Panoramic Radiography Flashcards
What is a panoramic dental image?
extraoral radiograph technique used to examine upper and lower jaws on a single film/image
Describe in basic terms how a panoramic image is taken
while both the receptor and tubehead rotating around the patient, a series of images are taken and then combined into a single image
List the uses of panoramic radiographs
evaluate…
-impacted teeth
-eruption patterns, growth and development (orthodontics)
-diseases, lesions, and conditions of the jaw
-extent of large lesions
-trauma and jaw fractures
What are panoramic images NOT used to evaluate?
-caries
-periodontal disease
-periapical lesions
*due to less definition and sharpness of image
What is tomography or tomo-section
radiographic technique that allows imaging of one layer or section of the body while blurring images from structures in other planes
Describe the relationship of the patient to the receptor and the tubehead
while the patient is stationary, the receptor rotates around the patient in one direction, and the tube head rotates around in the opposite direction as the receptor
What does rotational change allow?
the change in center of rotation allows the image layer to conform to elliptical shape of dental arches
What is the focal trough?
-a 3d curved zone in which structure are clearly demonstrated on a pan
-aka image layer
-structures outside of the trough are blurred or indistinct
The quality of panoramic images depends on…
positioning of patient teeth as well as their maxilla and mandible within the focal trough
*focal trough is designed for the average jaw
Real image
aka true image
correct location, sharp
Double image
mirror image (reverse)
same structure is penetrated by x-ray beam twice
Ghost image
resembles true image but located on opposite side and higher than the original
-image outside of focal plane
The vertical angulation of the pan tubehead is fixed at…
-10 degrees (beam directed slightly upward)
The sensor/film rotates _____ of the patient, while the tubehead rotates _____ the patient.
in front of; behind
Why is the exposure time fixed on panoramic imaging machines?
fixed at the time it takes the machine to make a complete rotation
What is the purpose of the collimator in panoramic imaging machines?
lead plate with opening in shape of a narrow vertical slit
-xray beam exposes receptor through vertical slit, thus producing many slivers of exposure that join to make one continuous image
another name for extraoral film is…
screen film; sensitive to xrays and light emitted by intensifying screens
*must be marked with right and left to indicate the sides of the patient face
Why is there no thyroid collar on the lead apron for pan exposure?
to prevent a radiopaque lead artifact from interfering with that location on the radiograph
What part of patient preparation can prevent ghost images?
removal of ALL jewelry, piercings, pins, metals, glasses, ortho/denture appliances
The longer side of the lead apron should be covering the front or back of the patient?
back
Why must the patient stand with their spine straight and shoulders relaxed?
to prevent superimposition of cervical spine in the anterior region of the radiograph
Frankfort plane
imaginary line passing through the top of the ear canal and bottom of eye socket
*parallel to the floor
To get the tragus-ala line to be positioned correctly, how should the patients head be positioned?
with their chin angled slightly downward
*hard palate may be imposed on apices of mx teeth if the tragus ala line and frankfort plane are not correct
How will the radiograph appear if the patient does not place their tongue to the roof of their mouth and keep it there during exposure?
a radiolucent shadow will appear over the apices of mx teeth
