Interactive patient-customised simulator offers surgeons real life "plan, train and rehearse" experience

Manchester 04 February 2000In Europe, the integration of advanced technologies such as 3D visualisation, virtual reality, and computerised simulation for pre-operative planning, performance and training of surgical procedures is rapidly gaining in interest. Funded by the European Commission's IST Programme, a team of eight partners is setting up an Integrated Environment for the Rehearsal and Planning of Surgical Interventions (IERAPSI). The IERAPSI consortium will particularly focus on the planning, simulation, and training of surgical procedures performed on the petrous bone, a common site with a complex anatomy. The system will address frequently applied interventions, such as mastoidectomy, but equally very exacting ones, like cochlear implantation and acoustic neuroma. In a later stage, IERAPSI might also be used for other surgery specialities.


A typically innovative feature of the IERAPSI project constitutes the use and manipulation of patient specific visual data instead of standard available anatomical material. As a result, the intervention can be optimally planned for and tailored to each patient, while the surgeon is able to explore alternative approaches to the solution of individual problems or constraints. To this purpose, IERAPSI will build an interactive visualisation environment to allow the production of 3D surgical planning data sets. The partners who are responsible for the system's development therefore have to design image review and analysis tools for the surgical review of CT, MRI and angiographic examinations in an interactive 2D and 3D manner.

The open architecture equally has to encompass an integrated suite of image segmentation and visualisation tools, which will allow for a fast and accurate identification of individual structures based on their imaging characteristics. In addition, a physics based surgical simulation system is needed with visual and haptic feedback for trainees to perform operations on individual patient data. The implementation will be generic in order to easily adapt and re-use components for other applications. IERAPSI has to deliver its results in three years' time following the explicit, logical steps of the ergonomic task analysis. The major goal consists in contributing to the European Community's social objectives by optimising the provision of health and life via the introduction of modern science technology into health care.

To accomplish this aim, the strategic plan involves the development of both an integrated suite of tools for pre-operative planning and an infrastructure for training and rehearsal of surgical operations based on the data produced by the pre-operative tools. In order to present the medical data in stereo 3D, an autostereoscopic display subsystem will be engineered. This can be linked to the pre-operative planning system and to the virtual reality trainer as if it were a conventional monitor. The autostereoscopic 3D display forms a user-friendly alternative to shutter glasses, offering a full brilliance of colours and brightness and the possibility of quasi-holographic visualisation. In the end, the pre-operative tools and the training infrastructure have to be integrated on the basis of a standardised data format, in order to facilitate the exchange of the processed medical data between the IERAPSI components and external entities.

The IERAPSI project will follow an iterative development cycle to ensure that the final version will fully meet the initial requirements of the end-users. In this regard, the usefulness of the IERAPSI system will be assessed by a small scale clinical trial, addressing each of the three clinical exemplars, which are pre-operative planning, surgical simulation training and rehearsal of surgical procedures. The trials will be conducted by three end-user partners at the University of Pisa, the University College of London's Institute of Laryngology and Otology, and the University of Manchester, which is also the IERAPSI co-ordinator. Clinical trials will be performed using a standard bank of clinical test data which will be read into the IERAPSI system and presented to the subjects.

The IERAPSI consortium has the firm intention to introduce the system into the daily routine of clinical practice, and to develop a commercial version of the interactive planning and rehearsal environment. In the future, IERAPSI may even be used in patient education and consent to prepare the individual before a surgical intervention by explaining the procedure a patient is about to undergo, using renderings of his own body. Next to the end-user partners in the team, five other institutions and companies will contribute to IERAPSI and its successful design, exploitation, and dissemination. These are CRS4, the Italian simulation expert; the British and French VR specialists, Virtual Presence and CS Systèmes d'Information; the Dresden University of Technology, designer of the autostereoscopic display; and Genias Benelux, the Dutch company providing the tools for the project's dissemination and exploitation via the IERAPSI Web site.

Leslie Versweyveld

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