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Radiology Exam 5 > Chapter 23 > Flashcards

Chapter 23 Flashcards

1
Q

What is the purpose of Extraoral-Radiographs?

A
  • examine large areas of jaw or skull -study growth and development -detect fractures and evaluate trauma -detect pathologic lesions/diseases -detect and evaluate impacted teeth -evaluate TMJ -substituted for intraoral when pt. cannot open mouth
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2
Q

What type of extraoral radiograph do general dentist use?

A

Panorex used frequently

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3
Q

What type of extra oral radiographs do orthodontist use?

A

-Facial Profile Radiographs -Cephalometric Headplates

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4
Q

What do Orthodontist use extra oral films for?

A

for recording, measuring and comparing changes in growth and development.

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5
Q

What types of extra oral films do Prosthodontist use?

A

-Facial Profiles -CT Scans

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6
Q

What type of extra oral films do Oral surgeons use?

A

Almost any

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7
Q

Screen Film

A

is used in conjunction with a pair of intensifying screens housed inside a light-tight cassette. The screen film is loaded into the cassette in the darkroom that is safe for EXTRAORAL film

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8
Q

What do you need to make sure of when loading the film?

A

-Removes from box with clean, dry hands.

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9
Q

What do gloves do when using them to load film?

A

Increase chances of static electricity on the film.

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10
Q

What is an artifact?

A

anything on the film other than anatomy that does not contribute to diagnosis.

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11
Q

How do you properly handle extraoral film?

A

-by the edges only -with clean, dry hands and no gloves (gloves also have powder) -do not slide film across the intensifying screens (again makes static electricity) -Use 1 film only (unless you have special film made for taking 2) -BE SURE BOX IS CLOSED BEFORE TURNING ON LIGHT OR OPENING DOOR TO THE DARKROOM

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12
Q

Crystals of Salts

A

Calcium tungstate, barium strontium sulfate or rare earth phosphors will fluoresce and emit energy in the form of blue or green light when they absorb x-rays in the varied intensity of the x-ray passing through the object.

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13
Q

Crystals of Salts

A

The x-rays strike the screens causing visible light (fluorescent light) to intensify and strike the film causing a latent image to be formed.

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14
Q

Rare Earth Screens

A

Emit green light when energized by x-rays and must be paired with a green-light sensitive film.

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15
Q

Calcium Tungstate Screens

A

Emit blue to violet fluorescent light and must be paired with blue-light sensitive film.

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16
Q

When you switch or pair up the films incorrectly, what will you get?

A

An Undiagnostic Film

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17
Q

What do intensifying screens do?

A

Reduce radiation but also reduce sharpness dependent upon various situations.

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18
Q

The Larger the crystals

A

The less radiation is required but there is less sharpness.

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19
Q

The thicker the emulsion

A

The faster the speed of the screen, less radiation and less sharp.

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20
Q

Rare Earth Screens

A

Produce a latent image on the film with less radiation.

21
Q

Why do you want to hold the intensifying screen in close contact with the film?

A

protecting all from light exposure

22
Q

Rigid Cassettes

A

usually 5x7 inches and have a front and back joined with a hinge. The front cover is fabricated out of plastic to allow x-rays to pass. The back is heavy metal to absorb the remnant x-rays (the side away from the patient). Rigid cassettes can be ruined by dropping.

23
Q

Flexible Cassette

A

Sleeve usually are 5x6x12 inches with snaps or velcro to fasten plastic. Very easy to tear if handled roughly.

24
Q

What are GRIDS?

A

–sometimes used to absorb scatter radiation –is a mechanical devise composed of thin strips of lead alternating with a RL material usually plastic

25
Q

Where are Grids placed?

A

–are placed between the patient and film in order to absorb scatter radiation and redue film fog to improve image contrast.

26
Q

What do Grids require?

A

increasing radiation dose (usually double) so it is used for assessing a tumor but not in assessing normal growth, etc.

27
Q

Extraoral film does not have a dot do it is hard to determine what?

A

front and back. “R” and “L” is used to distinguish this.

28
Q

What are the 7 Projections?

A
  1. Lateral Jaw Radiograph aka Mandibular Oblique Lateral Projection
  2. Lateral Cephalometric Radiograph
  3. Posteroanterior Cephalometric Radiograph aka PA Projection (back to front)
  4. Waters Radiograph (Sinus Projection)
  5. Reverse-Towne Radiograph (Open Mouth Projection)
  6. Submentovertex Radiograph (Base Projection)
  7. Transcranial Radiograph (TMJ Projection)
29
Q

Lateral Jaw Radiograph aka Mandibular Oblique Lateral Projection

A

1.Most commonly taken 2.Can be taken with conventional dental office machine 3.Has been largely replaced with panoramics 4.Has greater detail in the imaging 5.Its purpose is to examine the posterior region of the mandible 6.Great for children or when patient is unable to open 7.Sees fractures and swelling

30
Q

How is the Lateral Jaw Film placed?

A

cassette is positioned flat against the cheek and is centered over the mandibular 1st molar area. The front edge of the cassette should protrude slightly beyond the tip of the nose and chin. The patient may help hold by keeping thumb on the rim.

31
Q

How is the Head placed during a Lateral Jaw X-ray?

A

-Tilted 10-20 degrees towards side to be examined and the chin is protruded. -Central Beam directed toward 1st molars from a point underneath the opposite side of the mandible -Reveals molars, premolars, ramus and incisors but can vary to focus on one aspect more than others.

32
Q

Lateral Cephalometric Radiograph

A

May either be a lateral skull projection or a frontal projection (posteroanterior) –Cephalometric means to measure the head. A cephalometer is a device used to standardize the placement of the head during exposure for a series of identically angled exposures. Cephalostats stabilize the head parallel to the film and at right angles to the direction of the beam of radiation.

33
Q

What is the purpose of the Lateral Cephalometric Radiograph?

A

To evaluate growth and development, trauma, pathology.

34
Q

What size film is used for Lateral Cephalometric Radiograph?

A

8x10

35
Q

Where is the beam directed on a Lateral Cephalometric Radiograph?

A

Towards the ear opening.

36
Q

Posteroanterior Cephalometric Radiograph aka PA Projection

A

Shows the entire skull in a posteroanterior plane (back to front).

37
Q

What is the purpose of a Posteroanterior Cephalometric Radiograph?

A

to examine facial growth and dev., disease, trauma, etc The right and left sides are not superimposed so more detail can be seen. 8x10 film Patient faces cassette.

38
Q

Where is the central beam directed in a Posteroanterior Cephalometric Radiograph?

A

perpendicular to the film toward the occipital protuberance (bone near the base of the skull).

39
Q

Waters Radiograph (sinus projection)

A

similar to posteroanterior except the center of interest is focused on the middle 1/3 of the face.

40
Q

What is the purpose of a Waters Radiograph?

A

evaluate maxillary frontal and ethmoid sinus areas. 8x10 film placed vertical with patient facing cassette and head tilted back slightly.

41
Q

Where is the central beam directed in a Waters Radiograph?

A

perpendicular through occipital protuberance with target film distance a minimum of 36 inches.

42
Q

What is the Purpose of a Reverse-Towne Radiograph?

A

used to examine fractures of the condylar neck of the mandible. 8x10 film placed vertically with patient forhead on the cassette with mouth open and head tipped down until chin touches chest.

43
Q

Where is the central beam directed in a Reverse-Towne Radiograph?

A

perpendicular through the occipital protuberance at a target-film minumum of 36 inches.

44
Q

What is the purpose of a Submentovertex Radiograph?

A

used to show the base of the skull, the position and orientation of the condyles, the sphenoid sinus and fractures of the zygomatic arch. 8x10 film. The head is extended backward until the top of the head touched the cassette. The nose is up with the midsaggital plane perpendicular to the floor. The Frankfort plane is to be vertical to the floor and parallel to the film.

45
Q

Where is the central beam directed in a Submentovertex Radiograph?

A

perpendicular to the film from below the mandible through the center of the head.

46
Q

Transcranial Radiograph (TMJ Projection)

A

A series of radiographs both open and closed mouth is essential. Has largely been replaced with a tomography of the TMJ- a moving radiograph like a panorex only with TMJ as center.

47
Q

What is the purpose of a Transcranial Radiograph?

A

aids in diagnosing ankylosis (stiffening) of the TMJ caused by fibrous or bony union via malignancies, fractures, and arthritis.

48
Q

How is film placed and where is centreal beam directed with a Transcranial Radiograph?

A

8x10 film positioned against ear and centered over the ear with the head upright

Central Beam is directed toward the center of the film with a least a 25 degree vertical angulation with point of entry 2 ½ inches higher and slightly in front of the ear. The beam comes fron the opposite side of the head and so must pass through bone, etc to see TMJ

Radiology Exam 5 (4 decks)

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