Modeling and steering of a novel actuated-tip needle through a soft-tissue simulant using Fiber Bragg Grating sensors

Abstract

Needle insertions are common during surgical procedures. Accurately delivering the needle at a specific location in the human body is of importance for the clinical outcome of the procedure. Studies have already shown that robotically inserting traditional needles with a bevel tip can improve targeting accuracy. However, steering of such needles requires spinning the needle, which may lead to additional tissue damage. Therefore, we propose a novel design consisting of a flexible needle with a tendon-driven actuated-tip. Changing the orientation of the actuated-tip allows to control the steering direction of the needle and the amount of deflection. We derive the kinematic model which describes the needle path given the actuated-tip orientation based on nonholonomic kinematics. We present a method for steering the needle towards a target location in soft tissue. This method incorporates online parameter estimation in order to adapt for changes in tissue stiffness. Needle insertion experiments are performed in softtissue simulants, made from porcine gelatin. Needle tip pose is measured during insertion using Fiber Bragg Grating (FBG) based shape reconstruction. Results show that the needle can be steered towards targets located at 20 mm from the initial insertion axis, at a depth of 100 mm with a mean targeting error of 2.02 mm.

Steering an actuated-tip needle in biological tissue: Fusing FBG-sensor data and ultrasound images

“…For further details regarding shape reconstruction, we refer the reader to our previous study [20]. Steering of an actuated-tip needle using the reconstructed shape from FBG sensors towards virtual targets was performed in previous work [9], [10]. In this work, the reconstructed shape from FBG measurements is combined with ultrasound-based needle tracking to enable steering towards real targets.…”

“…The actuated tip needle consists of a conical tip, mounted on a ball joint [9], [10]. A set of four tendons are routed through the shaft of the needle and are attached to the conical tip, which enables changing of the actuated-tip orientation.…”

“…Active needles can change their shape, either at the tip or along the entire length. Examples of active needles are concentric tubes [5], [6], pre-curved stylet [7], programmable bevel [8] and tendon-actuated tip [9], [10] needles. Passive needles need to be rotated along their longitudinal axis in order to control their path through the soft tissue.…”

“…On the other hand, active needles can be steered in any direction without rotating the needle along its longitudinal axis. In our previous work, we presented a novel actuated-tip needle and developed a model and a controller to steer the needle [9]. Fiber Bragg Grating (FBG) sensors were used to reconstruct the needle shape.…”

Endpoint Accuracy in Manual Control of a Steerable Needle

“…Tip-articulated needles do not require axial rotations for steering. They allow for both robotic (20,21) and manual approaches (6).…”