Design and analysis of a fiber-optic sensing system for shape reconstruction of a minimally invasive surgical needle

Aizhan Issatayeva,Wilfried Blanc,Daniele Tosi,Aida Amantayeva,Carlo Molardi

doi:10.1038/s41598-021-88117-7

Abstract

This paper presents the performance analysis of the system for real-time reconstruction of the shape of the rigid medical needle used for minimally invasive surgeries. The system is based on four optical fibers glued along the needle at 90 degrees from each other to measure distributed strain along the needle from four different sides. The distributed measurement is achieved by the interrogator which detects the light scattered from each section of the fiber connected to it and calculates the strain exposed to the fiber from the spectral shift of that backscattered light. This working principle has a limitation of discriminating only a single fiber because of the overlap of backscattering light from several fibers. In order to use four sensing fibers, the Scattering-Level Multiplexing (SLMux) methodology is applied. SLMux is based on fibers with different scattering levels: standard single-mode fibers (SMF) and MgO-nanoparticles doped fibers with a 35–40 dB higher scattering power. Doped fibers are used as sensing fibers and SMFs are used to spatially separate one sensing fiber from another by selecting appropriate lengths of SMFs. The system with four fibers allows obtaining two pairs of opposite fibers used to reconstruct the needle shape along two perpendicular axes. The performance analysis is conducted by moving the needle tip from 0 to 1 cm by 0.1 cm to four main directions (corresponding to the locations of fibers) and to four intermediate directions (between neighboring fibers). The system accuracy for small bending (0.1–0.5 cm) is 90% and for large bending (0.6–1 cm) is approximately 92%.

Highlights

This paper presents the performance analysis of the system for real-time reconstruction of the shape of the rigid medical needle used for minimally invasive surgeries
Image-guided techniques include fluoroscopy, computer tomography (CT), magnetic resonance imaging (MRI), and ultrasound. Fluoroscopy[12,13] and CT14 give satisfactory image-guidance during Minimally invasive surgery (MIS), they are accompanied by the exposure of the physicians and patients to ionizing radiation[12,15]
The strain detected by the right-left pair is different from the strain pattern of upper-lower fibers: first of all, it is much smaller and secondly, the two opposite fibers experience the strain with the same sign

Summary

Introduction

This paper presents the performance analysis of the system for real-time reconstruction of the shape of the rigid medical needle used for minimally invasive surgeries. Most MIS procedures involves the insertion of the needles, minimally invasive applicators, endoscopes, and catheters inside the human body. The examples of such surgeries include biopsy, b rachytherapy[4], drug and anesthetic delivery (i.e. epidural a nesthesia5,6), percutaneous robotics surgeries[7,8], cancer treatment by thermal a blation[9], endoscopic s urgeries[10] and others. Undesired EM fields, as well as interference from metal or ferromagnetic sources around the system, can result in a diminishing of measurement a ccuracy[3] Another promising method for MIS guidance is shape sensing of the needle based on the fiber optic sensors. Battisti et al.[20] mention that in comparison with MRI guidance the rate of the update was higher by 100 ms and the latency was lower by 300 ms

Methods

Results

Discussion

Conclusion