Appendix D Calibration (Using Generator Service Tools)
Revision W HF Series X-ray Generators - Service Manual
D-56 Quantum Medical Imaging, LLC
Base OD Calibration Procedure
Note: When calibrating the first Receptor/Film
Screen, set the "Offset" value to 1200, and adjust
the MASTER GAIN potentiometer on the ion
chamber until the desired target density is
obtained.
Note: If the system is equipped with "standard
type" AEC Board A11 (AY40-031S), the "Table
Gain Adj. Potentiometer" is A11R22 and the "Wall
Gain Adj. Potentiometer" is A11R23. If the sys-
tem is equipped with "Universal type" AEC Board
A11 (AY40-027S), the "Table Gain Adj. Potenti-
ometer" is A11R77 and the "Wall Gain Adj. Poten-
tiometer" is A11R79.
If the selected film/screen combination is the first one to be calibrated with
the system, perform the following steps:
1. Set the ion chamber detector selection to middle detector and ensure x-
ray tube is at correct SID. Ensure the ion chamber has been balanced.
2. Set the Optical Density to the desired target level (e.g., "650.00" as
shown in Figure D-31). To do so, set the OD range (located directly
below "Optical Density" field) for 10-1000. Enter the Optical Density
value by adjusting the slide control, or by selecting the data entry box
and typing the value using a keyboard. The value entered should be to
the hundreths decimal place.
Do not change the Target Level setting at
any time during this procedure.
3. Set the Offset value displayed on the Base OD Calibration screen (Step
2.) to "1200" by adjusting the slide control, or by selecting the data entry
box and typing the value using a keyboard. The Offset value adjustment
range is from 500 to 4000.
4. Place 5 cm of acrylic in the X-ray beam completely covering the ion cham-
ber detectors.
5. Take an exposure at the setting indicated on the Base OD Calibration
Screen (i.e., 50 kVp, 200L mA, normal density).
6. On film systems, develop the film and then measure its optical density.
On CR or DR systems, observe the density level displayed on the inte-
grated system’s workstation computer.
7. Press the Calibrate button.
8. If the density value is within acceptable range of the Target Level (on CR
or DR systems, refer to manufacturer’s specifications), press the Con-
firm button to save the setting and proceed to AEC kVp Calibration.
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.
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