Chapter 25: Panoramic Imaging Flashcards

Principles, Equipment and Guidelines of Panoramic Imaging

1
Q

List the three main components of the panoramic machine.

A
  • x-ray tubehead
  • head positioner
  • exposure controls
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2
Q

Define the term: edentulous patient

A

a patient without teeth

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3
Q

Define the term: radiolucency

A

an area on a dental image appears radiolucent ((dark/black) due to readily allowing the passage of the x-ray beam so that more x-rays reach the image receptor

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4
Q

If the patient’s teeth are incorrectly positioned anterior to the focal trough, how does the image appear?

A

the anterior teeth appear narrow and distorted and a pronounced overlap of the premolars occur

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5
Q

Define the term: maxillary sinuses

A

paired cavities or compartments of bone located within the maxilla and located superior to the maxillary posterior teeth (appear radiolucent)

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6
Q

How should the patient position their lips during a panoramic exposure?

A

closed around the bite block

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7
Q

How do the structures located within the focal trough appear?

A

well-defined

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8
Q

Which part(s) of the head positioner stabilizes the patient’s anterior-posterior plane?

A

the chin rest and bite block

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9
Q

Does the panoramic tubehead rotate behind or in front of the patient’s head?

A

behind

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10
Q

Define the term: extraoral receptor

A

an image receptor is placed outside the mouth to examine large areas of the skull or jaws

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11
Q

Define the term: sinus

A

a hollow space, cavity, or recess in bone (appears radiolucent)

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12
Q

How do you prevent a ghost image from occurring on a panoramic image?

A

instruct the patient to remove all radiodense objects in the head or neck region prior to exposure

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13
Q

Define the term: Frankfort plane

A

the imaginary plane that intersects the orbital rim of the eye and opening of the ear

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14
Q

Why is a panoramic image contraindicated when diagnosing caries, periodontal disease, or periapical lesions?

A

the images are not as defined or sharp as intraoral images

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15
Q

Define the term: dentition

A

the character of a set of teeth, including their number, kind, and location/arrangement

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16
Q

How should the patient position their tongue during a panoramic exposure?

A

against the palate

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17
Q

Define the term: posterior

A

towards the back

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18
Q

Define the term: panoramic receptor

A

an image receptor used in panoramic examinations that show a wide view of the maxilla and mandible

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19
Q

Should a thyroid collar be used when exposing a panoramic image?

A

No

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20
Q

Define the term: mandible

A

the lower jaw

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21
Q

Define the term: focal trough / image layer

A

a three-dimensional curved zone in which structures are clearly demonstrated on a panoramic image

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22
Q

Define the term: contrast

A
  • how sharply dark and light areas are differentiated or separated on an image
  • the difference in the degrees of blackness (densities) between adjacent areas on a dental image
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23
Q

Define the term: density

A

the overall darkness or blackness of an image

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24
Q

Define the term: maxilla

A

the upper jaw

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25
Q

Define the term: edentulous

A
  • without teeth
  • an area where teeth are no longer present
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26
Q

Define the term: midsagittal plane

A

an imaginary line or plane passing through the center of the body that divides it into right and left halves

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27
Q

Define the term: radiolucent

A

the portion of an image that is dark or black, due to the structure readily permitting the passage of the x-ray beam and allowing more x-rays to reach the image receptor

28
Q

Define the term: non-diagnostic image

A

an image that is not diagnostically accurate due to technique errors and must be retaken

29
Q

List the advantages of panoramic imaging.

A
  • more anatomic structures are viewed on a panoramic image versus intraoral images
  • the panoramic exposure is simple to learn
  • easy patient cooperation
  • minimal exposure to x-radiation
30
Q

Define the term: radiopaque

A

the portion of an image that is light or white, due to the structure resisting the passage of the x-ray beam and limiting the amount of x-rays that reach the receptor

31
Q

Define the term: panoramic image

A

an image that shows the wide view of the maxilla and the mandible surrounding structures

32
Q

Define the term: extraoral image

A
  • an image that results when an image receptor is placed outside the mouth and is exposed to x-rays
  • used to examine large areas of the skull or jaws
33
Q

Define the term: ghost image

A

an artifact on a dental image produced when a radiodense object (ex: earring) is penetrated twice by the x-ray beam (appears radiopaque)

34
Q

Define the term: head positioner

A
  • one of the component parts of a panoramic unit that is used to position and stabilize the patient’s head
  • includes a chin rest, notched bite-block, forehead rest, and lateral head supports
35
Q

What is the typical exposure time of a panoramic image?

A

10-30 seconds

36
Q

Define the term: double image

A

results when an anatomic structure that is located behind the moving rotation center is penetrated twice by the x-ray beam

37
Q

How does a panoramic collimator differ from an intraoral collimator?

A

the panoramic is a lead plate with an opening in the shape of a narrow slit, while an intraoral collimator is a lead plate with a small round or rectangular opening

38
Q

List some disadvantages of panoramic imaging.

A
  • the image quality is not as sharp as intraoral images
  • objects outside the focal trough cannot be viewed
  • dimensional distortion can easily occur
  • high equipment cost
39
Q

Define the term: body of the mandible

A

the U-shaped horizontal portion of the mandible that extends from ramus to ramus

40
Q

Define the term: spine

A

a sharp, thornlike projection of bone (appears radiopaque)

41
Q

Define the term: radiopacity / radiodensity

A

an area on a dental image appearing radiopaque (light/white) due to resisting the passage of the x-ray beam and limiting the amount of x-rays that reach the image receptor

42
Q

Define the term: exposure

A

a measure of ionization produced in air by x-radiation or gamma radiation

43
Q

If the patient’s teeth are incorrectly positioned posterior to the focal trough, how does the image appear?

A

the teeth appear widened and distorted and the roots of the anterior teeth may be cut off

44
Q

True or false: The vertical angulation of the panoramic tubehead does not vary.

A

True

45
Q

Define the term: hyoid bone

A

a horseshoe-shaped bone that lies below the mandible, between the chin and thyroid cartilage (appears radiopaque on a panoramic image)

46
Q

Define the term: nasal cavity / nasal fossa

A

a pear-shaped compartment of bone located superior to the maxilla (appears radiolucent)

47
Q

Define the term: distortion

A
  • a geometric characteristic that refers to a variation in the true size and shape of the object being imaged
  • influenced by object-receptor alignment and the vertical angulation of the x-ray beam
48
Q

Define the term: ramus

A

vertical portion of the mandible that is found posterior to the third molar

49
Q

Define the term: rotation center

A

in panoramic imaging, the axis or pivotal point on which the image receptor and the x-ray tubehead rotate around the patient

50
Q

Define the term: extraoral imaging

A

an inspection of large areas of the skull or jaws that requires the use of extraoral imaging receptors

51
Q

How do the structures located outside the focal trough appear?

A

blurred or indistinct

52
Q

How does the panoramic image appear if the patient’s head is incorrectly turned during exposure?

A

the side of the head farthest from the receptor appears magnified and the side of the head closest to the receptor appear smaller

53
Q

Define the term: exposure factors

A

factors that influence the density of an image (ex: milliamperage, kilovoltage, exposure time)

54
Q

Define the term: anterior

A

towards the front

55
Q

What is the cause of a ghost image error on a panoramic image?

A

any radiodense materials were not removed prior to exposure

56
Q

Define the term: mandibular condyle

A

a rounded projection of bone extending from the posterosuperior border of the ramus of the mandible

57
Q

List the six anatomic requirements of a diagnostic panoramic image.

A
  • dentition
  • ramus and cervical spine
  • nasal cavity and maxillary sinus
  • body of the mandible
  • mandibular condyle
  • hyoid bone
58
Q

Does the panoramic receptor rotate behind or in front of the patient’s head?

A

in front of

59
Q

Define the term: extraoral

A

outside the mouth

60
Q

Define the term: dentulous

A
  • with teeth
  • areas that exhibit teeth
61
Q

Define the term: panoramic

A

a wide view

62
Q

Define the term: real image

A

in panoramic imaging, the image that is recorded when a structure is located between the receptor and the moving rotation center

63
Q

Which part(s) of the head positioner stabilize the patient’s vertical and horizontal planes?

A

the lateral head supports

64
Q

Define the term: edentulous zone

A

an area where teeth are no longer present

65
Q

Define the term: sharpness

A
  • refers to the capability of the image receptor to reproduce the distinct outlines of an object
  • influenced by focal spot size and movement
66
Q

Define the term: panoramic imaging

A

an extraoral technique used to examine the upper and lower jaws on a single image