4-38. BACKUP TIMER TEST
a. Reset the phantom, machine factors, and AET used in the reproducibility test
(see figure 4-31).
b. Position the 1/8-inch ll- x 14-inch lead beam stop on top of the phantom to
block sensitive areas of AET. The beam will not penetrate the lead (see figure 4-32).
c. Make the exposure.
d. Record the measured time on the appropriate section of the form.
Figure 4-31. Reset to reproducibility test set up preparing
to place lead blocker over the dosimeter.