Date of Award
Department or Program
Paul M. Meaney
Keith D. Paulsen
Laura E. Ray
This project seeks to develop an updated version of a microwave imaging device for use in conjunction with breast MRI, improving upon existing technology and developing novel concepts for the device. It posits three primary redesign targets for updating the previous system: resizing the system height, making the device more iteration- friendly, and improving the overall manufacturability of the device by replacing custom components with commercially available alternatives. All three of these redesign targets are met in the new design, V2.0. The height is reduced by reducing antenna travel and height, embedding some components, and shortening the tank wall, resulting in 4.65 cm of height savings from the previous version. The hand-machined acrylic plates are replaced by laminated, laser cut acrylic pieces to increase ease of prototyping, meeting the second target. The worm, worm wheel, lead screw, and lead nut are replaced with commercial components to improve manufacturability.
To develop the novel components, extensive torque testing is performed to quantify the system torque requirements, yielding a maximum torque expectation of 0.6 N-m. A pneumatic motor is selected with a minimum torque rating of 2 N-m for rated pressure, meeting the minimum safety factor of 2 for the torque specification. A carbon fiber drive shaft and support mechanism are designed to ensure patient safety around the motor and prevent degradation of the images while in the MRI suite. Finally, a patient bed design is presented to house the device, shield the motor, and provide a platform for the patient to lie on.
Preliminary testing results indicate that all the redesign targets are met and demonstrate that the gearing system is more robust and that the novel components all have merit for further development and exploration. Ex situ mechanical testing provides a verification that the components are functioning as expected and provides a way to tune the controller outside of the MRI suite. The next step for the project is to perform a phantom trial to ensure that the mechanical system functions in situ as expected, and pending a successful result, moving to a clinical trial with volunteer patients.
Player, Grace M., "Mechanical Design of a Microwave Imaging Device for Breast Cancer Detection in MRI Scanners" (2023). Dartmouth College Master’s Theses. 116.
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