January 20- Extra Oral Techniques Flashcards
What are some ways Panorramic Images are used in a Clinical Setting
• Fractures, wisdom tooth assessment, lesions, eruption and development, retained teeth/root tips, TMJ, developmental anomalies
![](https://s3.amazonaws.com/brainscape-prod/system/cm/130/259/872/a_image_thumb.png?1659447615)
What are the different types of Panoramic image receptors?
- Film and rare-earth intensifying screens cassettes
- PSP plate cassettes
- Solid state sensor cassettes designed to fit into
existing equipment
• Specially designed solid state sensors
How does a Panoramic X-ray machine work (Very Simply)
The X-ray Tube and receptor rotate around the persons head at the same rate in a counterclockwise motion. As the X-ray passes through the structures they are projected onto the the screen/receptor producing a panoramic image.
![](https://s3.amazonaws.com/brainscape-prod/system/cm/130/261/959/a_image_thumb.png?1659447616)
What is the Focal Trough?
- This is a 3D curved zone where the structures lying within the zone are well defined on the final pan image.
- Roughly a parabolic shape designed to conform to the shape of the dental arches in the majority of the population
- Laser lights aid the operator in aligning the patients dentition optimally in the focal trough
- Objects outside the focal trough are blurred, magnified and distorted
![](https://s3.amazonaws.com/brainscape-prod/system/cm/130/262/738/a_image_thumb.png?1659447617)
Where should the dental arches be located in regards to the focal trough?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/130/262/861/q_image_thumb.png?1659504932)
• The key to taking a good pan, is
to get the patients dental
arches as close to the middle
part of the focal trough
(darkest part) as possible.
• If structures are not in the
middle of the layer they appear
distorted.
![](https://s3.amazonaws.com/brainscape-prod/system/cm/130/262/861/a_image_thumb.png?1659447617)
What happens when structures are outside the focal trough?
The edge of the layer (focal trough) is like a “cliff” where structures “fall off-out” and disappear from the image.
![](https://s3.amazonaws.com/brainscape-prod/system/cm/130/263/370/a_image_thumb.png?1659447617)
How do you correctly position a patient to ensure their dental arch lies within the Focal Trough?
Orient the patient so that their mandibular incisors are within the notch in the Pan machines “alignment stick”
![](https://s3.amazonaws.com/brainscape-prod/system/cm/130/263/591/a_image_thumb.png?1659447618)
What happens when a patients dental archs are aligned
A. at inner part of the focal trough
B. at the outer part of the focal trough
![](https://s3.amazonaws.com/brainscape-prod/system/cm/130/264/367/q_image_thumb.png?1659504933)
![](https://s3.amazonaws.com/brainscape-prod/system/cm/130/264/367/a_image_thumb.png?1659447619)
What is the common Vertical Angulation of the X-ray in Pan X-ray machines. And what effect does this angulation have on the images produced.
the common vertical angulation is 8 degrees to the horizonal, This angulation causes structures IN FRONT of the rotational center to appear HIGHER and structures BEHIND to appear Lower
![](https://s3.amazonaws.com/brainscape-prod/system/cm/130/264/556/a_image_thumb.png?1659447620)
What effect does Verticle Angulation have on resultant Pan radiographs?
Verticle angulation can cause misrepresentation of the distances between structures
ie: the distance between the apex of the root and the mandubular canal
![](https://s3.amazonaws.com/brainscape-prod/system/cm/130/266/639/a_image_thumb.png?1659447620)
In a Pan radiograph what is a Single Real Image? And when are they formed?
- single real images result when a structure is located in front of the centre of rotation (i.e. between the image receptor and the rotation centre) and is intercepted only once by the x-ray beam
- The majority of the images seen on a panoramic image
are this type e.g. maxillary sinus, floor of orbit, soft tissue
of nose etc
![](https://s3.amazonaws.com/brainscape-prod/system/cm/130/267/211/a_image_thumb.png?1659447620)
In Panoramic radiographs what is a Double Real Image? And when are they formed?
Double Real Images are produced if a structure is located in front of the centre of rotation and is intercepted twice by the x-ray beam.
- These images are produced by structures in the posterior midline such as the hard and soft palate, hyoid bone, epiglottis and the cervical spine that fall into a diamond shaped zone produced by the the movement pattern of the x-ray beam.
- One image is the exact mirror image of the other
![](https://s3.amazonaws.com/brainscape-prod/system/cm/130/267/380/a_image_thumb.png?1659447621)
in Panoramic Radiographs what is a Ghost Image and how are they formed?
- Ghost images are formed when the anatomical structure is located behind the rotation centre of the x-ray beam. i.e. they are between the x-ray source and the rotation centre.
- Ghost images are not mirror images, appear on the opposite side, are more blurred, larger and superior than the real counterpart.
- These usually result from external objects such as earrings and necklaces, but can also occur with dense anatomical structures that are in the midline such as the angle of the mandible, the hard palate and the cervical vertebrae.
![](https://s3.amazonaws.com/brainscape-prod/system/cm/130/267/501/a_image_thumb.png?1659447621)
What is this an example of?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/130/267/818/q_image_thumb.png?1659504935)
This is an example of an artifact (earrings) GHOST IMAGE.
Note how the earrings are distorted and where they are projected.
what has caused this misrepresentation in the panoramic image?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/130/268/581/q_image_thumb.png?1659504936)
Verticle Angulation of the X-ray beam