnetic resonance examinations face challenges in accurately determining the distance between a patient and the enclosure surrounding the patient receiving area, which can lead to increased RF field amplitudes and potential RF burns, even when global SAR limits are observed.
Innovation Solution
A method that involves providing first size information of the patient before the examination, acquiring magnetic resonance data during the exam to determine second size information, and using this data to calculate the precise distance between the patient and the enclosure, thereby enabling precise determination and implementation of safety measures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RF power is restricted to prevent RF burns when patient is close to the enclosure, then patient safety is improved, but RF power transmission efficiency deteriorates
Solution Approach 1:
The patent implements dynamic adjustment of RF power transmission based on real-time patient position detection. The system continuously monitors the distance between the patient and the enclosure wall, and dynamically adjusts the RF power level accordingly - using high power when the patient is safely positioned and reducing power only when the patient approaches the wall, thus optimizing both safety and transmission efficiency throughout the examination
Solution Approach 2:
The system employs a feedback mechanism where the detected patient position information is fed back to the RF power control system. This feedback loop enables the system to automatically adjust RF power transmission levels based on the current patient-to-wall distance, ensuring safety constraints are met while maintaining optimal power transmission for image quality
2Reliability
If a minimum distance of 5 mm is prescribed from the enclosure, then patient safety is improved, but examination accessibility deteriorates
Solution Approach 1:
The patent replaces the static 5 mm minimum distance prescription with a dynamic safety mechanism. The system continuously monitors patient position and adjusts RF power transmission in real-time based on the actual distance to the enclosure wall. This allows patients of all body types to be examined safely without requiring a fixed minimum distance, thereby improving accessibility while maintaining safety
Solution Approach 2:
The system changes the safety approach from a fixed spatial parameter (5 mm minimum distance) to a dynamic power transmission parameter. By adjusting RF power levels based on real-time distance measurements, the system adapts safety constraints to each patient's anatomy and position, making examinations accessible to obese patients and others who would not meet a fixed distance requirement
3Reliability
If RF power is limited based on assumed close positioning, then patient safety is improved, but measurement precision deteriorates
Solution Approach 1:
The system performs preliminary detection of the patient's actual position relative to the enclosure wall before initiating or adjusting RF power transmission. This preliminary positioning information is used to determine the appropriate power level, ensuring both safety and optimal image quality from the start of the examination without requiring conservative power limiting assumptions
Solution Approach 2:
The system uses feedback from real-time patient position detection to continuously optimize RF power transmission levels. By monitoring the actual distance between the patient and the enclosure wall and adjusting power accordingly, the system maintains safety constraints while maximizing the RF power available for high-quality image acquisition
Data Source
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AI summary
The invention relates to a method for determining the distance of a patient to an enclosure surrounding a patient acquisition area of a magnetic resonance device during a magnetic resonance examination, comprising the following method steps: - providing first size information of the patient, wherein the first size information is provided before the start of the magnetic resonance examination, - acquiring magnetic resonance data of the patient during the magnetic resonance examination and determining second size information of the patient based on the acquired magnetic resonance data, and - determining the distance of the patient to the enclosure surrounding the patient acquisition area based on the first size information of the patient and based on the second size information of the patient.