MR-conditional Concentric Tube Robots in Neurosurgical Applications
This dissertation presents the design, manufacturing, control, and validation of actuation systems and robotic platforms to deploy the concentric tube robot under magnetic resonance image (MRI) guidance for neurosurgical applications. The motivation for MR-guided concentric tube robot based neurosurgical interventions comes from (1) the high-resolution image quality of soft tissue, no radiation exposure, and accurate thermal does monitoring capability provided by MRI, (2) the large number of patient who could benefit from the proposed robotic platforms ( intracerebral hemorrhage accounts for 10% to 15% of all the strokes with the 30-day mortality rate of about 43%; epilepsy is a prevalent neurological disorder which affects 65 million people in the world), and (3) limited treatment outcome and the invasive characteristics of the existing approaches to treat the neurosurgical disorders. However, the challenges in developing an MR-conditional robot are clear: the confined in-bore space of MRI scanners induces spatial constraints and strong magnetic field precludes the use of conventional medical devices made of ferromagnetic or paramagnetic materials. Therefore, the goal of this work presented here is to (1) develop an MR-conditional pneumatic actuation unit and (2) apply it to construct the concentric tube robot for the intracerebral hemorrhage and epilepsy applications. The design, fabrication, working principle, encoding, control, and validation of the actuation unit are described. This motor has the advantages of 1) simple continuous actuation, 2) compact optical encoding, 3) low-cost additive manufacturability, and 4) ability to integrate with off-the-shelf modular gearboxes to meet various requirements. Having this robust MR-conditional actuation unit, two different types of MR-guided concentric tube robots are developed to treat the intracerebral hemorrhage and epilepsy respectively. Real-time MR imaging is integrated into the intracerebral hemorrhage evacuation robot control loop to provide the accurate manipulation of the concentric tube and intraoperative monitoring the treatment outcome. In the epilepsy treatment, a novel helical shape concentric tube robot with RF ablation capability is presented to enable minimally invasive, transforamen ovale approach under MR image guidance. Both robots are tested in phantom models and ex vivo tissue within a 3T MRI scanner to validate their performances, i.e. MR-conditionality, in-scanner targeting performance, image-guided hemorrhage evacuation, and MR-guided ablation respectively. This dissertation herein addresses the design, modeling, control, and experimental validation of MR-conditional concentric tube robots with particular interest to neurosurgical applications. The hardware components and control methods could potentially pave the way for the MR-guided minimally-invasive approach to treat the neurological disorders in the future.