HF Series Generators
Calibration
CA-1036R2
39
2.6.4 kV COMPENSATION
To maintain constant AEC Optical Density regardless of the kV at which a film
is exposed, the Generator provides kV compensation. (Refer to Illustration 2-3)
Perform the following steps to determine whether or not AEC Tracking of Optical
Density must be adjusted.
1. Enter in calibration mode and verify that AEC Tracking number in E08,
E10 and E24 Memory Locations is “0”. Exit from calibration mode.
2. Enter in calibration mode selecting a Workstation configured for the Ion
Chamber to be calibrated. Enter in user mode inside calibration mode by
pressing the “Go to User Mode” button.
3. Select on the Console:
G RAD Menu: 55 kV, 200 mA Large Focus (or the first mA station for
Large Focus if 200 mA station is set for Small Focus) and 1 second
back-up time.
G AEC Menu: “Central Area”,“Density 0” and “Medium
Film/Screen”.
4. Make an exposure w ithout film in the cassette and check that the
Exposure Time is lower than 1 second. If necessary for that, change the
Copper thickness (or if needed change the mA station) and make the
exposure again. Take note of the final Copper thickness and mA station
selected for 55 kV.
5. Select 90 kV. Make an exposure without film in the cassette and check
that the Exposure Time is higher than 20 ms. If necessary for that, change
the Copper thickness (or if needed change the mA station) and make the
exposure again. Take note of the final Copper thickness and mA station
selected for 90 kV.
6. Select 110 kV. Make an exposure without film in the cassette and check
that the Exposure Time is higher than 20 ms. If necessary for that, change
the Copper thickness (or if needed change the mA station) and make the
exposure again. Take note of the final Copper thickness and mA station
selected for 110 kV.
7. Insert a cassette with the Medium Film/Screen combination used by the
customer. Make an exposure at 55 kV and 90 kV (use the final Copper
thickness and the selected mA station noted before for each kV), develop
the film and measure the Optical Density obtained with those exposures.
Check that the film variation range is the same ±0.2 of the Optical
Density (±20% of Image Gray Level / D ose Level with CR or DR)
obtained before at 70 kV (Optical Density Adjustment -- Section 2.6.3).
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