Strain Sensor Securing Strap for MRI Patient Motion Detection
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Solution Overview
Problem
Current methods for detecting patient movement during medical imaging, such as magnetic resonance imaging, are either invasive, require significant operational changes, or are ineffective in detecting movements outside the active receive coil field.
Innovation Solution
A measuring arrangement that uses strain sensors integrated into securing straps fastened to the patient table, which detect tensile forces caused by patient movement, allowing for precise measurement and quantification of patient motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical transducers (respiratory belts) are used to detect patient movement, then patient motion can be detected, but patient comfort deteriorates and workflow becomes overloaded
Solution Approach 1:
The patient table itself serves as the sensing element by integrating strain sensors directly into its structure. The table automatically detects patient movements through strain changes without requiring external attachments or manual setup by staff, thus maintaining reliable motion detection while eliminating the workflow burden of attaching and configuring separate mechanical transducers
Solution Approach 2:
The patient table is designed to perform multiple functions: it provides patient support during imaging while simultaneously serving as the sensing platform for motion detection through integrated strain sensors. This eliminates the need for separate dedicated motion detection devices and their associated setup procedures
2Ease of operation
If video cameras are used to monitor patient movement remotely, then non-contact detection is achieved, but detection reliability deteriorates when direct line of sight is obstructed
Solution Approach 1:
The optical/mechanical video camera system is replaced with an electrical sensing system based on strain sensors integrated into the patient table. This substitution maintains non-contact detection (no physical attachment to patient) while eliminating line-of-sight obstructions, as the strain sensors detect movements through electrical signal changes in the table structure itself
3Reliability
If pilot tone transmitters and receive coils are used to detect patient movement, then motion can be detected during MRI, but device complexity increases and external interference affects reliability
Solution Approach 1:
The complex pilot tone transmission and reception system with multiple coils and frequency tuning mechanisms is extracted and replaced with a simplified strain sensor system. The patient table structure itself becomes the sensing element, eliminating the need for separate transmitters, receive coils, and associated control software modifications
Solution Approach 2:
The strain sensors act as an intermediary between the patient table structure and the control device, converting mechanical strain from patient movements into electrical signals that can be processed. This intermediary approach simplifies the overall system compared to direct electromagnetic field interaction methods
4Reliability
If magnetic field sensors (Hall sensors) are incorporated in local coil arrays to detect patient movement, then motion detection is achieved, but detection precision deteriorates when sensors move in parallel without angle change
Solution Approach 1:
Instead of using magnetic field sensors that detect changes in magnetic field orientation (which fail when movement is parallel to the field), the approach is inverted by using strain sensors that directly measure mechanical deformation of the patient table. This inversion of the sensing principle ensures detection of all movement types, including parallel movements, by measuring the physical strain caused by patient motion on the table structure
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 solution provides a non-invasive, efficient, and cost-effective means to detect and quantify patient movement, enabling improved image quality by allowing for motion correction and compensation during medical imaging procedures.
Implementation Method 1
at least one strain sensor, in particular, for detecting tensile forces introduced into the at least one securing strap by movements of the patient
Data Source
AI summary
A measuring arrangement for measuring movements of a patient positioned recumbently on a patient table includes the patient table and a securing strap for locally securing the patient on the patient table. The securing strap is flexible and has at least one first fastener that co-operates with a second fastener of the patient table for fastening the securing strap. The measuring arrangement includes a strain sensor provided as part of the securing strap and/or motion-coupled thereto, and a control device for determining motion information describing the movements of the patient from sensor data of the strain sensor.