Improved FBG-Based Shape Sensing Methods for Vascular Catheterization Treatment

Fiber optic shape sensing is gaining popularity within areas such as medical catheterization where catheters and guidewires are used to navigate through tortuous vascular paths. Shape sensing can aid medical interventionalists by reducing exposure to damaging radiation and providing a more detailed real-time understanding of the 3-dimensional shape of the catheter/guidewire. However, despite the technology existing for several years, there is still room for improvement and steps to follow to reach the accuracy and robustness needed for these safety-critical applications. This letter discusses and provides methods for fiber integration within catheters to improve shape estimation accuracy and repeatability. A two-step calibration process is introduced for intrinsic twist compensation, which results in significant improvements in estimation accuracy. Additionally, a practical method for fiber parameter identification is introduced. The importance of estimating these parameters was found to be paramount for reaching adequate shape estimation. Further improvements to the reconstruction algorithm are proposed. Experimental validations with ground truth shapes are performed to assess the overall accuracy for static and dynamic configurations. For complex geometrical shapes and a fiber length of 170 mm, experiments show a mean spatial error of 0.70 mm (0.41\%), a maximum of 2.52 mm (1.48\%), and repeatability of \pm 0.82 mm.