22,23,24 Flashcards
In paranormic imagining ,
The receptor and x ray tube head move around the patient, in different directions.
Panoramic imaging
Extra oral technique used to examine the maxilla and mandible on a single projection
Rotation center
The pivotal point ,or axis around which the receptor and the X-ray tube head rotate.
Depending on the manufacture one of three different rotational centers are used in the panoramic x ray machines. They are…
Double center rotation
Triple center rotation
Moving center rotation
The rotation changes allow for…
The image Layer to conform to the elliptical shape of the dental arches.
The focal trough
Can be defined as three deminsional curved zone in which structures are clearly demonstrated on panoramic image.
Panoramic units may differ with regards to
The numbers of different rotation centers
The collimator used in panoramic x ray tub heads differ…
from the ones used in intra oral
The panoramic collimator is a
Lead plate with an opening in the shape of a narrow vertical slit
The tube head always rotates
Behind the patients head
The receptor always rotates
In front of the patients head
When the cassette holder is exposed to X-rays
The screens convert the x ray energy into light,which in return exposes the screen film.
Calcium tungstate screens emit
Blue light
Rare earth screens emit
Green light and require less xray exposure and are considered faster than the calcium tungstate
One intensifying screen is placed
On each side of the film and held in place when the cassette is closed.
If the tongue is not in contact with the palate during exposure a dark radiolucent shadow that obscures the spices of the maxillary teeth results.to prevent such errors…
The patient must be instructed to swallow once and hold tounge against palate during procedure.
If the patients chin is po intend up or too high
1 the hard palate and floor of the nasal cavity appear superimposed over the roots of the maxillary teeth
2 a loss of detail in the maxillary incisor region occurs.
3 the maxillary incisors appear blurred and magnified
4 * a revers smile line :( is seen in the image.
If the patients teeth are too far forward on the bite block
Anterior teeth appear skinny and out of focus
If the patients teeth are too far back on the bit block
The teeth appear fat
The images seen on the paranormic are not as sharp as the intra oral projections because of
The intensifying screen
Extra oral images are
Placed out side of he mouth and used to view large areas of the skull or the Jaws. Many are primarily used in orthodontics and oral surgery.
Extra oral projection may be used alone or in conjunction with
Intra oral projections, they aren’t also not as defined as intra oral projections.
An occlusal size ? May be used for some extra oral images
4
The occlusal film used extra orally does not
Cover as large of an area as does a screen film
