Villa Rotograph EVO, Руководство по обслуживанию

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SERVICE MANUAL
Troubleshooting
(Rev. 1) Rotograph EVO 8-75
8.5.4. Incorrect film contrast and density
•
Images too clear
Normally this indicates that the exposure parameters are too low
with respect to the patient size. Another possible cause is a wrong
film development process, especially if a manual developer is used.
Another possibility is the misalignment of the X-ray beam with
respect to the alignement of the two collimators.
Remedy:
–
Increase the exposure parameters
–
Check the development process (liquids, temperatures, duration,
etc.)
–
Check that the panoramic cassette holder is fully closed in
panoramic position (check that it is really fully pushed against
the mechanical stop)
–
Check that the X-ray beam falls completely on the secondary slit.
This check must be performed removing the cover of the
secondary slit and, using a scintillator screen placed after the
slit, checking that the X-ray beam, normally smaller than the slit
itself, falls completely onto it, leaving a small gap between the
upper and lower border.
If the X-ray beam is not correctly centered, move, the tubehead,
shifting the beam sligtly on the right; if the X-ray is too much
shifted on the left of the aperture, or slightly on the left if the
X-ray is too much shifted on the right of the aperture.
To move the tubehead use the holes where the fixing screws are
placed (see Figure 8-5, items A, B,C, D).
Repeat the exposure with the scintillator screen placed before the
slit, leaving a part of the slit non covered by the screen. Check
that the beam falls completely on the slit. Repeat the above check
covering the other part of the slit.
NOTE:
If the X-ray beam must be shifted right, the tubehead must be
moved to the left and vice-versa.
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