Barco I-Guard Features

Technology

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I-Guard® / Ambient Light Compensation

Maintaining image quality and DICOM-compliance under
all lighting conditions

Radiologists expect the quality of their medical images to
remain stable over time. Although the data stored in the
computer archive is purely digital and therefore stable over
time, the perceived image on a display workstation is not.
Aging and environmental changes can affect the perceived
image significantly. Therefore, displays intended for medical
use should have a means to stabilize the image quality and
maintain DICOM accuracy over time.

Another image stability issue is caused by the changing
ambient light conditions in the reading room, which can
influence the display’s performance and the radiologist’s
ability to detect subtle information. Therefore, there should
also be a way to ensure the display’s DICOM-compliance even
in changing ambient light conditions

I-Guard and Ambient Light Compensation (ALC)

Barco has effectively tackled the above-mentioned DICOM
consistency issues with two innovative technologies that
ensure worry-free DICOM compliance under all lighting
conditions: its patented I-Guard

technology and its Ambient

Light Compensation (ALC) system.

I-Guard

As an essential component of Barco’s Coronis
family of diagnostic displays, I-Guard has become
the industry standard technology for monitoring
the image quality and DICOM-consistency of

diagnostic displays.

The latest version of I-Guard

has been further perfected with
increased read-out speed and enhanced sensitivity down to
the lowest luminance levels.

The current generation I-Guard

technology brings:

• Perfect DICOM-compliance for both color and grayscale

display systems

• Much faster calibration speed

• Improved low light measurement performance

In addition to its application in grayscale diagnostic display
systems, the I-Guard perfectly meets the needs of color
display systems.

In color displays, a transparent color filter is stacked on top
of the Liquid Crystal Display (LCD). So, in order to properly
calibrate the luminance output of a color display, the sensor
has to look at the image the same way as the radiologist
does: from the front of the screen.

Barco’s I-Guard is a tiny, embedded optical precision
photometer positioned at the front of the LCD screen.
Contrary to backlight sensors, which are only capable of
detecting what they see (the backlight), I-Guard sees what
the radiologist sees: the result of the complete image
formation process of the LCD, including the graphic board,
the Look-Up Table, the driving electronics, the backlight
and the Liquid Crystal cells. I-Guard continuously monitors
the light output of the red, green and blue contributions
without disturbing the actual image display. The intelligent
I-Guard communicates its readings to the controlling
electronics, which make corrective actions to the LCD in real­time.

Side view of an LCD screen with I-Guard sensor

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In addition to its stabilizing function, I-Guard can precisely
measure and calibrate any DICOM Just Noticeable Difference
(JND) value as defined by DICOM Part 14 with 18-bit
precision.

I-Guard requires a few square millimeters at the edge of the
screen to do its job unnoticed in the background, without
disturbing the radiologist’s work. Whether it is overnight
when the screen is not used, or during a busy day while the
display is in use, I-Guard

can take readings from the small
test-patch displayed in the I-Guard area while a medical
image is on the screen.

Combined with Barco’s MediCal QAWeb softcopy QA tool,
I-Guard brings fast and easy calibrations, automatic Quality
Assurance testing and remote diagnoses of the display.

Ambient Light Compensation (ALC)

Changing ambient light conditions in the
radiology reading room greatly influence display
performance and the ability to detect subtle
information. To compensate for this, Barco created

the intelligent Ambient Light Compensation (ALC) system.

Barco’s ALC functionality:

• Measures the ambient luminance

• Compares the measured luminance to preset thresholds

that characterize your reading room, as defined in the AAPM
TG18 guidelines

• Notifies the QA administrator if the ambient luminance is

not within the predefined range

• Corrects the DICOM curve in the Look-Up Table in real-

time in accordance to the luminance level of the reading
environment (if preferred)

In combination with Barco’s MediCal QAWeb, ALC provides
an automatic alert functionality that warns the administrator
when the level of ambient light in the reading room is too
high.

K5906087 01.00 1107 © 2007 Barco

Technical specifications are subject to change without prior notice

Reading environment

Max illuminance

level (Lux)

Preset

illuminance

(Lux)

X-Ray

Diagnostic reading

room

10 5

CT/MR/NM reading

Room

60 35

Staff office

180 120

Clinical viewing room

250 215

ER room

300 275

OR room

400 350

Custom

TBD (<1000 Lux) TBD (<1000 Lux)

Typical ambient light levels in various reading environments