Preoperative Motion Planner for Steerable Needles Using Cost Map Based on Repulsive Field and Empirical Model of Needle Deflection

Needle insertion is a common procedure in percutaneous puncture. A motion planner for a steerable needle that considers the risk level of the path in anatomical environment and the actual deflection of clinical needle is necessary. A novel preoperative motion planner for a steerable needle controlled by robot is proposed. Our method utilizes sampling-based planner to compute candidate path in the reachable region, the path solutions are optimized by calculating the cost of a path based on a cost map. The cost-map, which is built based on repulsive field theory from CT image, encodes the information of the obstacle locations and the criticality of the anatomical environment. The empirical formula that can predict needle trajectory is obtained by insertion experiments. Experiments shown that positioning error in gelatin phantom under the guidance of our planner is less than 1.1mm. Comparing with the straight-line insertion method, the positioning error was reduced by 80%. The results indicate that the motion planner has the potential to provide effective guidance for robot-assisted puncture surgery while enhancing the position precision and patient safety.

Steerable Needle Trajectory Following in the Lung: Torsional Deadband Compensation and Full Pose Estimation With 5DOF Feedback for Needles Passing Through Flexible Endoscopes

Bronchoscopic diagnosis and intervention in the lung is a new frontier for steerable needles, where they have the potential to enable minimally invasive, accurate access to small nodules that cannot be reliably accessed today. However, the curved, flexible bronchoscope requires a much longer needle than prior work has considered, with complex interactions between the needle and bronchoscope channel, introducing new challenges in steerable needle control. In particular, friction between the working channel and needle causes torsional windup along the bronchoscope, the effects of which cannot be directly measured at the tip of thin needles embedded with 5 degree-of-freedom magnetic tracking coils. To compensate for these effects, we propose a new torsional deadband-aware Extended Kalman Filter to estimate the full needle tip pose including the axial angle, which defines its steering direction. We use the Kalman Filter estimates with an established sliding mode controller to steer along desired trajectories in lung tissue. We demonstrate that this simple torsional deadband model is sufficient to account for the complex interactions between the needle and endoscope channel for control purposes. We measure mean final targeting error of 1.36 mm in phantom tissue and 1.84 mm in ex-vivo porcine lung, with mean trajectory following error of 1.28 mm and 1.10 mm, respectively.

A Curved Port Delivery System for Laser Interstitial Thermal Therapy of Brain Tumors

Laser interstitial thermal therapy (LITT) is a neurosurgical procedure that involves using heat treatment to ablate glioblastomas in the brain. Current methods for placing probes in LITT involve straight trajectory pathways. This limitation often requires surgeons to make multiple trajectories or leave undesired margins. There has been extensive work in steerable needles, concentric tube cannulas, and flexible surgical tools. In this work, we present an approach which focuses on providing steerability to tools that aren’t inherently steerable. To do this, we developed a curved port delivery system that leverages an active cannula for the deployment of a plastic, flexible port that delivers existing surgical tools. We present an initial prototype coupled with feasibility results illustrating that the port can be placed to steer probes to a desired location.