Robotic Needle-based Intra-cavitary Surgery (InCavBot)

Abstract

Intra-cavitary needle-based interventions are challenging due to highly deformable cavity and targeted tissue motions. Multi-needle insertions are more challenging given the continuously shifting boundary conditions of surrounding structures intra-operatively. This thesis presents the furtherment of enabling technologies for surgeries seeking to enhance treatment effectiveness by improving needle insertion performance. A modular phantom-based insertion platform was designed and implemented as a framework for comparative studies. The main elements of this platform -- organ phantom, needle guidance unit, and needle driving unit -- were defined for intra-cavitary brachytherapy in cancer treatment with potential for other investigations. The platform performance was conducted through force/torque and electromagnetic data acquisitions. A novel needle driver was devised combining simultaneous translational and rotational oscillations at needle base to investigate optimum needle motion within intra-cavitary limitations having the minimized needle-tissue interaction while maintaining needle mechanical properties for non-straight needle guides. Optimal hybrid oscillational needle motion through in-vitro experiments were concluded to achieve a desirable velocity-independent force profile. A force model encompassing combined oscillations was developed to estimate axial needle force. A multi-stage insertion methodology was elaborated to characterize the interaction between needle and guide within needle-tissue interaction. The intra-operative frictional controllability (IFC) index is proposed for insertion performance management using the frictional power rate of the needle through its guide at different insertion velocities, since velocity changes are inevitable. IFC provides effective criterion to surgeons for optimal needle management specifying power change requirements during velocity-sensitive needle guide frictional reactions. Minimizing the range of frictional power changes, intra-operatively, increases control over the insertion process. IFC was calculated for two needle guides using the implemented platform. A multi-needle-insertion-based intra-cavitary robotic system (InCavBot) resulted from preliminary evaluation and design factors accounting for all requirements and constraints. Kinematic and workspace analyses were conducted for the candidate system that incorporates two serial manipulators. A volumetric index was introduced to prioritize the needle insertion order, based on changes in the targeting workspace after each insertion. Design concepts and prototypes were presented for a proactive intra-cavitary needle guide with organ immobilizing options, a hybrid oscillational needle driving hand tool, and an intra-cavitary needle anchorage unit.