THEORY GUIDE Imaging Sequence
10DEC05
TG4825-1
Page
83 of 120
5 At the same time, the SCREEN moves vertically. This vertical motion is the slow scan
direction.
Both motions are determined by calibration data for the given SCREEN size. The MSC
BOARD A1 controls the slow scan motion through the SLOW SCAN CONTROLLER
BOARD A6. The DIGITIZER BOARD A3 controls the fast scan motion through the
GALVO BOARD A4.
Obtaining the Image Data
1 The red laser beam scans across the PHOSPHOR SCREEN in the fast scan direction.
When it hits the PHOSPHOR charged by the X-ray exposure, it causes the PHOSPHOR
to emit blue light. The brightness of the blue light is proportional to the strength of the X-
(1 of 2)
PMT
PHOSPHOR SCREEN
BLUE FILTER
LIGHT COLLECTOR
red laser light
signal
analog
H194_5009GC
blue light
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