Chapter 3 Calibration
HF Series X-ray Generators - Service Manual Revision W
Quantum Medical Imaging, LLC 3-57
8. If the selected film/screen combination is the first one to be cali-
brated with the system (if so, it should be combination having slow-
est speed and/or largest SID), perform the following steps:
a. Verify the AEC Ref field is set to 2000. If not, use the up and
down keys next to the AEC Ref field to set the AEC Ref value to
"2000".
b. If not already done so, set the Optical Density value to the
desired film optical density value (for example, 1.30).
c. Place 5 CM of acrylic in the X-ray beam. Take an exposure at the
setting indicated in the center display box (i.e., 50 kVp, 200L mA).
d. Develop film and measure optical density using a calibrated den-
sitometer.
e. If the system is equipped with AEC Board A11 part number
AY40-031S, proceed as follows:
i. If the measured optical density corresponds with base optical
density setting, press the Next Calibrate key to save the
setting and proceed to Reciprocity Calibration. If not, adjust
potentiometer A11R22 (if calibrating the table receptor) or
A11R23 (if calibrating the wall receptor), and repeat expo-
sure. Continue until the measured optical density equals the
base optical density setting (at least to within 5% of base
optical density setting).
ii. If the measured optical density still does not equal the Base
Optical Density setting, set A11R22 or A11R23 to mid-range,
then adjust the ion chamber’s MASTER GAIN potentiometer
until roughly the desired optical density of film is obtained.
Further fine-tuning can then be achieved by adjusting potenti-
ometer A11R22 (table) or A11R23 (wall) as described in the
previous step.
NOTE: If the measured optical density still does
not equal the Base Optical Density setting even
with the ion chamber’s MASTER GAIN potentiome-
ter set to maximum gain position, increase each
chamber detector gain and perform the "AEC MAS
Balance Verification" procedure. Repeat AEC Opti-
cal Density calibration. If the measured optical
density still does not equal the Base Optical Den-
sity setting after adjusting the MASTER GAIN and
gain of individual detectors, reduce the AEC Refer-
ence until you obtain the desired optical density.
f. If the system is equipped with AEC Board A11 part number
AY40-027S, proceed as follows:
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