PHILADELPHIA - The growing availability of fast and inexpensive communications approaches such as cable and digital subscriber lines (DSL) offers the possibility of dramatic performance and economic improvements for teleradiology users. At this week's Symposium for Computer Applications in Radiology, researchers from the Ohio State University in Columbus discussed their first year of experience using a cable modem for Web-based remote image access.
While Web-based access was available on-site over the hospital's in-house asynchronous transfer mode (ATM)-powered local area network, the researchers also wanted to offer access to PACS images for after-hours subspecialty radiology consultation. But transmission speeds are a critical determinant for the viability of this application, according to Dr. William Bennett.
To test the speed of the cable modem, the researchers performed a series of tests over an 18-hour period, remotely accessing three CT scans, three CR studies, and a MR image. The images on the Web server were full 12-bit images archived in a lossless 3:1 format. The radiographs were displayed in an average of 19.7 seconds, while the cross-sectional studies (16 images) were seen in 14.9 seconds.
In contrast, display of images over the hospital intranet was achieved for radiographic studies in 6.7 seconds, and cross-sectional exams in 7.4 seconds. The researchers did notice a slowdown in image transmission times during evening periods, when more users accessed the cable network.
Although not much slower than the hospital intranet, cable modems do engender security concerns. Cable modems run off a set Internet protocol (IP) address on a unprotected network, creating an opportunity for hackers, Bennett said. In fact, Ohio State's IS department was a little leery at first about allowing cable access to the network, he said.
"Not only could a hacker get into your computer, but they could piggyback onto the current session you have at the hospital and get through the hospital firewall," he said.
To combat this security vulnerability, Ohio State employs a virtual private network (VPN), a secure ID password system, and data encryption to access the firewall-protected hospital network. The institution uses Impax PACS software from Agfa of Ridgefield Park, NJ, along with the vendor's Web 1000 image access product.
By Erik L. Ridley
AuntMinnie.com staff writer
June 6, 2000
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