c. Place the cassette on the x-ray table.
d. Calculate the exposure to produce a density of approximately 0.5 (1 mAs, 45
kVp, 40" SID, rare earth; 45 kVp, 2.5 mAs, 40" SID hi plus).
e. Center the x-ray tube to the cassette.
f. Make the exposure.
g. Return the cassette to the darkroom.
h. Turn off all safelights and white lights.
i. Remove the film from the cassette.
j. Place the film on the workbench in the safelight area.
k. Cover one-half of film with opaque material (such as cardboard) and keep it
covered throughout the entire test.
Place another opaque sheet (cardboard) on top of the entire film.
m. Uncover one-fourth of the film.
n. Expose the film to the safelight for 30 seconds.
o. Slide the cardboard down on the film and expose another quarter of the film.
p. Expose the film for 30 seconds more to the safelight.
q. Repeat steps o and p until the last quarter of the film has been exposed for 30
r. Process the film.
Repeat the above procedure for all the loading benches and feed trays.
7-15. EVALUATION AND INTERPRETATION
a. Place the film on the illuminator.
b. Compare, visually, if the borders between each area were covered with the
strip of opaque material.
c. Use the densitometer to determine the difference of densities.