Villa Rotograph EVO, Руководство по обслуживанию

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SERVICE MANUAL
Troubleshooting
Rotograph EVO (Rev. 1) 8-66
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Part of the image is enlarged while the other one is reduced
The schema described on Figure 8-6 the film obtained; it is possible
to observe that one part of the radiography is blurred and enlarged,
while the other one is reduced and seems to be on focus; the two
condiles are at the same height on the film.
Figure 8-6
Possible cause:
This effect can be due to two different causes.
In the first one, the median-sagittal plane is not
aligned with the relevant centring light beam, which
falls at the centre of the chin support.
In the second case instead, the centre of the median-
sagittal plane matched the centre of the chin support,
but the patient’s head is rotated.
In both cases, one side is closer to the film plane than the other, thus
resulting in a different magnification of the two sides; the part more
distant from the film will be more magnified while the part closer to
the film plane will result smaller. This error in positioning the patient
will result in a radiography as shown in the next drawing: the right-
most area of the image shows a bigger magnification that can be
noticed either on the teeth and on the ascending rami of the TMJ.
Remedy:
Check the positioning of the median-sagittal plane by using the
relevant centring light beam.
A more accurate check is performed using the special tool and
making a film; the dimensions measured on the obtained film must
match those reported in the paragraph 7.2.1.