The 'Karlsruhe Endoscopic Surgery Trainer'

A 'Virtual Reality` based Training System for Minimally Invasive Surgery

1997 2002

(JPEG, 68 kB)

Series System VSOne, with fiber housing

To the benefit of the patients, Minimally Invasive Surgery and endoscopic procedures are getting more and more common in surgical practice. On the other hand, the indirect access to the operation area causes a lot of disadvantages for the surgeon: restricted vision, difficult hand-eye coordination and handling of instruments with limited mobility. Therefore the surgeon requires a lot of training and experience to execute an operation successfully and safely.

Goal and Benefits

Our goal is to support the teaching and training of the operators with a computer-based simulation system which imitates the operation area and provides a realtime 'synthetic` endoscopic view. The user can interactively manipulate the modelled objects and execute surgical tasks. The coordination of instruments, the hand-eye coordination and the teamwork can be practised, also the operation procedures and the use of new instruments. It is possible to implement several complications in a 'training parcours' as well as anatomic specialities. Structured training steps are repeatable and reproducible. An evaluation of training success can be performed, expert system feedback could be another useful feature.

Basic Principle

For laparoscopic procedures, we use a 'phantom box', a rough imitation of the outward human abdomen, with electromechanical instrument guidance and tracking systems. This realistic user-interface allows the trainee surgeon to manipulate the instruments in the usual way. Several different endoscopic cameras and surgical instruments can be imitated (geometry, kinematics, functionality).

Central unit is a high-performance graphics workstation with the simulation system 'KISMET' used as core software. KISMET does all the necessary calculations and generates the virtual endoscopic view in realtime. For modelling and realistic simulation, a model-database is required which defines the geometrical shapes and the physical/mechanical properties of the tissues, organs and vessels as well as the geometry and kinematics of the instruments. A knowledge-base specifies the interaction behaviour and the handling of the model manipulation.

Of great importance is the realistic imitation of soft tissue with its physical behaviour, which leads to 'deformable objects'. The relevant operation area in the training scenario is modelled by a coupled system of deformable objects. Another critical subject is the realistic simulation of the interaction between deformable objects and instruments and the manipulation of the virtual tissues. We have implemented so far several typical surgical tasks like grasping, cutting, coagulating and setting of clips. The calculation and representation of realistic tissue deformation and manipulation is done in realtime.

Additional important features enhance the realism of the simulation environment. Optionally, a full stereo view with shutter glasses is offered to gain a three dimensional impression. Further, we are developing a special instrument guidance system which provides tactile feedback. Other current work is the improvement of interaction realism (anatomical details, behaviour on surgical manipulation, bleeding) and the development of tools for automatical creation of models using MRI/CT-data sets.

Application

A prototypical scenario of a cholecystectomy was realized in our demonstrator, 18 frames per second are reachable and therefore an interactive manipulation of the virtual tissues is possible. The first commercial system of our 'Karlsruhe Endoscopic Surgery Trainer' was installed at the MIS-training centre of the University Hospital Tuebingen/Germany in autumn 1996. The software and models are updated frequently, an evaluation of the experiences and user feedback will be performed during this year (1997).

Virtual Endoscopic View (JPEG, 52 kB)

Other possible application fields of this system are:

We believe that computer aided surgical simulations could make a tremendous impact in improving teaching and training of surgical staff in the near future.


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Last modification: January 16, 1997.
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