Image Processing Framework for Accuracy Measurements in Real-Time Endovascular Simulation

Sammanfattning

Training surgeons to navigate catheters and guidewires through blood vessels ischallenging, and simulators are increasingly used to practice these procedures safely.However, no standard method currently exists to objectively measure how realisticallya simulator reproduces the behavior of real surgical instruments. This thesispresents an image-based framework for the quantitative comparison of physical andsimulated catheter configurations, combining camera-based image acquisition, centerlineextraction, geometric alignment, and shape comparison metrics.Physical experiments were performed by imaging catheters and guidewires both onflat surfaces and inside a vascular phantom (Physical SIM). The same instrumentconfigurations were then reproduced in the Mentice simulator (VIST), allowing adirect comparison between the physical and virtual setups. The framework was furtherextended with an automated optimization module that searches for simulatorstiffness parameters that best reproduce the observed physical catheter behaviorusing Bayesian optimization.Validation experiments demonstrated high accuracy in catheter length estimation,achieving a mean absolute error of 0.117 cm and a coefficient of determination exceedingR2 > 0.99. It also remained consistent regardless of the catheter shape. Thealignment procedure showed that the extracted centerlines converge to a close geometriccorrespondence after registration. Optimization experiments further showedthat simulator stiffness parameters could be tuned to reproduce physical catheterconfigurations with high geometric similarity, although discrepancies remained forcertain catheter-guidewire combinations. A direct comparison between the physicaland virtual environments was additionally limited by fundamental differences inanatomy representation.The results demonstrate that the proposed framework enables quantitative and repeatableevaluation of endovascular simulator realism. Among the evaluated metrics,RMS error and curvature analysis were found to be the most informative: RMS errorfor localizing spatial deviations along the catheter shaft, and curvature analysis forcapturing mechanical differences in instrument bending behavior. The frameworkprovides a foundation for future validation and calibration of catheter mechanics inanatomically realistic simulation environments.