Most definitions found in this glossary are adapted with permission from this text book:

Maheu, M., Whitten, P., & Allen, A. (2001). eHealth, Telehealth & Telemedicine: A Guide to Startup and Success. New York: Jossey-Bass.

Browse the glossary using this index

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Data compression

A technique that removes extraneous characters and reduces data volume, thereby decreasing image processing demands, transmission times, bandwidth requirements, and storage space requirements. As distinguished from "lossless" compression techniques, "lossy" ones drop some information, which may or may not be clinically important, depending on the specific telehealth application.
Entry link: Data compression


Describing a permanent telephone or data line that is reserved exclusively for one specific purpose. Dedicated lines are usually digital and are also referred to as leased or private lines.
Entry link: Dedicated


Digital Imaging and Communications in Medicine. A set of protocols describing how radiological images are formatted and transferred from point-to-point digital medical imaging devices. DICOM was developed by the American College of Radiology and the National Electronic Manufacturers Association (ACR/NEMA).
Entry link: DICOM

Digital image

An image formed by independent pixels, each of which is distinguished by a digitally represented luminance level.
Entry link: Digital image


The conversion of analog information into digital information. Digital signals transmit audio, video, and data coded as bits. Digital technology facilitates data compression, and digital signals are less susceptible to interference than analog technology.
Entry link: Digitization

Distance Education

Distance education is defined as a formal educational process in which the majority of the instruction occurs when student and instructor are not in the same place. Instruction may be synchronous (students and instructors present at the same time) or asynchronous (students and instructors access materials on their own schedule).
Entry link: Distance Education

Distant Site

(see also Hub Site or Consultant Site) Is the telehealth site where the provider is located when delivering a telehealth service.


Entry link: Distant Site


The transmission of data from a satellite to a receiver on the ground.
Entry link: Downlink


Allowing telecommunication in opposite directions. Full-duplex communication channels can transmit data, audio, or video simultaneously; half-duplex channels can transmit in only one direction at a time.
Entry link: Duplex

Durable Medical Equipment

(DME) Is any medical equipment, such as oxygen tanks, wheelchairs or hospital beds used in the home. Newer DME devices include peripherals for smart devices.

Entry link: Durable Medical Equipment