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Tele-3D-computer assisted surgery – new experience in the development of modern otorhinolaryngology

Technological systems of medical diagnostics are most appropriate for the use of computer technologies, because they actually are computers. All up-to-date diagnostic devices possess the software and interface for connection to computer networks by use of DICOM protocol. The introduction of computer technologies has allowed the patient's images to be simultaneously analyzed on a number of users' computers within a local computer network (operating rooms, lecture rooms, etc.). Storage of the patient's images and diagnoses in a multimedia form in computer systems allows them to be subsequently searched and some specific cases re-examined for analysis and physician education, even via Internet (e.g., Eurorad Project). The storage of data in the computer system by use of DICOM protocol (Figure 1) is very important when the image information are to be used for more complex testing and examination, e.g., for precise delineation of subtle anatomic features, of the pathologic and healthy tissue on complex spatial models (3D volume rendering), or by use of VE or VS during preoperative preparation (diagnosis, preoperative planning), conduct of operation, or analysis of the course of operation in the “ standard surgery” and/or telesurgery. In this way, 3D reconstruction of anatomic units becomes a routine preoperative procedure that provides a highly useful and informative visualization of the regions of interest9, thus bringing advancement in defining the geometric information on anatomical contours of 3D model by the transfer of so-called image pixel to contour pixel. With defining the procedure of the use of advanced techniques of computer analysis of image data, the 3D method of visualization represents a significant scientific contribution which has also been demonstrated to be of immediate practical value, especially in Tele-3D-C-FESS in otorhinolaryngology. Subsequent computer analysis of digital CT or MRI image information, translating them from 2D into the 3D form, allows for a reliable diagnosis to make, especially on defining precise localization and spread of the pathologic process. Telesurgery, as a specific part of telemedicine, consists of two or more ORs connected with a computer network. Through this network, two encoded live video signals from the endocamera and OR camera are transferred to other remote locations involved in the telesurgery/consultation procedure. Our telesurgery approach, Tele-3D-C-FESS, allows surgeons not only to see and to transfer video signals but also to transfer 3D computer models and surgical instrument movements with image/3D-model manipulations in real time during the surgery. We use JPEG and MPEG2 encoders and decoders, ATM communication equipment, graphic workstations, 3D digitizers and standard endoscopic surgical instruments. The new video encoders using MPEG2 standards and ATM computer networks using inverse multiplexing greatly improve the safety of surgical procedures, especially in endoscopic surgery. The best results are obtained using ATM-OC3 technologies, with the most acceptable price-performance using the inverse multiplexing method across 4-8 E1 lines. Our 1st TS used M-JPEG compression over ATM (OC-3, 155Mb/s). Also, at each of the four locations involved in the telesurgical procedure, there was a remotely controlled video switch with 8 video inputs and 8 video outputs. At the expert location, remote from the OR, there was a video processor for the acquisition of all video signals from all sites involved in the telesurgery procedure and software for the remote control of all video inputs/outputs and pan/tilt/zoom cameras of all locations. Thus, from this point in the telesurgery network, a consultant or conference moderator can view all the video signals or just the primary display. For all these possibilities, a bandwidth of at least 155Mb/s (ATM OC-3) is needed. The 2nd TS procedure was transmitted over four T1 lines, each about 8Mb/s of bandwidth, and better compression standards, such as MPEG1/2, were used. There was one video stream from every site involved in the telesurgery procedure. At the OR location, a manually controlled video switch for switching between the endocamera and the conference camera was used. The full frame video signal was transmitted from every location to any other location through MPEG1/2 encoders/decoders and inverse multiplexing switches. Video signal processing was not possible because of lower bandwidth (only 8Mb/s). In our 1st TS, ATM switches and AAL-5 were used for video transmission and native or LANE for TCP/IP computer communications. The 2nd TS procedure was built over inverse multiplexing technologies (4xT1 lines), with TCP/IP computer communications. There also was one spare ISDN line (64Kb/s) for redundant conferencing, video conferencing. In our 1st TS, there was communication between all sites using InPerson teleconferencing software and the native TCP/IP network. Consultations using computer images and 3D-models were performed using the video network ; outputs from the computer were encoded into video stream and transmitted to the remote locations through video communication protocols. In our 2nd TS, standard T.120 collaborative tools (SGI meeting, NetMeeting) were used. Both locations involved could view images and 3D-models and manipulate them with software on the local, expert location. We used OmniPro software on top of SGI meeting tools. The use of an endocamera allows recording of the complete surgical procedure in two different media: Video Tape and MPEG Stream. In postoperative analysis, MPEG2 stream records can be synchronized with movement records of the spatial localizer to produce animation of the computer 3D model based on the real surgical procedure. In addition, encoded MPEG2 and MPEG1 streams from the telesurgery procedure to the SGI Media Base Server and MS Net Show Theatre were recorded. Thus, users in our local network can view the recorded procedures with standard viewers using the video on demand system. Endoscopic, computer and communication technologies are very sophisticated and very exciting but "what if something goes wrong" during the telesurgical procedure? That is why we need to build a default tolerant system with multiple, redundant endoscopic, computer and communication equipment and paths.

Telemedicine; telesurgery; 3D; computer assisted surgery; otorhinolaryngology

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