Evaluation of telemedicine systems can focus on a variety of technical properties, including data transmission speed or bandwidth, data quality (e.g., resolution), system functions and features, ease of use, reliability, and service or maintenance requirements. These properties are at the core of one of the most challenging aspects of telemedicine evaluation, i.e., the "moving target problem," where many technologies used in telemedicine are undergoing continual change. Technical properties such as bandwidth and resolution are steadily improving, while the costs to achieve given levels of technical performance are decreasing. In many cases, the technology is improving on a yearly basis, improving the ability of health care providers to make accurate diagnoses via telemedicine (for example in conducting dermatology consultations), and making the application more user friendly (for example with use in home health care).
When the lifecycle of certain key component technologies of telemedicine is shorter than the evaluation cycle, the findings of such an evaluation can be outdated and misleading. The evolution of technology involves diversification as well as substitution of new for old. According to a recent buyer's guide, categories of videoconferencing technology alone include: interactive video room systems and rollabouts, specialized telemedicine rollabout units, computer-based desktop videoconferencing units, videophones, laptops, set-tops, hand-held mobile, and wireless communications and data systems (Telemedicine 2000 Buyer's Guide & Directory, 2000). This "moving target" problem is not unique to telemedicine. Telemedicine evaluations should be designed to account for these moving targets.
Among our interviewees, the two most widely cited of the technical issues were greater bandwidth and the impact of the Internet on telehealth (including the accompanying security and confidentiality issues). Bandwidth refers to the amount of data that can be transmitted in a fixed amount of time. Thus, greater bandwidth allows for more data to be transmitted more quickly. As demand and use of bandwidth increase in all areas of telecommunication, associated costs of each individual area of use will decrease. As other applications use bandwidth, the cost burden on any particular application, including telemedicine, will be reduced. Greater bandwidth enables greater resolution, use of real-time vs. store-forward images, full-motion imaging, and other properties that will expand the technical capacity of telemedicine.
The Internet has considerable potential as a medium for teleconsultations, monitoring patient condition, and other unforeseen applications in telemedicine. Use of the Internet for teleconsultations and other telemedicine applications will move these applications into the mainstream of other communications used by physicians and other health care providers, decreasing the need for separate facilities (equipment, space, etc.), procedures, and telecommunications standards for telemedicine. As many of our interviewees emphasized, any developments that reduce the "separateness" of telemedicine from other parts of the health care system will improve its acceptance and efficiency.
As noted by the Association of Telehealth Services Providers, the potential impacts of the Internet and greater bandwidth in advancing the technical properties of telemedicine are linked:
The Internet has become the common standard for transmission of nearly all types of data, including web-based data transfer, audio, and video. The reason that we don't use the Internet more for all of these things is that the bandwidth and switching capacity is not there. These will clearly grow in time, however, making the Internet Protocol the lingua franca of data transmission of all types. In the next ten years, virtually all telehealth transmissions will happen using Internet Protocol, whether or not the transmissions happen over the Internet. As Internet capacity grows, we expect that nearly all telehealth transactions will be done via the Internet. -- Association of Telehealth Service Providers (2000)