Radiography Ch 22 To 30

Question 1

For what do we use the extraoral projection.

Answer 1

To evaluate large areas of the skull and jaws
• To evaluate growth and development
• To evaluate impacted teeth
• To detect diseases, lesions, and conditions of the jaws
• To examine the extent of large lesions
• To evaluate trauma
• To evaluate the temporomandibular joint area

Question 2

In which rare cases do we use extraoral projection.

Answer 2

because the patient has swelling or discomfort and is unable to toler- ate the placement of intraoral receptors. Extraoral pro- jections may be used alone or in conjunction with intraoral projections

Question 3

What type of x-ray unit do we use in extra oral PROJection?

Answer 3

A standard intraoral x-ray machine may be used for a variety of extraoral images (e.g., transcranial and lateral jaw projections).

Question 4

Which type of film do we use For extraoral exposure.

Answer 4

When a film is used for extraoral exposures, a screen film is placed in a cassette with intensifying screens. The screen film is sensitive to the light emitted from intensifying screens

Question 5

Which are the most often sizes for extraoral receptors?

Answer 5

the sizes most often used are5×7inchand8×10inch.
An occlusal receptor (size 4) may be used for some extra- oral images (e.g., lateral jaw or transcranial projection).

Question 6

What is an intensifying screen?

Answer 6

is a device that converts x-ray energy into visible light; the light, in turn, exposes the screen film. calcium tungstate screens emit blue light, and rare earth screens emit green light.

Question 7

What is the purpose of a cassette.

Answer 7

hold the receptor in tight contact with the intensifying screen and to protect the recep- tor from exposure to light. Extraoral cassettes, with the exception of some panoramic cassettes, are rigid and are constructed of metal and plastic.

Question 8

What is a grid?

Answer 8

is a device used to reduce the amount of scatter radia- tion that reaches an extraoral film during exposure. Scatter radiation causes film fog and reduces contrast. A grid can be used to decrease film fog and increase the contrast of the image.

Question 9

When is lateral imaging used?

Answer 9

is used to examine the posterior region of the mandible and is valuable for use in children, in patients with limited jaw opening due to a fracture or swelling, and in patients who have difficulty stabilizing or tolerating intra- oral receptor placement

Question 10

Which are the 2 techniques used with lateral jaw imaging?

Answer 10

Body of mandible and Ramus of mandible

Question 11

What is the purpose of the lateral jaw projection-body of mandible?

Answer 11

to evaluate impacted teeth, fractures, and lesions located in the body of mandible.

Question 12

What is an Extraoral image?

Answer 12

one that is placed outside the mouth during x-ray exposure.

Question 13

What is the purpose of the ramus of mandible?

Answer 13

is to evaluate impacted third molars, large lesions, and fractures that extend into the ramus of the mandible. This projection demonstrates a view of the ramus from the angle of the mandible to the condyle

Question 14

What is skull imaging used for?

Answer 14

is used to examine the bones of the face and skull and is most often used in oral surgery and orthodontics. Although some skull projections can be exposed using a stan- dard intraoral x-ray machine, most require the use of an extraoral unit and a cephalostat.

Question 15

Which type of exposures can we take to get a clear view of the skull?

Answer 15

Lateral cephalometric projection
• Posteroanterior projection
• Waters projection
• Submentovertex projection
• Reverse Towne projection

Question 16

What is the purpose of the lateral cephalometric projection?

Answer 16

to evaluate facial growth and development, trauma, and disease and developmental abnormalities. This projec- tion demonstrates the bones of the face and skull as well as the soft tissue profile of the face

Question 17

Wha is the purpose of the posteri anterior projection?

Answer 17

is to evaluate facial growth and development, trauma, and disease and developmental abnormalities. This projection also demonstrates the frontal and ethmoid sinuses, the orbits, and the nasal cavity

Question 18

What is the purpose of the waters projection?

Answer 18

evaluate the maxillary sinus area. This projection also dem- onstrates the frontal and ethmoid sinuses, the orbits, and the nasal cavity

Question 19

What is the purpose of a submentovertex projection?

Answer 19

to identify the position of the condyles, demonstrate the base of the skull, and evaluate fractures of the zygomatic arch. This projection also demonstrates the sphenoid and ethmoid sinuses and the lateral wall of the maxillary sinus

Question 20

What is the purpose of the reverse town projection?

Answer 20

To identify fractures of the condylar neck and ramus area

Question 21

What is the temporomandibular joint?

Answer 21

Is the jaw joint. As the term temporomandibular indicates, this joint includes the temporal bone and the mandible. The glenoid fossa and the articular eminence of the temporal bone, the condyle of the mandible, and the articular disc between the bones make up the TMJ area.

Question 22

What can be seen in temporomandibular imaging?

Answer 22

to show bone and the relationship of the joint components. For example, changes in bone (e.g., erosions, bony deposits) can be seen on TMJ images.

Question 23

Which techniques can we in TMJ imaging?

Answer 23

Transcranial projection, Temporomandibular joint tomography

Question 24

What is the purpose of the transcranial projection?

Answer 24

evaluate the superior surface of the condyle and the articular eminence, This projection can also be used to evaluate movement of the condyle when the mouth is opened and to compare the joint spaces (right versus left).

Question 25

What is the purpose of the TMJ technique?

Answer 25

used to examine the TMJ. Tomography, is a technique used to show structures located within a selected plane of tissue while blurring structures outside the selected plane. In TMJ tomography, this is accomplished by moving the receptor and x-ray tubehead in opposite direc- tions around a fixed rotation point.