engleski

3D-computer assisted surgery and Tele-3D-computer assisted Surgery: Virtual surgery prior the real operation

The main message of our tele-3D-C-FESS surgery, as differentiated from the standard telesurgeries worldwide, is the use of the 3D-model operative field, and thus of VS (Figure 9). This is of paramount importance for emergency surgical interventions. We would like to underline that no Tele-3D-C-FESS procedure was performed by a “ novice surgeon” who had not yet mastered the basic FESS techniques, nor is this type of tele-surgery intended for them. We do not advocate that “ surgeons beginners” operate on patients, not even with “ guidance of a remote surgeon” . Considering the specificities and basic features of Tele-3D C-FESS, we believe that this type of surgery would be acceptable to many surgeons all over the world. The 1st kind of our Tele 3D C-FESS took place between two locations in the city of Zagreb, 10 km apart, with interactive collaboration from a third location. A surgical team carrying out an operative procedure at the Šalata ENT Department, Zagreb University School of Medicine and Zagreb Clinical Hospital Center, received instructions, suggestions and guidance through the procedure by an expert surgeon from an expert center. The third active point was the Faculty of Electrical Engineering and Computing. The 2nd Tele 3D C-FESS took place between two locations, two cities in Croatia (Osijek and Zagreb, 300 km apart). The surgical team carrying out an operative procedure at the ENT Department, Osijek Clinical Hospital, received instructions, suggestions and guidance through the procedure by an expert surgeon and radiologist from the Expert Center in Zagreb. This Tele 3D C-FESS surgery, performed as described above, was successfully completed in 25-30 minutes. Taking into account the opinion of the leading world authorities in FESS surgery, we believe that each FESS operation is a demanding procedure, including those described in the two Tele-3D-C-FESS surgeries presented. Nevertheless, we would like to underline herewith that ordinary, and occasionally even expert surgeons may need some additional intraoperative consultation, for example, when anatomical markers are lacking in the operative field due to trauma (war injuries) or massive polypous lesions/normal mucosa consumption, bleeding, etc. Computer communications and collaboration in our Tele-3D-C-FESS based on CT images and 3D models between two locations worked well, but the video image quality was inadequate for telesurgery procedures because images of 320x240 pixels with only 5 frames per second were transferred. The basic video image as a standard record of the operation was only used as a standard record of the course of operation. Using routable shared and switched Ethernet connections, 25 frames were transferred per second in full PAL resolution but with 20% of dropped frames. After some tests, it was found that the routing protocol between two or more sites could not offer a constant frame rate. Packages sent from the source travel to the destination using different network paths, thus some packages may be lost during communication or some may reach the destination with unacceptable delays. For all these reasons, experimental links were introduced using ATM (OC-3) protocol with AAL-5 for video transmission and LANE or native TCP/IP data communication. Another problem we faced with video signals was how to transfer multiple video signals to remote locations. The native, uncompressed video required a bandwidth of about 34Mb/s, thus the video signals had to be compressed for the transfer of multiple video streams to remote locations using 155Mb/s. The video image is critical in teleendoscopic surgery and must be of the highest quality. Using software and hardware M-JPEG compression, it was found that one video stream from the endocamera in full PAL resolution and with audio required a bandwidth of about 20-30Mb/s. Our M-JPEG encoders were upgraded with MPEG1 and later with MPEG2 encoders, because we had a bandwidth of only 155Mb/s for data, video, audio and control communication. MPEG1 seems very good for conferencing ; however, the endoscope video signal of the operating field required better image quality.

3D; computer; assisted surgery; Tele-3D-computer assisted surgery; virtual surgery; real time

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