Accuracy of needle position measurements using fiber Bragg gratings

Abstract

Accurate placement of the needle tip is essential in percutaneous therapies such as radiofrequency ablation (RFA) of liver tumors. Use of a robotic system for navigating the needle could improve the targeting accuracy. Real-time information on the needle tip position is needed, since a needle deflects during insertion in tissue. Needle shape can be reconstructed based on strain measurements within the needle. In the current experiment we determined the accuracy with which the needle tip position can be derived from strain measurements using Fiber Bragg Gratings (FBGs). Three glass fibers equipped with two FBGs each were incorporated in a needle. The needle was clamped at one end and deformed by applying static radial displacements at one or two locations. The FBG output was used for offline estimation of the needle shape and tip position. During deflections of the needle tip up to 12.5 mm, the tip position was estimated with a mean accuracy of 0.89 mm (std 0.42 mm). Adding a second deflection resulted in an error of 1.32 mm (std 0.48 mm). This accuracy is appropriate for applications such as RFA of liver tumors. The results further show that the accuracy can be improved by optimizing the placement of FBGs.

Design of an actively controlled steerable needle with tendon actuation and FBG-based shape sensing

“…To assess the error build-up of a steering task, some form of trajectory error [19] or end-point error [16,20] is generally reported. For this, position information is acquired by various sensors, such as cameras [21,22], electromagnetic sensors [12], ultrasound probes [23], fluoroscopic X-ray [24], and fiber Bragg gratings (FBGs) [25][26][27].…”

Shape reconstruction for wire-driven flexible robots based on Bézier curve and electromagnetic positioning

“…Medical image based methods are often used, such as Ultrasound [19] and Magnetic Resonance Imaging (MRI) [20]. Another popular technology that has been well studied is the Fiber Bragg Grating (FBG) [21,22] based method. In addition, the Electromagnetic Tracking (EMT) [23] is also studied to detected the bending characteristics of a multi-segment continuum robot in contact with the environment.…”

Enhancement of accuracy in shape sensing of surgical needles using optical frequency domain reflectometry in optical fibers

“…Characterization of the fibers triplets' geometry along the entire sensor fiber is therefore crucial to achieving precise measurements. A characterization method proposed by Roesthuis et al [20] was implemented to evaluate the relative position between the fibers over the entire lengths of the fibers in the triplet. The idea of this technic is to bend the needle in a predictable shape by fixing its basis axis and moving the tip by a known distance.…”

“…To reach this precision, three fibers were used, each containing 2 FBGs separated by 63mm each inside a 15cm long needle. A precision of 0.74 -1.2 mm [2, 14,18,20] were obtained using different needles length and different numbers of FBG sensors spaced out at various distances along the fibers. However, shape tracking of the entire device can be of clinical value especially during vascular interventions for catheter tracking.…”

“…To do so, FBGs are used to sense the strain locally, which is directly related to the curvature radius of the fiber. To orientate the curvature radius in the laboratory frame, at least three fibers are used glued in a particular geometry (linear [15,16], triangular [12,17,18] or square [19] cross-section) in order to get two or three degrees of freedom. A simplified design implying a multicore fiber has been proposed and demonstrated accurate results [1].…”