Design of a neurosurgical manipulator for applications in MRI environment
This thesis presents the design of a personal computer (PC) based needle insertion robotic manipulator for biopsy. The robot was designed and built using materials available in the research laboratory. The robot is intended primarily for use inside the confined area of a cylindrical magnetic resonance (MR) scanner. Selection of the robot geometry and novel locations for drive actuators allowed placement of actuators outside the MRI bore. The robot is modeled using Denavit-Hartenberg transformations. Custom developed software control is developed to test the functional aspects of the robot. The robot performs to the tolerance required for the stated clinical application. This thesis addresses only proof of concept chosen for the manipulator design and is not ready for any clinical trials. The work also addresses MRI compatible and safety issues and recommends appropriate materials for future development. Traditionally, neurosurgical navigation has relied on preoperative images and the assumption that anatomical structures of interest remain in the same position with respect to each other and the fiducial markers used for registration. However, during surgery, tissue deformation and shift disrupt the spatial relation between the patient and the preoperative image volumes. This results in localization errors. Developing a manipulator that works inside an imaging machine guided by real time images is expected to minimize the problem of “tissue shift” during the surgery.
Robotics, MRI environment, Neurosurgical manipulator