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GENERAL ELECTRIC
MEDICAL SYSTEMS
AMX-ll X-RAY UNIT
1-981
SM
A0654E
14-3
Large Field Size Check
ce
г
А
initial Conditions:
ANODE
C
a
Same as Section 14-1.
|
1.
Position a loaded 14" x 17" (35.5 cm x 43.2 cm) cassette
under the collimator (17" (43.2 cm) dimension transverse
(1.016 m)
to the axis of the tube unit). Using the collimator meas-
40"
uring tape set the source-to-image distance at 40" (1.016 m).
2.
Adjust the blades to yield a field size of 14" x 17" (35.5
cm x 43.2 cm).
Place a coin on the cassette to identify
the anode front corner of the x-ray field.
& 3.
Make a 50 KVP, 1 MAS exposure and develop the film.
n (35.5 cm) 러
14"
4.
If cutoff in the transverse direction is observed, lead
22005-D20
finger spacing of the collimator should be checked.
Refer
to Chapter 4, Part |, Section 5-4.
ILLUSTRATION 4-11-43
14-4
Field Lamp Voltage Check
To meet HEW requirements, the voltage at the collimator lamp socket must be at least 19.6 VAC (RMS)
at a minimum battery voltage of 110 VDC.
This is an indirect test of illumination level.
NOTE:
Because the lamp voltage is a square rather than sine wave, the voltage measured with a Fluke
8000A Digital Meter will be greater than the true RMS value.
Lamp voltage can be measured
with a true RMS calculating digital meter such as a Weston/Schlumburger, Mode! 4445.
How-
ever, do not use an iron-vane AC
voltmeter because it will overload the lamp circuit.
.
L u .
6-32 x 1/4"
Inital Conditions:
FRONT
UNC HEX SOC.
NAMEPLATE
SET SCREWS
Same as Section 14-1.
Instrumentation:
Battery Voltage:
digital voltmeter from section 13.
1.
Remove the Blade Control Knobs and the
collimator front nameplate.
a.
Loosen two 6-32 unc x 1/4" hex soc. set screws
at the top front of the collimator frame.
b.
Tilt the nameplate forward enough to clear
the knob shafts and lift out.
REMOVE BLADE
-
CONTROL
KNOBS
ILLUSTRATION 4-11-44
4-11-35
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