Robotic needle steering [electronic resource] : design and evaluation for clinical application
Keywords: Mechanical Engineering.

Robotic needle steering is a promising technique to improve the effectiveness of needle- based clinical procedures by computer-controlled, curved insertions of needles within solid organs. The concept of needle steering is based on the observation that long, thin flexible needles with tip asymmetry will curve during insertion within tissue. By exploiting this behavior, steerable needles can be redirected within tissue to reach targets that would be unreachable with traditional straight needles. The goal of this dissertation is to develop an integrated needle steering system with a user interface, capable of operating within the constraints of clinical environments. This thesis focuses on the design, implementation, and experimental validation of a robotic needle steering system that addresses three key challenges related to clinical needle steering. The first topic of this thesis is the characterization of needle steering in ex vivo and in vivo biological tissue. The effects of a variety of needle and insertion parameters (including needle geometry and insertion velocity) on needle behavior were evaluated in ex vivo biological tissue under fluoroscopic imaging. The first robotic needle steering experiments in living tissue were also conducted to explore how needle behavior changes in vivo. Additionally, potential clinical applications of robotic needle steering for biopsy, brachytherapy, and ablation are presented, through the use of standard clinical tools in conjunction with steerable needles. An important component of needle steering is the ability to control needle curva- ture during insertion. This has previously been done via duty-cycled spinning control. The second topic of this thesis is the development, modeling, and experimental eval- uation of two new methods for duty-cycled control of steerable needle curvature that do not require continuous needle spin are presented. These methods enable the use of sensors such as electromagnetic trackers and force/torque sensors with steerable needles, which are important for implementation of teleoperated needle steering. The third topic of this dissertation is the development of an intuitive teleoperation control scheme for a human operator. Needles that steer by needle-tip asymmetry are nonholonomic systems, which are difficult for humans to control manually due to under-actuation and unintuitive kinematic constraints. A new teleoperation approach for nonholonomic systems (steerable needles in particular) is presented. This algorithm allows a user to command the desired position of a robot in Cartesian space and provides force feedback to represent kinematic constraints and the position error of the robot. A user study with a virtual needle steering environment was conducted to evaluate the effectiveness of Cartesian-space teleoperation in a steerable needle targeting task in comparison to traditional joint space teleoperation. Cartesian-space teleoperation significantly improves performance metrics, including time-to-target, overall needle insertion length, and targeting error. We implemented an integrated teleoperated robotically-driven steerable needle and virtual reality environment, relevant to clinical scenarios. The integrated system was evaluated in an animal cadaver using Cartesian space teleoperation, under live fluoroscopic imaging. The work in this thesis enables future clinical application of robotic needle steering, as well as patient-specific pre-operative needle steering training simulators.