AGFA DX-D 400 User Manual page 138

DX-D 400
User Manual
6.2 AUTOMATIC EXPOSURE CONTROL (AEC)
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Note
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Automatic Exposure Control (AEC) produces consistent film density with
excellent contrast regardless of the radiographic technique selected. The AEC
module comprises the controls for the selection of the Exposure Detector Fields
(Ion Chamber), the Film/Screen Combination, Film Density Compensation and
AEC Reset.
The AEC mode is selected by pressing any of the three AEC Field push-buttons.
To exit the AEC mode, press all the illuminated AEC Field push-buttons until
none are lit.
In AEC mode the back-up time (or back-up mAs) MUST BE SET MANUALLY
by the operator using the Console controls.
The value of the back-up time (or mAs) must be set at a greater
value than the previously considered for the exposure time (or
mAs). A value above 50% of the considered value is the
recommended. Very extreme values of back-up time (or mAs)
should be avoided to prevent patient from excessive exposure
when a control error is produced.
FIELD SELECTION: Each push-button indicates its related physical location
of the selected field in the AEC Exposure Detector, and it may be selected or
deselected by pressing it. Any combination of fields can be selected and the
push-buttons illuminate when active.
FILM / SCREEN COMBINATION:
adjustment of the mAs in relation to a programmed Film / Screen combination
that may be in use slow, medium, or fast respectively (200, 400, 800). Each time
a Film / Screen push-button is selected (illuminated), the others are
automatically deselected.
DENSITY: These push-buttons are used to adjust the radiographic film density.
Normal film density (0) is the automatic default value when AEC is selected.
Film density can be proportionally increased or decreased in steps. The
variation percentage density between steps can be changed during the
equipment calibration by the engineer according to customer preferences (the
percentage by default is 25%).
Each of these push-buttons allows
0232F EN 20191213