Extending broadband for radiological advances

Communications News, Oct, 1991 by Stephen Fath

The University of Texas Medical School in Houston cost-effectively revolutionized the way doctors receive and handle X-rays and other medical images by tapping into the existing campus broadband architecture.

Couriers are no longer needed to carry films between hospitals. Now, radiologists can consult with their colleagues via a computer screen. Medical images are digitized and sent over the broadband Ethernet to personal computers where they can be viewed using high-resolution monitors.

Doctors no longer will have to be in the lab or in front of a light box to view images. They can pull up images from the hospital server using PCs directly from their offices or clinics. Availability of images via Ethernet is particularly useful in a university atmosphere where data are often shared.

From an educational perspective, doctors who teach find the ability to manipulate images provides an added dimension in the classroom.

Implementing this innovative application proved to be a learning experience for the medical school.

When the radiologists identified the need to transmit images between hospitals, they considered other options. ISDN trials were used to transmit X-rays between facilities at first.

While fiber accommodates the faster transmission speeds needed--about 10 Mb/s, it would have been an expensive option for the state-funded institution due o the distances between hospitals and other buildings involved. And ISDN is limited to 64 kb/s transmission and generally used at 19.2 kb/s, while 10BROAD-36 transmits at 10 Mb/s.

During a search for a solution, it was pointed out there was no need to venture outside the university and hospital complex for such a service. The University of Texas Health Science Center had been using broadband for a number of years and had implemented a campus-wide Ethernet. The network had room for expansion and the cost of access would be a modem, headend remodulator, and the cost of implementing LANs in the appropriate locations, a necessity in any case.

The present network has approximately 500 nodes and interconnects 23 buildings in the Texas Medical Center. It is growing at a rate of about 40 nodes per month. Connections to remote medical facilities staffed by the medical school are provided via a combination of private microwave and leased lines.

The hospital needed a solution that would allow it to implement a high-density application without interfering with the research, administrative, and educational network traffic. When the system is in full swing, more than 500 2-Mbit files will be transferred daily.

A second Ethernet channel was added to the broadband cable in anticipation of these needs. Since the cable is also used for 17 channels of educational video and other non-Ethernet data traffic, finding a place for the new network was a problem.

Broadband modem manufacturers generally provide a standard set of frequencies for Ethernet transmission on broadband. Modems which would transmit and receive on the available frequencies could not be bought off the shelf.

Fairchild Data Corp. provided a rapidly modified M8023 modem and HR8023 headend remodulator to accommodate the need for off-channel transmission of medical images. By incorporating Fairchild Data's extended distance option, the coverage area was extended from about two miles to three.

The second Ethernet was added to accommdate the image processing, which requires files much larger than for normal data-transmission requirements. The second broadband Ethernet extends the standard 802.3 distance coverage by 25%.

The medical school is one of the first users to implement the extended distance option. It provides the ability to expand well beyond the IEEE 802.3 minimum standard transmission coverage area of 3600 meters to 4500 meters, while still using a headend remodulator to minimize interference with adjacent services.

The new extended distance option allows the broadband modem to achieve maximum coverage in an Ethernet environment. Additionally, the extended distance option on the data modem can be combined with standard modems on the same cable plant.

A modified modem and headend remodulator expanded the broadband uses, and implementing the standard options of those devices cost far less than implementing an entire new network of fiber.

Combining an off-channel option along with the new Ethernet, there is a great deal of room for expansion. An additional channel adds flexibility to the system and gets the most out of broadband's multi-media capabilities by using the cable plant to its full capacity.

Dr. Stephen Fath, Director Educational Computer Services, University of Texas Medical School