Appendix D Calibration (Using Generator Service Tools)
Revision W HF Series X-ray Generators - Service Manual
D-50 Quantum Medical Imaging, LLC
AEC MAS Balance Verification
The generator AEC mAs balance was pre-calibrated at the factory. However,
verification of AEC mAs balance assures AEC calibration accuracy. When bal-
anced, the mAs at the specified exposures will be approximately the same
(±6%). This procedure only needs to be performed once prior to AEC cali-
bration of the film/screen combination(s) used with the system. Proceed as
follows:
1. If not already done so, connect a kVp bleeder tank in series between
tube and High-Voltage (H.V.) Transformer A17. If using a mAs meter,
connect the mAs meter between pins A17P1-9 and A17P1-10 on H.V.
Transformer A17. This connection is made by removing the two green/
yellow wires connecting A17P1-9 and A17P1-10 to the ground stud on
top of the H.V. Transformer (see Figure D-21) and connecting the
removed wires to the mAs meter. (Note: These wires must be re-con-
nected when finished calibration.)
2. Place 20 cm of acrylic in the X-ray beam. (Where practical, adjust acrylic
thickness to obtain approximately 100 millisecond exposures.)
3. If calibrating a" level" type ion chamber, ensure all three ion chamber
detectors are selected.
4. Press the Manual/AEC Mode button on the operator control panel and
select enter AEC mode.
5. Set the operator control panel for 110 kVp (100 kVp if calibrating a "level"
type (Siemens) ion chamber - requires AY40-027S AEC board), 75S mA
and take an exposure.
6. On the Dynalyzer Digital Display or mAs meter, note the measured mAs
value.
7. Set the operator control panel for 110 kVp (100 kVp if calibrating a "level"
type (Siemens) ion chamber - requires AY40-027S AEC board) and the
highest available mA station. Take an exposure.
8. On the Dynalyzer Digital Display or mAs meter, note the measured mAs
value.
9. The mAs values noted must be within ±5%. If not, adjustment of the
dV/dt potentiometer on AEC Board A11 is necessary:
• If the generator is equipped with "standard" type AEC (i.e., AEC
Board A11 is part number AY40-031S), adjust potentiometer A11R12
to increase or decrease the mAs value.
To Next Page
Loading...
Need help?
General
