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Abstract
Magnetic Resonance Imaging (MRI) is widely used in medical procedures and supporting research due to its ability to view interior anatomical structures inside living systems, providing high-quality soft tissue imaging while not exposing patients or subjects to ionizing radiation or contrast agents. Advances in MRI technology have led to the development of numerous MR-guided therapies which exploit the excellent soft tissue contrast and high spatial resolution of MRI. This development of hardware and software in the realm of MRI-guided interventions has provided a framework on which the creation of new systems for MRI-guided targeting systems can be built.Working inside the MR environment imposes several limitations on materials and procedures used. Given the tremendous magnetic field present, safety concerns dictate that only certain materials may be used, restricting choices for structural, actuation, and encoding materials. Beyond safety concerns, other materials and electronic signals become undesirable by causing interference with MR image acquisition. The limited space of the bore limits access to subjects and imposes limitations on the size of systems designed for intrabore use. Successful mitigation of all these factors is necessary when developing successful designs for MR-guided therapies.The core of this dissertation is built around three projects: 1) a sample positioning platform for high-field, small-bore MRI; 2) a needle and catheter guidance robot for prostate cancer treatment; and 3) a needle guidance system for stem cell injections into the spines of minipigs. The prostate robot, developed for the NIH Center for Cancer Research, is designed as a guide for needle insertions to a target tumor, after which a laser catheter is inserted to ablate the diseased tissue. The robotic needle guide provides continuous coverage of the prostate and aims to allow surgeons perform MR-guided ablations more quickly. Development of the spinal targeting system for minimally invasive stem cell injection into the spinal cord is part of a larger study to explore ALS therapies, for which a fixed-motor two-axis rotation stage was developed. These projects, while differing in application and final design, are linked through their use of pneumatic motors and overall design criteria.