Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Radiology Exam 5 > Chapter 22 > Flashcards

Chapter 22 Flashcards

1
Q

What does panoramic radiography refer to?

A

Technique for producing a broad view image of the entire dentition both maxillary and mandibular on a single film. An enlongated screen film 5 or 6 x 12 is placed in a cassette and positioned extra orally.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What can a panoramic depict

A

Not only the teeth and alveolar bone but also the sinuses, the TMJ, the maxilla and the mandible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Panorex is best used for

A
  • Large caries
  • Examining large areas of the face/jaws
  • Locating impacted teeth or root tips
  • Evaluating trauma, lesions, diseases
  • Assessing growth and development
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Advantages of a panorex

A
  • Depicts greater areas of diagnostic quality with less radiation than a full mouth series
  • Easier for the patient to see and understand
  • Less discomfort for the patient
  • Since easier, less retakes
  • Better time management for the dental team
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Tomography

A

Specialized radiographic technique used to show images of structures located within a selected plane of tissue while blurring structure outside of the selected plane

It utilizes a narrow beam of x-rays to image a curved layer or slice of tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

During tomography and rotational panoramic radiography

A

The tube head and film do not remain stationary as intraoral radiography but moves in relationship to each other to focus the x-ray beam on a selected layer of interest while blurring out structures outside of that layer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Where is the patients head during a panoramic

A

Between the tube head and the film cassette

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How long will the tubehead rotate around a patients head during panoramic

A

15-20 seconds recording a selected image within the focal layer blurring out the spine, skull, etc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

These are always opposite of each other to create a perpendicular angle for the x-ray beam to film

A

Tube head and cassette

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Rotational centers

A

The axis on which the tube head and the cassette roatate is the functional focus of the projection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

The x-ray beam in a panoramic

A

Emitted from a narrow vertical slit in the tube head and is constricted to form a narrow band of radiation in the shape of a trough, this lessens the area exposed to radiation to the area wanted depicted

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

If the cassette is round

A

It rotates in concert with the rotations around the patient to keep exposing a new area of film

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

In a hard flat cassette

A

it will move to the side in concert with the other rotations to keep exposing new film

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Double center rotation

A

The tube head and cassette rotate to the mid-line then the radiation stops until the patient is shifted then the radiation resumes along with continuation of the rotation. A split image results

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Triple center rotation

A

Three centers of rotation are used but the sight of the x-ray beam is so efficient that a continuous image results on the film

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Moving center rotation

A

Most modern machines fall in this category. The elliptical pattern closely matches the arc of the teeth. A continuous image is produced. The horizontal and vertical magnification are relatively constant. The elliptical pattern can be adjusted to fit most people

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Projections in the horizontal and the vertical planes

A

do NOT have the same focus of projection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Horizontal plane

A

Focus is at the center of the rotation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Vertical plane

A

Focus is at the target in the tube head

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Difference of the vertical and horizontal

A

Accounts for the degree of image distortion that is characteristic of a panorex

21
Q

Width of the trough and the distance from the rotational center is controlled by

A

the speed of the moving cassette controlled by manufacturer

22
Q

Width of the trough increases

A

when the distance is increased

23
Q

Types of panorex machines

A

Stand up
Sit down
Flexible cassettes
Hard cassettes

24
Q

What are 4 components that the different type of panoramic machines have in common

A
  1. Rotational x-ray
  2. Cassette holder on drum
  3. Head positioner guides
  4. Exposure control panel
25
Q

X-ray tube head

A

The fixed vertical position is usually around 8 degrees or pointing slightly upward. The PID is collimated with a lead diaphragm in the shape of a narrow slit opening,

26
Q

Where does the x-ray beam strike

A

From the back of the head

27
Q

Cassette holder

A

Can be flat or a drum and rotates in front of the patient and rotates or moves to the side to advance the film into the x-ray beam as the tube head rotates

28
Q

Intensifying screens

A
  • Transfers x-ray energy into visible light
  • Allows for much less radiation since intensified
  • Smooth plastic almost looks like cardboard
  • Coated with minute fluorescent crystals called phosphors
  • When exposed to x-rays phosphors flouresce and emit blue or green light
29
Q

Screen film must be placed

A

Between intensifying screen inside of a cassette either rigid or flexible

30
Q

Blue sensitive film

A

Must be paired with blue light screens. This is a conventional tungstate screen where the phosphors emit blue light

31
Q

Newer rare earth screen phosphors

A

emit green light and must also be paired with green sensitive film. The rare earth need even less radiation then blue

32
Q

Head positioner guides

A

Most machines are equipped with a bite block or forehead rest. Side positioners or a mirror is used for determining the correct alignment of the mid-saggital plane and a chin rest to correctly locate how far up or down the arches should be positioned. Some unites have beams of light that shine on the patients face to guide the operator to correct placement of the head

33
Q

Exposure control panel

A

Allows for the selection of the mA and kVp as recommended by the manufacturer according to size of the patient and the density of the tissues to be imaged

34
Q

Why would kVp controls be adjusted up

A

For better penetration of larger patients or denser tissues

35
Q

Why would kVp control be adjusted down

A

For children and edentulous patients

36
Q

Exposure time

A

Pre-set and is usually 15-20 seconds. All machines have a dead man’s switch which means you have to hold the button down for the entire 15-20 seconds

37
Q

Lead aprons and panoramics

A

Are used with panoramic radiographs but not with a thyroid collar. The beam will be obstructed and the film not diagnostic

38
Q

Correct head positioning

A

MUST have correct head position to place desired structures within the focal trough. Since the trough is pre-determined, it is the operators responsibility to properly place the patient

39
Q

What are the 3 facial landmarks that are important to position the patient

A

Mid-saggital plane
Ala-tragus line
The frankfort plane

40
Q

Mid saggital plane

A

Imaginary line divides the patient into a right and left halves down the center of the nose assuming the parient is positioned perpendicular to the floor

41
Q

Ala Tragus Line

A

Imaginary line from the ala of the nose (side of the nose) through the tragus (front of the ear)

42
Q

The Frankfort plane

A

Imaginary line from the orbital ridge (under the eye) to the acoustic meatus (ear opening), When positioned correctly, the line will be parallel to the floor

43
Q

Patient too far forward in the trough

A

Anterior teeth will be blurred and diminished in width

44
Q

Patient to far back in trough

A

Anterior teeth are blurred and magnified

45
Q

Patient head tilted or rotated

A
  • Teeth closer to the film will appear smaller

- Teeth closer to the rotational center (farther from film) will appear magnified

46
Q

Patients chin tipped to low (frankfort plane angled downward)

A

The image will appear as an exaggerated smile, condyles tilt upward

47
Q

Patients chin is tipped up

A
  • The image will appear as an exaggerated frown

- Usually lose condyles in the image

48
Q

Patient is slumped

A

Radiation is trying to pass through compressed vertebrae and so widespread RO is superimposed over the anterior teeth

49
Q

Patient prep errors

A
  1. Failure to remove any object made of metal
  2. Thyroid collar is NOT used
  3. Thickly padded clothing may impede tube head
  4. Patients must understand and cooperate by holding still and resting tongue against the palate and close lips around bite guard

Radiology Exam 5 (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions