chapter 42 Extraoral Imaging

A panoramic image allows dentist to do all of the following except?

determine if a tooth is percussion sensitive

In panoramic imaging,rotated around the patient

both the image receptor and the tubehead

The focal trough is an imaginary three-dimensional curved area or space the same shape as

horseshoe

The _______used in panoramic x-ray machine tube head is a lead plate with an opening shaped like a narrow vertical slit that is used to align the patients teeth as accurately as...

Collimator

Each panoramic unit has a(n) ______ to be adjusted on the panoramic x-ray unit, to accommodate

head positioner

The exposure controls allow the patients of different sizes?

Milliamperage and kilovoltage

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

Ghost image

A ghost image will appear?

larger;opposite

To avoid a lead apron artifact on a panoramic radiograph

Use a lead apron without a thyroid collar, and place the lead apron low around the neck of the patient so that it does not block the x-ray beam.

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

parallel to the floor

Anterior teeth that appear fat are caused by ____________.

the patient's teeth positioned too far back in the bite block

Advantages of panoramic imaging include which of the following?

the entire maxilla and mandible are seen on one image, it is East and quick to learn how to expose a panoramic image, patients prefer panoramic images and are exposed to less radiation (all of the above)

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

less radiation exposure and lower equipment cost (both a and c)

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

digital technology

All of the following statements about panoramic imaging are true accept?

The digital panoramic unit uses film that has to be processed

The quality of the panoramic view depends on?

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

blurred

The main components of the panoramic unit include the panoramic x-ray tube head, the head positioner, and?

exposure control

Which of the following is a device used to position the film and patient for an extraoral panoramic image?

Cephalostat

All the following statements about the panoramic tubehead are true except the?

Tubehead rotates the film behind the patients head

The purpose of the head positioner is to position the patient correctly in the?

Focal trough

A radiopaque, cone-shaped artifact on a panoramic image that interferes with the diagnostic information is caused by the:

patient's lead apron was incorrectly placed or a lead apron with a thyroid collar was used

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

tongue was not in contact with the palate during the exposure

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

patient's tongue was not in contact with the palate during the exposure

When a patient's chin is too high during the panoramic exposure

reverse smile line will appear on radiographs

When a patient's chin position too low during the panoramic exposure?

the mandibular incisors will appear blurred and the condyles will not be visible (both a and b)

When a patient teeth are not positioned in the groove of the bite-block and are too far forward, the teeth will appear

Skinny

When a patient does not stand or sit with a straight spine?

the cervical spine will appear as a radiopacity in the center of the film, obscuring the diagnostic information

All of the following statements about cone beam computed tomograph are true except the?

CBCT is a little difficult to learn to use and requires a lot of practice

The CBCT is useful in helping the dentist?

decide the correct placement of implants; with extractions of impacted teeth; and determine the exact location of the mandibular nerve before surgery (do all of above)

A grid?

decreases the film fog, increasing the contrast of the image

Which statement is true of a grid?

The grid is placed between the patients head and the film, a grid allows passage of the x-ray beam, scatter radiation is absorbed by the lead strips on the grid,reducing film fog (all of the above are true)

Skull radiography is most often used in:

oral surgery and orthodontics

The skull view that shows the frontal and ethmoid sinuses, the orbits, and the nasal cavities is the projections?

posteroanterior

All of the following statements regarding magnetic resonance imaging are true except the MRI

Technique exposes the patient to a large amount of radiation and should only be used when no other source is available

computer tomography

Is used in dentistry primarily for diagnosing lesions and planning implant cases