Panoramic Radiography

Question 1

What is a panoramic dental image?

Answer 1

extraoral radiograph technique used to examine upper and lower jaws on a single film/image

Question 2

Describe in basic terms how a panoramic image is taken

Answer 2

while both the receptor and tubehead rotating around the patient, a series of images are taken and then combined into a single image

Question 3

List the uses of panoramic radiographs

Answer 3

evaluate…
-impacted teeth
-eruption patterns, growth and development (orthodontics)
-diseases, lesions, and conditions of the jaw
-extent of large lesions
-trauma and jaw fractures

Question 4

What are panoramic images NOT used to evaluate?

Answer 4

-caries
-periodontal disease
-periapical lesions
*due to less definition and sharpness of image

Question 5

What is tomography or tomo-section

Answer 5

radiographic technique that allows imaging of one layer or section of the body while blurring images from structures in other planes

Question 6

Describe the relationship of the patient to the receptor and the tubehead

Answer 6

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

Question 7

What does rotational change allow?

Answer 7

the change in center of rotation allows the image layer to conform to elliptical shape of dental arches

Question 8

What is the focal trough?

Answer 8

-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

Question 9

The quality of panoramic images depends on…

Answer 9

positioning of patient teeth as well as their maxilla and mandible within the focal trough
*focal trough is designed for the average jaw

Question 10

Real image

Answer 10

aka true image
correct location, sharp

Question 11

Double image

Answer 11

mirror image (reverse)
same structure is penetrated by x-ray beam twice

Question 12

Ghost image

Answer 12

resembles true image but located on opposite side and higher than the original
-image outside of focal plane

Question 13

The vertical angulation of the pan tubehead is fixed at…

Answer 13

-10 degrees (beam directed slightly upward)

Question 14

The sensor/film rotates _____ of the patient, while the tubehead rotates _____ the patient.

Answer 14

in front of; behind

Question 15

Why is the exposure time fixed on panoramic imaging machines?

Answer 15

fixed at the time it takes the machine to make a complete rotation

Question 16

What is the purpose of the collimator in panoramic imaging machines?

Answer 16

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

Question 17

another name for extraoral film is…

Answer 17

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

Question 18

Why is there no thyroid collar on the lead apron for pan exposure?

Answer 18

to prevent a radiopaque lead artifact from interfering with that location on the radiograph

Question 19

What part of patient preparation can prevent ghost images?

Answer 19

removal of ALL jewelry, piercings, pins, metals, glasses, ortho/denture appliances

Question 20

The longer side of the lead apron should be covering the front or back of the patient?

Answer 20

back

Question 21

Why must the patient stand with their spine straight and shoulders relaxed?

Answer 21

to prevent superimposition of cervical spine in the anterior region of the radiograph

Question 22

Frankfort plane

Answer 22

imaginary line passing through the top of the ear canal and bottom of eye socket
*parallel to the floor

Question 23

To get the tragus-ala line to be positioned correctly, how should the patients head be positioned?

Answer 23

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

Question 24

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?

Answer 24

a radiolucent shadow will appear over the apices of mx teeth

Question 25

List the advantages of panoramic radiography

Answer 25

-field size (entire max and mand in 1 image)
-simplicity
-patient cooperation
-minimal exposure

Question 26

List the disadvantages of panoramic imaging

Answer 26

-image quality (less sharp)
-focal trough limitations
-distortion
-equipment cost

Question 27

What causes a reverse smile error

Answer 27

chin it tipped up too much

Question 28

What causes an exaggerated smile error

Answer 28

chin tipped down too much

Question 29

What causes the error of narrowing and blunting of anterior teeth

Answer 29

patient teeth too far FORWARD on bite block

Question 30

What causes the error of widening and blurring of anterior teeth

Answer 30

patient teeth too far BACK on the biteblock

Question 31

What error causes the posterior teeth and ramus to appear magnified

Answer 31

head not centered during exposure
*use lasers to center the patients head

Question 32

The cervical vertebrae appear as a ______ _______on images where the patients spine was not straight.

Answer 32

radiopaque shadow