Université d'Auvergne Clermont1 | CNRS

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Axis 1: Training to Laparosurgery Gestures and Decision Making using Virtual Realty

Context

The training of surgeons to laparosurgery gestures and decision making is a fundamental step. The absence of 3D visualization, of tactile awareness and the indirect transmission of gestures through the entry point given by the trocar make gesture learning more difficult than in laparotomy. There exist two training centers in France (Clermont-Ferrand and Strasbourg) and five others in Europe. Apart from these centers, which cannot cover the need, training is done through companionship between surgeons and students, directly on patients in operating rooms. Clermont-Ferrand’s CICE proposes three main training steps: eye-hand coordination via the manipulation of rigid objects, practice on pigs and companionship. A possibility which has received little attention so far is simulation via virtual reality. The existing simulators (SimSurgery, used in Clermont-Ferrand, LAP Mentor from Simbionix and LapSim from Surgical Science) are restricted to purely “mechanical” gesture training: they do not teach the surgeon decision making with respect to the different possible options during surgery (for instance, when putting up a trocar, it may happen that a blood vessel gets hurt and requires a rapid intervention of the surgeon). Moreover, the existing models of the peritoneal environment are not realistic, and are yet far from being able to replace practice on pigs.

Clinical and technological objectives

The main clinical objective of this axis is to improve training thanks to the development and use of simulation tools based on virtual reality. Training will only be efficient if the user feels immersed in the simulated environment and can identify, objectively and/or subjectively, the simulation to a real case/patient. This awareness feeling depends on several factors including the hardware being used, the scenario, etc. One can in particular differentiate, for the application at hand, the notions of objective presence (the capacity of one to correctly make tasks in the virtual environment) and subjective presence (the feeling of being present in the virtual environment). So as to make an immersive experience appropriate for training, it is necessary to reach a level of realism in several respects: visual, dynamical (deformations in response to the surgeon’s acts), interfacing (choice of the simulator’s devices) and above all behavioral and in terms of events (for instance unexpected events or events triggered by the teacher) contributing the feeling of immersion.

Technical issues

The technological problems induced by our objectives of training are the following:

  • High quality visual and dynamical modeling of deformable models and fluids representing the different tissues, organs and bleedings, in collaboration with ALCOV’s axis 2. The main difficulty is related to the fact that the simulator will be directly compared to the animal model. Realism and closeness to this model are the two main objectives of our modeling. They are difficult to reach: the first results obtained by IFMA (Institut Français de Mécanique Avancée) for CICE using the SOFA Framework have not been convincing for the surgeons. So as to reach our objectives, two ways will be followed: (i) the understanding of the level of realism needed by the surgeons and (ii) the mastering and enhancing of techniques for the dynamical modeling of deformable objects and for visual realism.
  • Formalizing the students’ evaluation criteria by the surgeons, so as to implement a system for task- and procedure-tracking. These criteria are very often subjectives and so are difficult to model in a software application, which has the objective to let the students to self-evaluate. This phase necessitates an important and deep communication between the surgeons on the one hand and the computer scientists on the other hand, so as to find objective criteria and/or solution to facilitate objective evaluation for the teacher.
  • Measuring the presence awareness. For our simulator to be efficient and used, it has to reach the level of the animal model and at least as attractive. This attractivity is related to several factors of the user’s presence awareness in the simulator. If the student feels concerned and concentrated, and undergoes real surgery conditions, then the simulator will be used and enjoyed. Unfortunatelly, measuring the presence awareness is complicated and related to the application at hand. It is thus difficult for one to directly use results from the literature. Our measuring methodology will use success criteria (duration of training, percentage of tasks being done properly), physiological factors (heart pace, sweating, muscular activity…), reactions to unexpected events and subjective surveys (during or after the training period).

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