Photometry The science of the response of the human eye to
light The basic unit of photometry is the lumen (lm).
Slide 4
Illuminance describes the intensity of light incident on a
surface Luminance intensity is a property of the source of light,
such as a viewbox or a digital display device
Active matrix liquid crystal displays are superior to cathode
ray tube displays. LCD design gives out more light, reduces ambient
light Better contrast resolution Less noise Less maintenance
Slide 9
Crystals can be aligned by an external electric field
Slide 10
Plasma Display The plasma displays are made up of many small
fluorescent lights that are illuminated to form the color of the
image.
Slide 11
Pixel A pixel is an individual controllable set of dot triads.
A dot triad is a grouping of one red dot, one green dot, and one
blue dot. The number of pixels on a display is known as its
resolution.
Slide 12
Resolution The more pixels in an image, the higher the
resolution of the image and the more information that can be
displayed.
Slide 13
Pixels are arranged in a matrix
Slide 14
Dot pitch Dot pitch is the measurement of how close the dots
are located to one another within a pixel
Slide 15
Spatial Resolution improves with the use of higher- megapixel
digital display devices A 1-megapixel display will have a
10001000-pixel arrangement. A high- resolution monitor will have a
5- megapixel display, or a 20002500- pixel arrangement
Slide 16
Refresh rate The refresh rate is the measure of how fast the
monitor rewrites the screen or the number of times that the image
is redrawn on the display each second. The refresh rate helps to
control the flicker seen by the user; the higher the refresh rate,
the less flicker.
Slide 17
Viewable area The viewable area is measured diagonally from one
corner of the display to the opposite corner.
Slide 18
Cosine Law Is important when one is describing the luminous
intensity of a digital display device. When a monitor is viewed
straight on, the luminous intensity is maximum. When a monitor is
viewed from an angle, the contrast and the luminous intensity are
reduced.
Slide 19
When a digital display device is viewed from the side,
illumination and image contrast are reduced.
Slide 20
LCD Disadvantage The principal disadvantage of an AMLCD is the
angular dependence of viewing Ergonomic design of digital
workstations is critical
Slide 21
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Transmission of Images PACS - Picture Archiving &
Communications System DICOM - Digital Images & Communication in
Medicine TELERADIOGRAPHY -Remote Transmission of Images
Slide 24
PACS Internet VPN Digital Images Archive Database and Workflow
Engine Workstations Remote Workstations Remote Facilities
Slide 25
PACS/HIS/RIS/X-ray System HIS = Hospital information system RIS
= Radiology information system X-ray machine patient folder
Slide 26
Archive Servers An archive server is the file room of the
PACS
Slide 27
PACS Common Functions Navigation functions are used to move
through images, studies, and patients. The worklist is used to
navigate through patients. Most worklists are customizable for the
user. One doctor or technologist may want to see only CT studies or
all neurologic studies done that day regardless of the modality.
Most modern PACS software conforms to the Windows look and
feel.
Slide 28
Questions? "The pessimist sees difficulty in every opportunity.
The optimist sees the opportunity in every difficulty." Winston
Churchill