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
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
a. Evaluation phantom (pieces of Plexiglas).
b. Direct readout dosimeter (digital timer).
c. Ringstand and clamp.
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.
The following procedure should be used for each area with minor alterations
for the area of interest.
a. Set the radiographic equipment in the phototimer mode.