Two-dof non-metal manipulator with pneumatic stepping actuators for needle puncturing inside open-type MRI

The magnetic resonance imaging (MRI) system is useful in intraoperative surgical treatment. Many manipulators for the clinical application on an MRI bed are reported. In many cases, piezoceramic motors have been used for these manipulators. However, a piezoceramic motor produces an electromagnetic wave that influences an MRI image. In this paper, we develop an MRI-safe pneumatic stepping actuator and an MRI-safe needle guiding manipulator. This actuator and the manipulator are made of only resin. In addition, this pneumatic stepping actuator can be operated at a distance of 8 [m] from the compressor. By using these devices, we construct an MRI-safe system in which there are no metallic or electronic parts inside the MRI room. From the result of the accuracy evaluation experiment, it is evident that this manipulator inserts the needle at the high accuracy. Further, we confirm that this system has a high magnetic resonance (MR) compatibility.