Design and testing of an MR-conditional six-degree-of-freedom phantom robot


Motion phantoms can help accelerate and reduce the associated costs of research focused on motion-robust imaging. Currently available phantom robots for magnetic resonance imaging (MRI) lack sufficient degrees of freedom (DOF) to replicate complex physiological motions. This work presents the design and testing of a six-DOF MRI-conditional phantom robot to simulate such motions. 
Approach:
The system was fabricated predominantly with 3D printed components as well as DC stepper motors. Testing validated the actuator's functionality and conditionality with a 3T MRI system. A Faraday cage to house the motors and electronics was constructed using a conductive coating on a 3D-printed shell. 
Main Results:
The Faraday cage was found to reduce the noise power produced by the motors to the baseline level measured in the MRI without the robot being present within the MRI suite. A positional accuracy measured using a modified version of ISO 9283 was found to be 0.2mm and a rotational accuracy of [-0.1°, 0.3°, -0.2°] were measured for the x, y, and z directions, respectively. Path accuracy for sample motions was found to have a positional accuracy of 0.3 mm and rotational accuracy of [0.1°, 0.1°, 0.1°].
Significance:
The created six-DOF robot enhances the development and validation of motion-robust imaging in MRI. The presented design is covered by WO patent #2023/184043, 2023/09/28.&#xD.