Kevin
M. McNeill, Ph.D.
Research Asst. Professor,
Dept. of Radiology & Dept. of Pathology
Assoc. Director for Network Architecture, The Arizona Telemedicine Program
The University of Arizona, Health Sciences Center
Michael
Holcomb.
Network Manager, Dept.
of Radiology & The Arizona Telemedicine Program
The University of Arizona, Health Sciences Center
Theron
W. Ovitt, M.D.
Professor and Head,
Dept. of Radiology
The University of Arizona, Health Sciences Center,
Ronald
Weinstein, M.D.
Professor and Head,
Dept. of Pathology
Director, The Arizona Telemedicine Program
The University of Arizona, Health Sciences Center
ABSTRACT
During the last several years telemedicine has gained increasing acceptance and many studies have demonstrated its clinical effectiveness. The technology available to support telemedicine activities continues to undergo rapid evolution. This rapid change has the benefit of acting to generally reduce the cost of telemedicine, while also presenting a significant challenge to those attempting to evaluate the impact of the technology and compare it to face-to-face clinical encounters. Among the rapidly evolving areas of technology critical to telemedicine is that of telecommunications.
In July of 1996 the Arizona Telemedicine Program (ATP) was initiated by the state legislature as a response to the increased recognition of the needs of under served populations in the state. The large size of the state of Arizona imposes difficult distance constraints which can be best met through the use of networking and computing technologies to support health care delivery, education and research. The legislature funded an eight site network as a general appropriation to The University of Arizona Health Sciences Center's operating budget. Two important goals for the program are to: establish a statewide telemedicine network infrastructure; and to use that infrastructure as a test bed for various state agencies to evaluate the effectiveness of state-of-the-art telemedicine services.
We have built a network based on leased T1 services. We evaluated technology options to use over this infrastructure. Initially we looked at the traditional hub and spoke technology used for video conferencing in which all circuits terminate at the central location and a multi point control unit and switching equipment supports the video conferencing application. The architectures proposed by video conferencing vendors were oriented toward this centralized approach and were typically very weak on data integration. This architecture did not fit our need for two key reasons. First, a distributed infrastructure was a better fit with our design principles and our budget constraints. Second, static allocation of bandwidth would inhibit optimal use of the T1 circuits. We then evaluated Asynchronous Transfer Mode (ATM) technology and found it to be a better fit with our design principles. Recent trends in the industry had also made it much more affordable that it had been in the past. We were able to find inexpensive end equipment which supports ATM over T1 circuits and rovides dynamic allocation of bandwidth between video and data applications. In addition, the device provides a LAN interface that allows us to support data applications without requiring an external router. The same vendor also offered very scalable and affordable ATM switches for the backbone which could support a variety of communications media ranging from DS1 to OC12 (622 Mbps) with switching capabilities that can be expanded incrementally from 2.5 Gbps to 10 Gbps.
The ATP wide-area network now supports eight clinical sites with communications over a low-speed (T1) based ATM network and several other sites which communicate over dial-up phone lines. At the the Arizona Health Sciences Center both ATM and LAN infrastructure is distributed through-out several clinical areas. This distribution allows physicians to support telemedicine activities where they normally work rather than requiring them to go to a special telemedicine location. The first site come on-line in July of 1997 and subsequent sites have been brought on-line every three or four months. Between July 1997 and March of 1998 over 900 telemedicine consults have been performed. The selection of ATM technology has proven to be very flexible and allowed us to incrementally expand the features and services we are able to support over the network.
Correspondence:
Kevin M. McNeill, Ph.D. Research Asst. Professor,
Dept. of Radiology & Dept. of Pathology Assoc.
Director for Network Architecture,
The Arizona Telemedicine Program
The University of Arizona,
Health Sciences Center,
Tucson AZ 85724
Oral presentation at EuroPACS'98, Barcelona, Spain