4-23. PREVENTIVE MAINTENANCE
Perform the collimator test routinely at two-month intervals and any time service
work is done on the beam limitation system. This includes collimator bulb replacement.
4-24. CORRECTIVE MAINTENANCE
Call the service representative or engineer to adjust the collimator when the test
results show that the x-ray field exceeds the proper location by more than one penny.
Section V. AUTOMATIC EXPOSURE TIMER (AET) QUALITY CONTROL TEST
4-25. PURPOSE
The purpose of the following test procedures is to ensure that the AET control
system functions properly. Performing quality control tests on the AET (phototiming)
system is a time-consuming and detailed project. There are six areas that must be
tested.
4-26. EQUIPMENT/MATERIAL
a. Evaluation phantom (pieces of Plexiglas).
b. Direct readout dosimeter (digital timer).
c. Ringstand and clamp.
d. Densitometer.
e. Lead number for test film identification.
f. Two sheets of 1/8-inch lead, 11 x 14 inches.
g. Cassettes with the same screen speed and film from same box.
h. Forms for recording information.
NOTE:
The following procedure should be used for each area with minor alterations
for the area of interest.
4-27. PROCEDURE
a. Set the radiographic equipment in the phototimer mode.
MD0062
4-20