Ch 42 Quiz ExtraOral Imaging

A grid

decreases the film fog, increasing the contrast of the image.

Computed tomography

is used in dentistry primarily for diagnosing lesions and planning implant cases.

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

larger; opposite

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 tomography (CBCT) are true except the

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

All of the following statements about panoramic imaging are true except

the digital panoramic unit uses film that has to be processed.

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

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

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

a "reverse smile line" will appear on the radiograph.

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

tubehead rotates the film behind the patient's head.

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

lips were not closed on the bite-block during the exposure.

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

head positioner

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

skinny.

The quality of the panoramic view depends on

how the patient's jaw is positioned within the focal trough.

the size of the patient's jaw.

how closely the patient's jaw conforms to the focal trough.

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

collimator

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

focal trough.

All of the following statements regarding magnetic resonance imaging (MRI) 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.

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

less radiation exposure.

In panoramic imaging, _____ rotate(s) around the patient.

both the image receptor and the tubehead

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.

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

milliamperage and kilovoltage

Skull radiography is most often used in

oral surgery and orthodontics.

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

Cephalostat

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

blurred.

The CBCT is useful in helping the dentist

decide the correct placement of implants.

with extractions of impacted teeth.

determine the exact location of the mandibular nerve before surgery.

Do all of the above.

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

determine if a tooth is percussion sensitive.

Advantages of panoramic imaging include which of the following?

The entire maxilla and mandible are seen on one image.

It is easy and quick to learn how to expose a panoramic image.

Patients prefer panoramic images and are exposed to less radiation.

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

the mandibular incisors will appear blurred.

the condyles will not be visible.

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

exposure controls.

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

Digital technology

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

horseshoe.

The skull view that shows the frontal and ethmoid sinuses, the orbits, and the nasal cavities is the _____ projection.

posteroanterior

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

parallel to the floor.

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

Which statement is true of a grid?

The grid is placed between the patient's 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.