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

Abstract

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.

Autonomous medical needle steering in vivo

“…( 49 ) and extended by Ertop et al. ( 27 ). We adapted those methods by breaking the trajectory up into a series of insertions with a predetermined 10-mm arclength.…”

“…Prior work by us and others has demonstrated ex vivo needle steering in lung tissue, as well as other organs ( 1 , 3 , 26 , 27 ). These experiments are important for characterizing the properties and capabilities of the devices but are insufficient to indicate clinical feasibility.…”

“…We adapted those methods by breaking the trajectory up into a series of insertions with a predetermined 10-mm arclength. At the end of each segment of insertion, the controller corrected the rotational angle by reorienting the needle tip [using an extended Kalman filter ( 27 )] to minimize the angular error with respect to the planned trajectory. Each of these insertion segments took about 4 s. In the in vivo experiments, one insertion segment was performed during each safe insertion time window, and the controller was then paused between the safe insertion time windows during normal breathing.…”

“…A 5-DOF tracking coil was embedded within the needle at its distal tip. The robot autonomously deployed the needle along a planned trajectory under closed-loop control to the target while avoiding obstacles (12,27). The robot steered the needle autonomously to overcome the known challenges of manual deployment of steerable needles (8,9).…”

“…Then, the system controlled the needle along the planned trajectory, steering safely and accurately until the needle reached the target. To steer the needle along the planned trajectory, we adapted the controller originally presented by Rucker et al (49) and extended by Ertop et al (27). We adapted those methods by breaking the trajectory up into a series of insertions with a predetermined 10-mm arclength.…”