Three-Dimensional Needle Shape Reconstruction Using an Array of Fiber Bragg Grating Sensors

Abstract

We present a prototype of a flexible nitinol needle (φ 1.0 mm and length 172 mm) integrated with an array of 12 Fiber Bragg Grating (FBG) sensors. These sensors measure the axial strain, which enables the computation of the needle curvature. We reconstruct the three-dimensional (3-D) needle shape from the curvature. Experiments are performed where the needle is deflected in free space. The maximum errors between the experiments and beam theory-based model are 0.20 mm (in-plane deflection with single bend), 0.51 mm (in-plane deflection with double bend), and 1.66 mm (out-of-plane). We also describe kinematics-based and mechanics-based models for predicting the 3-D needle shape during insertion into soft tissue. We perform experiments where the needle is inserted into a soft-tissue simulant, and the 3-D needle shape is reconstructed using the FBG sensors. We compare the reconstructed needle shape to deflection obtained from camera images and our models. The maximum error between the experiments and the camera images is 0.74 mm. The maximum errors between the kinematics-based and mechanics-based models and the camera images are 3.77 mm and 2.20 mm, respectively. This study demonstrates that deflection models and needles integrated with FBG sensors have the potential to be used in combination with clinical imaging modalities in order to enable accurate needle steering.

Force sensing in continuum manipulators using fiber Bragg grating sensors

“…The FBG sensors have been used for reconstruction of needle shape during insertion into soft-tissue phantoms, and for shape reconstruction of a tendon-driven continuum manipulator in free-space [18], [19]. Strain measurements from at least 3 co-located FBG sensors are required in order to calculate the magnitude ( κ ) and direction (ϕ) of the curvature vector at a specific location (s k , k ∈ Z + ) along the manipulator shaft ( Figure 2).…”

“…Substituting (17) and (18) into (19) leads to the estimate of the external force F ext that is given below:…”

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

“…To do so, an optical backscatter reflectometer was used for strain measurements. Then, the geometrical model suggested by [24] combined with the approach suggested by [14] were used to obtain fiber triplets characteristics leading to shape tracking based on strain measurements. Measurements on three different types of fiber triplets (SMF-28, Hydrogen-loaded Germanium-Boron doped fibers (Redfern) and Hydrogen-loaded UV exposed SMF-28 (UVE-SMF-28)) were performed in order to correlate the attainable accuracy with the scatter level in the fibers.…”

“…Medical robotics for image guided prostate biopsies has also used shape sensing to track needle deflections during insertions [14]. To do so, FBGs are used to sense the strain locally, which is directly related to the curvature radius of the fiber.…”

“…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.…”