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Tele-3D-CAS in Otorhinolaryngology

Endoscopy, as a surgical technique, is based on the implementation of very complicated technology. FESS, as an endoscopic operation, is performed with the use of "live image" via an endoscope, endomicrocamera, cold light sources and video equipment. We have also added a high performance computer, surgical field videocamera and spatial localizer with mounted surgical instrument. At present, every physician (scientist and clinician) using computer for diagnostic (e.g., radiology) and therapeutic (e.g., surgery) purposes should know that images are processed by use of graphic and computer systems as well as by specialized program systems, in order to better present the anatomy of a particular part of the body with identified diseased areas. Beside otorhinolaryngology , this has also been used in other fields. The more so, in addition to educational applications, VS has offered us the possibility of preoperative planning in sinus surgery, and has become a very important segment in surgical training and planning of each individual surgical intervention. In the activities of our 3D C-FESS team, these analyses are becoming routine procedures, as well as in other ENT centers elsewhere, for oral, maxillofacial and plastic surgery. The basic goal of our 3D C-FESS (www.mef.hr/3D-CFESS) and Tele-FESS (www.mef.hr/Tele-FESS) with 3D-computer assisted support (Tele 3D C-FESS) (www.mef.hr/MODERNRHINOLOGY) is to achieve safer surgical procedure using new computer and medical technologies in telesurgical consultation, and provide visualization of the anatomy as well the pathology in the 2D-black and white form as well as in the form of 3D-models. So, using our own approach in C-FESS, we were able to "look inside" the patient during the real surgical procedure. According to our original idea, the computer network, essential for computer collaboration between telesurgical sites, has to be built in parallel to the video network. Every telesurgical site must have compliant collaboration software. On computer workstations, all sites have CT images and 3D models with movies. The consultant, an experienced surgeon, assists the less experienced surgeon to reach the pathology in the operating field. This kind of our Tele-3D-CAS has to enable less experienced surgeons to perform critical surgeries using guidance and assistance from a remote, experienced surgeon. In telesurgery, more than two locations can be involved ; thus less experienced surgeon can be assisted by one, two or more experienced surgeons, depending on the complexity of the surgical procedure. Our Tele-3D-CAS provides also the transfer of computer data (images, 3D-models) in real time during the surgery and, in parallel, of the encoded live video signals. Through this network, the two encoded live video signals from the endocamera and OR camera have to be transferred to the remote locations involved in the telesurgery/consultation procedure. During telesurgical transmission, two video signals have to be transferred from the OR site and one video signal from every remote site involved in the telesurgery procedure. As about 24 Mb/s of bandwidth are needed for the native video signal, and there are only 155 Mb/s or multiple 2Mb/s lines of bandwidth, the video signals must be compressed using standard video compression systems. 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. ATM switches and AAL-5 were used for video transmission and native or LANE for TCP/IP computer communications. InPerson teleconferencing software and the native TCP/IP network was used for communication between all sites. 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. The advantage is that only standard video equipment, without any type of computer, needs to be installed at the remote location ; the disadvantage is the image or 3D-model from the local computer can only be viewed at the remote location and cannot be manipulated with computer software. Video records of the procedure, MPEG streams of the procedure in combination with CT images and 3D models are essential for the creation of a computer database system for education and the preparation of future surgical procedures (Broadcasting, Tele-education, DVD-ROM, CD-ROM, www). In the real procedure, 3D computer models (Open Inventor) can be texture-mapped using the live video signal from the endocamera. The live video signal can be positioned using a 3D digitizer or any other spatial localizer. The texture mapped 3D model, with live video signal during the surgery, provides the surgeons with a more realistic computer presentation of the real surgical field. In our preliminary tests and the 1st telesurgery, we used the following: • SGI O2 workstation, • Newbridge ATM Switch, • ATM switched networks, • Video streams over AAL-5, • Computer communications over LANE (TCP/IP), • 3Com Inverse Multiplexing (4xT1), • Optivision MPEG1/MPEG2 encoders, • Newbridge M-JPEG/MPEG1/MPEG2 encoders, Network topologies: • point to point T1 lines, • nonroutable/routable shared FastEthernet/Ethernet, • nonroutable/routable switched FastEthernet/Ethernet, • ATM switched networks with AAL-5 and LANE, • multiple T1 lines (today). Usage of collaboration tools (H.120, H.323): • SGI InPerson (Video, Audio, WhiteBoard), • SGI Meeting (Whiteboard, Application Share/Collaboration), • Microsoft NetMeeting(Video, Audio, Whiteboard, Application Share/Collaboration), • StarVison StarMED, StarED.

Telesurgery; 3D; CAS; tele-CAS; otorhinolaryngology

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