Glossary
AAPM TG18
Acronym for American Association of Physicists in Medicine Task Group 18. Defines standard guidelines for the performance evaluation of electronic display devices intended for medical use.
ALC
Acronym for Ambient Light Compensation. A technology which continuously measures the amount of ambient light in the room where a display is being used. If the ambient light level rises or falls, the light output (i.e. luminance) of the display in question will be adjusted accordingly. If the level of ambient light in a reading room gets too high for dependable diagnostic reading, ALC will send an automatic alert via the MediCal QAWeb system.
Backlight
The illumination used in liquid crystal displays (LCDs). Backlights illuminate the LCD from the side or back of the display panel. Also see DuraLight.
BLOS
Acronym for Backlight Output Stabilization. A backlight stabilization system driven by a small sensor mounted at the rear of the display. If the lamps of a display dim over time (which is inherent to their ageing), BLOS compensates for the luminance drop by applying more power to the lamps.
CRT
Acronym for Cathode Ray Tube. A vacuum tube in which a hot cathode emits a beam of electrons which eventually hit a phosphorescent screen. This is a traditional means of displaying pictures on a monitor or television. CRT-based displays are often considered as bulky and heavy. Because of this, they are often replaced by lighter and more compact technologies such as LCD.
DICOM
Acronym for Digital Imaging and Communications in Medicine. A standard for handling, storing, printing, and transmitting information and pictures in medical imaging. It includes a file format definition and a network communications protocol.
DIN
Acronym for ‘Deutsches Institut für Normung’ (German Institute for Standardization). The DIN6868-57 guideline is a German standard, which, like the AAPM TG18, defines acceptance testing and constancy tests for medical display devices. Compliance with the DIN6868-57 standard is mandatory in Germany, Switzerland and Austria.
DL
Acronym for Diagnostic Luminance. A backlight technology capable of generating a DICOM-calibrated brightness of 800 cd/m². As a result, color, grayscale and fused modalities can all be read with diagnostic quality on the same display system.
DVI
Acronym for Digital Visual Interface. A connector interface for video displays and/or graphics accelerators.
DuraLight
A backlight technology characterized by exceptionally long lifetime. Compared to conventional Cold Cathode Fluorescent Lamps, average lifetime of DuraLight backlights is prolonged by a factor 3 to 5 without increasing power consumption or compromising visual performance of the LCD display system. Because of this, lamps no longer need to be replaced during the economic life span of a medical display.
EMI
Acronym for ElectroMagnetic Interference. An electrical disturbance in a system due to natural phenomena or waves from electromechanical devices or components.
Fusion
A display architecture replacing a dual-head display setup (very common in PACS imaging) by a single, wide-screen monitor without a hindering central bezel. Fusion gives radiologists more freedom to organize their workspace to their liking. It also facilitates side-by-side comparison of initial, prior and current studies, and it counteracts eye fatigue.
GSDF
Acronym for Grayscale Standard Display Function. A standard contrast curve, against which displays can be calibrated. With it, medical displays can be calibrated in order to ensure that images look the same when viewed on different workstations and at different times.
I-Guard
A tiny embedded photometer positioned at the front of the LCD screen. It has become the industry standard technology for monitoring the image quality and DICOM-consistency of diagnostic displays. I-Guard is an essential component of Barco’s Coronis family of radiology PACS displays.
IPS
Acronym for In Plane Switching. An LCD technology pioneered by Hitachi in which the alignment field is generated from electrodes located on a single substrate rather than on opposite sides as is the case in TN panels.
IPS-Pro
Acronym for In Plane Switching Pro. A highly advanced LCD technology. IPS-Pro substantially improves viewing angle, brightness, contrast, black levels and switching speed, producing the best solution on the market for multi-modality medical imaging.
JND
Acronym for Just Noticeable Difference. The smallest difference between colors or luminance levels a human eye can perceive.
Luminance
A measure of the brightness or intensity of light, usually expressed in Candelas per square meter (cd/m²) or foot Lamberts. 1 fL = 3.426 cd/m²
LUT
Acronym for Look-Up Table. A set of values in tabular form for input or output relationships. Most often associated with color calibration issues and determining how a color system translates from one color space to another.
OSD
Acronym for On Screen display. An image superimposed on a screen picture, commonly used by modern monitors to display information and user settings such as brightness, connections,...
PACS
Acronym for Picture Archiving and Communications System. Enables images such as x-rays and scans to be stored electronically and viewed on screens, creating a (near-)filmless process and improved diagnosis methods. It allows doctors and other healthcare professionals to access and compare images at the touch of a button.
PCI
Acronym for Peripheral Component Interconnect. A local bus standard for connecting hardware devices to a computer.
PCI Express
Acronym for Peripheral Component Interconnect Express. The most common port on modern computers for attaching components like dedicated video cards and sound cards.
PPU
Acronym for Per Pixel Uniformity. A technology which measures and adjusts the luminance of each pixel on a display and eliminates screen noise. As a result, every pixel is permanently compliant with the DICOM standard.
QA
Acronym for Quality Assurance. A program monitoring and controlling display performance and accuracy to ensure that the images shown on the screen are reliable, i.e. compliant with international medical standards (such as DICOM Part 14, DIN, AAPM TG18, etc.)
Response time
The time it takes for a pixel to turn on and off. In other words, how fast the display can refresh itself. Typically measured in milliseconds (ms). With a quick response time, you get better video quality. Low response times typically result in "smearing", “blurring” and "ghosting" artifacts on moving objects.
ULT
Acronym for Uniform Luminance Technology. This technology reduces luminance non-uniformities and color non-uniformities which typically exist between the center and the corners of an LCD screen. ULT reduces these non-uniformities and makes sure that the display is compliant with DICOM GSDF across the entire screen area.
Viewing angle
The maximum angle at which a display can be viewed with acceptable visual performance. This threshold value for contrast is usually set at 10:1
VESA mounting interface standard
Acronym for Video Electronics Standards Association. A family of standards defined by the Video Electronics Standards Association for mounting flat panel monitors, TVs, and other displays to stands or wall mounts. Originally, the VESA standard consisted of four screws arranged in a square, with the horizontal and vertical distance between the screw centers being 100 mm. For smaller displays, a 75 mm × 75 mm layout was defined.
