HF Series Generators
Calibration
CA-1036R2
28
Illustration 2-1
Automatic Exposure C ontrol
COMPARATOR
Reference
Ramp
ATP Console CPU
Microprocessor
AEC STOP
Data Bus
DAC
Adjustment
(Potentiomer)
to cut the exposure
Jumper
V out
Vref
(from Ion Chamber)
EXP ORDER
STRT DR
Ion Chamber Output
DAC Vout (Reference)
(calibration data setting)
EXP Start
EXP Stop
AEC STOP
(AEC CONTROL PCB)
AEC Function Waveform
2.6.1 PREVIOUS CHECKS
Make sure the automatic processor works correctly, and the concentration and
temperature of the solutions comply with manufacturer specifications.
Obtain a sensitometric curve to determine gamma ( γ) of the film and the s olution
quality. The procedure normally requires a sensitometer, but if it is not available
proceed as follows:
1. Make two exposures using the same kV and Film/Screen combination
(medium is recommended) but with different mAs settings, mAs(f1) and
mAs(f2).
2. Develop and measure the Density (d) of each, d(f1) and d(f2).
3. Determine gamma (γ) by the formula:
γ =
d(f2) − d(f1)
log
10
mAs(f2)
mAs
1
Gamma (γ) must be between 2 and 3, if not change or renew solutions.
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