Evaluation of robotic surgery skills using dynamic time warping

Abstract

Background and Objective: accompanied with the wide acceptance of robot assisted minimally invasive surgery (RMIS), the demand for efficient and objective surgical skills evaluation method is increased. Recently, with the development of medical engineering technology, several evaluation methods have been proposed. Among them, kinematic analysis, an unsupervised and data-based method, has been accepted by many researchers. However, this method is still limited by the number of metrics and unconvinced scoring system. This paper aims to propose a new evaluation method to assess surgical skills efficiently and objectively.Methods: this research proposed an efficient and effective surgical skills evaluation algorithm which used the trajectories of instrument tip and dynamic time warping (DTW) to provide trainees with real-time and summative feedback. The optimum trajectories based on ‘Therbligs’ theory was designed as a template. DTW algorithm was used to align actual trajectories to optimum trajectories with an evaluating indicator designed to emphasize the crucial motion features in surgical skills evaluation. The real-time feedback was obtained through a sliding time window to help trainees improve learning efficiency.Results: experts (n = 2) and novices (n = 8) were invited to complete the peg transfer tasks and 60 instrument tip trajectories were assessed by the proposed algorithm. Significant differences between different groups were observed (experts’ right trajectories versus experts’ left trajectories, p = 0.0002; experts’ right trajectories versus novices’ right trajectories, p = 0.0124). In addition, evaluation results of trajectories with operational mistakes were significantly different from those of others.Conclusions: the proposed evaluation method showed its advantages in distinguishing and evaluating surgical performance. Given its ability to evaluate the performance based on kinematic information, the proposed evaluation method can be further developed in the future. Furthermore, because the proposed method can provide real-time feedback, it also has the potential to be a monitoring system in operation room.