Deck 42: Extraoral Imaging

Question 1

How can a lead apron artifact be avoided during exposure of panoramic images?

A)Use a lead apron without a thyroid collar.
B)Place the lead apron high around the neck of the patient so that it does not block the x-ray beam.
C)Place the lead apron low around the neck of the patient so that it does not block the x-ray beam.
D)Both a and c are correct.

Answer 1

Both a and c are correct.

Question 2

The focal trough is an imaginary three-dimensional curved area or space,shaped like a:

A)gutter.
B)bowling pin.
C)horseshoe.
D)baseball diamond.

Answer 2

horseshoe.

Question 3

Advantages of panoramic imaging,when contrasted with intraoral imaging,include:

A)less radiation exposure.
B)no focal trough limitations.
C)lower equipment cost.
D)both a and c.

Answer 3

less radiation exposure.

Question 4

In panoramic imaging,________ around the patient.

A)the film/sensor rotates
B)the tubehead rotates
C)both the film/sensor and the tubehead rotate
D)neither the film/sensor nor the tubehead rotates

Question 5

A patient wearing earrings or glasses must remove them before a panoramic x-ray image exposure; otherwise,a _____ will appear on the image.

A)dark area
B)blurred area
C)ghost image
D)both b and c

Question 6

The quality of the panoramic view depends on:

A)how the patient's jaw is positioned within the focal trough.
B)the size of the patient's jaw.
C)how closely the patient's jaw conforms to the focal trough.
D)all of the above.

Question 7

The ______ used in the panoramic x-ray machine tubehead is a lead plate with an opening shaped like a narrow vertical slit.

A)filter
B)collimator
C)patient chair
D)bite block

Question 8

The correct position of the Frankfort plane for a diagnostically correct panoramic image is:

A)parallel to the floor
B)perpendicular to the floor
C)tipped downward
D)tipped upward

Question 9

The main components of the panoramic unit include ________,and exposure controls.

A)x-ray tubehead
B)x-ray tubehead, position-indicator device
C)x-ray tubehead, head positioner
D)position-indicator device, head positioner

Question 10

The exposure controls allow the _____ to be adjusted on the panoramic x-ray unit,to accommodate patients of different sizes.

A)exposure time
B)vertical angulation
C)horizontal angulation
D)milliamperage and kilovoltage

Question 11

Anterior teeth that appear fat are caused by the:

A)patient's teeth positioned too far forward on bite block.
B)patient's teeth positioned too far back on bite block.
C)patient not sitting or standing up straight.
D)chin positioned too low.

Question 12

A panoramic image allows the dentist to:

A)detect caries.
B)view the entire dentition and related structures in one film.
C)view all of the sinus cavities.
D)both a and b.

Question 13

The lead plate in the panoramic tubehead with an opening shaped like a narrow vertical slit is the:

A)exposure control.
B)cephalostat.
C)focal trough.
D)collimator.

Question 14

Which statement is not true of the panoramic tubehead?

A)The tubehead rotates the film behind the patient's head.
B)The tubehead rotates behind the patient's head.
C)The vertical angulation of the tubehead is not adjustable.
D)The tubehead houses the filament that produces electrons and target that produces radiographs.

Question 15

Advantages of panoramic imaging include which of the following?

A)The entire maxilla and mandible are seen on one image.
B)It is easy and quick to learn how to expose a panoramic image.
C)Patients prefer panoramic images and are exposed to less radiation.
D)All of the above are advantages of panoramic imaging.

Question 16

What new feature of the panoramic unit has allowed better resolution to show better details?

A)Cephalostat
B)Focal trough
C)Digital technology
D)Magnetic resonance

Question 17

A ghost image will appear _____ than normal and on the _____ side of the image.

A)larger; opposite
B)larger; same
C)smaller; opposite
D)smaller; same

Question 18

Which statement is not true concerning panoramic imaging?

A)Panoramic images are primarily used for locating impacted teeth, lesions in the jaw, and eruption patterns.
B)With film-based imaging, bitewings need to be taken to detect decay.
C)Digital panoramic unit can show small interproximal carious lesion, eliminating the need to take bitewing images.
D)The digital panoramic unit uses film that has to be processed.

Question 19

When the patient's jaws are outside the focal trough,the resulting images are:

A)doubled.
B)ghost images.
C)distorted.
D)too light.

Question 20

Each panoramic unit has a(n) ______ that is used to align the patient's teeth as accurately as possible.

A)head positioner
B)tubehead
C)exposure control
D)power source

Question 21

Which is not true of the cone beam computed tomography (CBCT)?

A)The software program for the CBCT unit makes it possible to see soft tissue.
B)The images can be sent over the Internet for consultation on cases.
C)The CBCT is a little difficult to learn to use and requires a lot of practice.
D)The CBCT images may be colorized on the computer.

Question 22

A dark radiolucent shadow that obscures the anterior teeth can indicate that the patient's:

A)chin was too low.
B)head was posterior to the focal trough.
C)lips were not closed on the bite-block during the exposure.
D)tongue was not in contact with the palate during the exposure.

Question 23

If the patient's chin is too high during the panoramic exposure:

A)the maxillary premolars will be blurred.
B)the floor of the nasal cavity will be superimposed over the roots of the mandibular teeth.
C)a "reverse smile line" will appear on the radiograph.
D)detail of the mandibular region will be lost.

Question 24

The part of the unit that aligns the patient's teeth as accurately as possible is the:

A)head positioner.
B)focal trough.
C)Frankfort plane.
D)tubehead.

Question 25

The CBCT is useful in helping the dentist:

A)decide the correct placement of implants.
B)with extractions of impacted teeth.
C)determine the exact location of the mandibular nerve before surgery.
D)all of the above.

Question 26

Which statement is not true regarding magnetic resonance imaging (MRI)?

A)The MRI technique is valuable in the diagnosis of temporomandibular disorders.
B)The MRI technique exposes the patient to a large amount of radiation and should only be used when no other source is available.
C)The MRI has the ability to distinguish among soft tissues, such as salivary glands.
D)MRI units are large and usually not found in dental offices.

Question 27

If the patient's teeth are not positioned in the groove of the bite-block,the teeth will appear:

A)"fat."
B)"skinny."
C)"tall."
D)"short."

Question 28

If a dark radiolucent shadow obscures the apices of the maxillary teeth,the:

A)patient's lips were not closed on the bite-block during the exposure.
B)patient's tongue was not in contact with the palate during the exposure.
C)patient's head was posterior to the focal trough.
D)patient needed to swallow.

Question 29

A grid:

A)reduces the amount of scatter radiation that reaches the patient.
B)decreases the contrast of the radiographic image.
C)decreases the film fog, increasing the contrast of the image.
D)both a and c.

Question 30

The skull view that shows the bones of the face and skull and the soft tissue profile is the ______ projection.

A)lateral cephalometric
B)posteroanterior
C)magnetic resonance
D)temporomandibular

Question 31

Computed tomography:

A)is used in dentistry primarily for diagnosing of lesions and planning implant cases.
B)uses a magnetic field, thereby not exposing the patient to x-radiation.
C)has long been used in dental radiology and the scanners are common in dental offices.
D)requires the use of film and processing.

Question 32

The cause of a panoramic image that comes out with a radiopaque cone-shaped artifact that interferes with the diagnostic information is the:

A)patient's chin was too high during the procedure.
B)patient's lead apron was incorrectly placed or a lead apron with a thyroid collar was used.
C)patient's head was posterior to the focal trough.
D)patient moved during the procedure.

Question 33

Which statement is true of a grid?

A)The grid is placed between the patient's head and the film.
B)A grid allows passage of the x-ray beam.
C)Scatter radiation is absorbed by the lead strips on the grid, reducing film fog.
D)All of the above are true.

Question 34

Skull radiography is most often used in:

A)endodontics and oral surgery.
B)oral surgery and orthodontics.
C)orthodontics and fixed prosthodontics.
D)prosthodontics and pediatric dentistry.

Question 35

If the patient's chin is positioned too low during the panoramic exposure:

A)the mandibular incisors will appear blurred.
B)the condyles will not be visible.
C)detail in the posterior apical regions will be lost.
D)both a and b.

Question 36

If the patient does not stand or sit with a straight spine:

A)the panoramic image will be blurred.
B)an "exaggerated smile line"" or curved downward smile line will appear.
C)detail of the apical regions of the teeth will be lost.
D)the cervical spine will appear as a radiopacity in the center of the film, obscuring the diagnostic information.