MRI Head Position Detection for Accurate SAR Limit Checking
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Solution Overview
Problem
Existing magnetic resonance imaging (MRI) systems lack precise methods to determine the position of a patient's head during examinations, particularly in feet-first positions, leading to inaccurate estimation of specific absorption rate (SAR) values and potential overheating risks.
Innovation Solution
A method using distance and object measurement sensors to accurately determine the position of a patient's head, employing a lookup table to calculate SAR values, and a machine learning model for verification, ensuring adherence to safety limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a rough estimation method is used to assume the head is always in the isocenter, then the examination can proceed without complex positioning systems, but the SAR values may be inaccurately calculated leading to potential safety issues
Solution Approach 1:
The patent replaces mechanical positioning systems with optical sensors (camera systems) to detect head position. The camera captures images of the patient's head and uses image processing algorithms to determine precise position coordinates, eliminating the need for complex mechanical positioning apparatus while achieving accurate SAR calculation.
Solution Approach 2:
The patent introduces an intermediary computational model that maps camera image coordinates to the MRI scanner's coordinate system. This intermediary transformation layer enables accurate head position determination in the scanner's reference frame, allowing precise SAR calculation without direct mechanical measurement in the scanner coordinate system.
2Reliability
If precise head position determination is implemented using sensors and computational models, then SAR values can be accurately calculated, but the system complexity and cost increase
Solution Approach 1:
The patent uses optical copying by capturing images of the patient's head with a camera system. Instead of directly measuring position with complex sensors in the MRI coordinate system, the system creates an optical copy (image) of the head and processes this copy to determine position, significantly simplifying the measurement apparatus.
Solution Approach 2:
The patent makes the camera system serve multiple functions: it captures patient positioning information for SAR calculation, verifies head presence in the field of view, and can potentially be used for other imaging or monitoring purposes. This multi-functionality reduces the need for separate dedicated positioning sensors.
3Ease of operation
If the head coil is used to mechanically define head position, then positioning is simplified for head-first examinations, but the system cannot accommodate feet-first positions with the same accuracy
Solution Approach 1:
The patent enables the system to automatically determine head position and calculate SAR values without requiring manual intervention or different positioning methods for different examination types. The camera system autonomously captures head position, and the computational model automatically adapts to calculate accurate SAR values regardless of whether the patient is in head-first or feet-first position.
Data Source
AI summary
One or more example embodiments relates to a method for position determination during a magnetic resonance examination and checking a medical limit value. The method comprises determining position information of a specific part of a body of a patient on a patient table; and checking the magnetic resonance sequence for adherence to the at least one limit value using the position information of the specific part of the body. One or more example embodiments makes possible a specific determination of the absorption rate of specific parts of the body and an increase in the performance of a magnetic resonance apparatus.