Chapter 3 Calibration
Revision W HF Series X-ray Generators - Service Manual
3-58 Quantum Medical Imaging, LLC
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 A11R77 (if calibrating the table receptor) or
A11R79 (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 A11R77 or A11R79 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 A11R77 (table) or A11R79 (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 potentiom-
eter 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 Ref-
erence until you obtain the desired optical den-
sity.
9. If the selected film/screen combination is not the first one to be cali-
brated with the system, perform the following steps:
a. Using the up and down keys next to the Optical Density field,
set the optical density value to the desired film optical density
value (for example, 1.30). This is referred to as the "base optical
density" for this film/screen combination.
b. 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).
c. Develop film and measure optical density using a calibrated den-
sitometer.
d. 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 film density is too low,
press the AEC Ref up arrow key and increase AEC Ref value,
then repeat exposure. If density is too high, press the AEC Ref
down arrow key and decrease AEC Ref value, then repeat expo-
NOTE
The series of
AEC optical
density
measurements
should be
repeated as
many times as
required until
optical density
is sufficiently
accurate to
meet
regulatory and
facility
requirements.
To Next Page
Loading...
Need help?
General
