d. Place two pennies in the center of each margin of the light field.
One penny inside the light field.
One penny outside the light field.
e. Mark the film with the "A" and "F" markers because they will help designate
the anode and front of the table in case the collimator is inaccurate. You can then
determine which way the collimator needs adjustment. Place the lead markers and
letters as indicated below:
"A" at the anode end of the x-ray tube.
"F" marks the front of the x-ray table (see figure 4-14).
(3) The lead letters go well inside the light field in order to identify the room
number and date (see figure 4-15).
f. Make the exposure using 60 kVp at 5 mAs.
g. Process the film.
Commercially made collimator test tools can be used in lieu of pennies.
Figure 4-14. Collimator test tool with "A" and "F" markers.