Abstract: PD42-12
Sources of Funding: None

Introduction

To address limitations of current commercial, mass-produced robot-assisted surgical systems widely used in urology and other surgical specialties, we propose to develop patient- and procedure-specific dexterous robots. Our focus is on a class of continuum robots known as concentric tube robots, which are comprised of a series of hollow, nesting, precurved tubes that are individually inserted and rotated with respect to one another in order to change the shape of the overall robot. We aim to develop a method for designing, fabricating, and driving a patient-specific concentric tube robot as an alternative paradigm to traditional robotic surgical systems in order to improve procedures for specialized patient groups. As a test case we focus here on nonlinear renal access, for example, subcostal punctures into the upper pole calyces of the kidney to ablate an endophytic renal mass.

Methods

To enable patient-specific design of these robots, a virtual-reality based interface was developed. The interface leverages the expertise of a surgeon by immersing him or her in a 3-D virtual environment that includes a reconstructed model of the patient’s thoracoabdominal anatomy based on CT scans. Once the surgeon designs the set of concentric tubes, we generate a 3-D model and subsequently 3-D print each tube using a biocompatible polycaprolactone (PCL) filament. The printed tubes are then nested one inside the next and attached to the compact, modular actuation and control system we built for driving these robots. The surgeon controls the movement of the concentric tube robot through a teleoperation control scheme.

Results

A board-certified urologist performed a preliminary test of the entire system. After an explanation of the interface and its features, the surgeon was immersed in the virtual environment (using 3D reconstructions of an actual patient's upper abdominal anatomy, including kidney and an associated upper caliceal lesion) and tasked with designing a set of tubes to access the lesion. Based on his intuition and expertise, he designed three different sets, which were then 3-D printed with PCL. The surgeon then performed mock procedures by driving each concentric tube robot into a phantom model of the patient's thoracoabdominal anatomy in order to reach the lesion. The lesion was generated using a thermochromic dye which changes color when heated. Once the target was reached, a radiofrequency ablation (RFA) probe was passed through the concentric tube robot and successful ablation confirmed by color change of the lesion.

Conclusions

This work proposes a framework for integration of the surgeon into design and fabrication of a set of patient- and procedure- specific concentric tubes. Preliminary results demonstrate that a surgeon can use the interface to design a concentric tube robot to access and ablate renal lesions by RFA.

Funding

None