It may be necessary to alter the technique factors to obtain an image that has
a density in the range of 1.0 to 1.5 in the areas of the aperture image.
k. Make the tomographic exposure.
Process the test film.
m. Repeat the above exposure for other tomographic motions, exposure angles,
and sweep speed.
6-16. EVALUATION AND INTERPRETATION
a. Place the test films on the illuminator.
b. Compare the density on the film.
(1) The tomographic image of the hole in the aperture reproduces the
trajectory of the x-ray tube during the exposure.
A non-uniform image density indicates a mechanical problem in the drive
The maximum variation you can expect in the density should not be greater
than three. Use a densitometer to read the densities.
c. Be aware that there are different density patterns for different machines.
For a single phase machine, evaluate:
(a) A series of overlapping dots.
You can expect a series of overlapping dots and a pulsating waveform
because of the pulsating nature of the associated high voltage waveform.
For a linear system, evaluate the tube motion:
(a) The uniform density.
(b) A straight-line pattern, not wobbly.