THEORY GUIDE Radiography Theory
10DEC05
TG4825-1
Page
15 of 120
The following table compares the analog and digital health image capture systems.
Analog Screen/Film Systems Digital CR Systems
Uses “Rare Earth” SCREENS -
GADOLINIUM OXYSULFIDE or
LANTHANUM OXYBROMIDE.
Uses a BARIUM FLOUROHALIDE STORAGE
PHOSPHOR SCREEN.
Speed range from 100 - 1000. Screen speed:
• General Purpose (GP), 200 - 250
• High Resolution (HP), 100 - 125
• Enhanced High Resolution (EHR), 100 - 125
Film processing parameters are important
in determining the quality of the image,
for example chemical temperature and
timing.
No film processing is necessary.
It is hard to obtain the same print quality
when copies are necessary because of
variations in GENERATORS,
PROCESSORS, positions, procedures,
and conditions for developing the film.
The user can print a copy of the digital image
at any time.
Overexposing or underexposing an image
normally makes it necessary to expose
the patient to ionizing radiation again.
Exposure factors do not normally make it
necessary to expose the patient to ionizing
radiation again.
Image quality is changed by conditions in
the environment, for example temperature
or humidity.
Image quality is not changed by conditions in
the environment.
The image cannot be viewed in more
than one place at a time.
CR images can be viewed at more than one
place at the same time, in the same building or
in remote nodes on the network.
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