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Oral Surgery > Chapter 4: Radiographic imaging > Flashcards

Chapter 4: Radiographic imaging Flashcards

1
Q

What can we record in the bitewing view?

A

The coronal maxillary portion and mandibular teeth

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2
Q

What can we observe in the cephalometric radiograph?

A
  • Diseases
  • Impacted teeth
  • Trauma
  • TMJ
  • Abnormalities
  • Relationship between orofacial and dental structures
  • Growth and development
  • Treatment progression
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3
Q

Radiology is the study of

A

The study of the effects of ionising radiation on living systems

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4
Q

What happens when an atom loses an electron?

A

It becomes a positive ion, and the free electron becomes a negative ion

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5
Q

Requirement to get ionisation:

A

Energy

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6
Q

Ions formed from the atom acquire a negative or positive charge

A
  • Subatomic particle
  • Other atoms
  • Molecules
  • Ions
  • Light
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7
Q

We need a specific type of radiation to ionise the matter.
True or False.

A

True

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8
Q

What is radiation?

A

It is the emission or transmission of energy in the forms of waves or particles through space or through a material medium

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9
Q

Types of radiation

A
  • Electromagnetic radiation
  • Particle radiation
  • Acoustic radiation
  • Gravitational radiation
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10
Q

Non ionising: they do not produce enough ______

A

Energy

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11
Q

Non ionising radiations

A
  • Visible light
  • Infrared
  • Microwave radiation
  • Radio waves
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12
Q

We need enough _____ to alter the matter, to ionise

A

Energy

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13
Q

Transmission of energy through space and matter has 2 types:

A
  • Particulate
  • Electromagnetic
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14
Q

What is particulate?

A

When atoms break up releasing alpha or beta –> radioactivity

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15
Q

Is particulate dangerous?

A

Yes

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16
Q

What is electromagnetic (EM)?

A

These waves are propagating through time-space carrying electromagnetic energy

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17
Q

What is less harmful, the particulate or the electromagnetic?

A

The electromagnetic is less harmful

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18
Q

Types of EM

A
  • Gamma rays
  • X-rays
  • Ultraviolet rays
  • Visible light
  • Infrared (heat)
  • Microwaves
  • Radiowaves
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19
Q

Gamma rays and X-rays have enough energy to ionise, so they have higher energy. They are ______

A

Ionising matters

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20
Q

What radiology only involves electromagnetic radiation?

A

Oral and maxillofacial radiology

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21
Q

How does the X-ray machine work?

A

It produces an X-ray that passes through the patient’s tissues and strike a digital receptor or film to make a radiography image

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22
Q

What is an X-ray tube?

A

It is a cathode and anode situated with an evacuated glass envelop or tube

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23
Q

Who created the X-ray tube and when?

A

Wilhelm Röntgen, a German scientist on November 8, 1895
(he has a Nobel prize in physics)

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24
Q

Factors controlling the radiographic imaging

A
  • X-ray beam
  • Objects
  • Digital receptor/film
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25
Q

What happens when we modify the exposure time?

A

Changing the exposure time modifies the duration of the exposure and thus the number of protons generated

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26
Q

What does the exposure time control?

A

The density and the contrast

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27
Q

The quantity of radiation produced by an X-ray tube is ______ ______ to the tube current (mA) and the time the tube is _______ (exposure time)

A

Directly proportional, operated

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28
Q

What does the tube current control?

A

Density

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29
Q

What does mA stand for?

A

Milliamperes; a unit representing the amount of current passed through the X-ray tube

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30
Q

What does increasing the tube voltage peak (kVp) do?

A

it increases the potential difference between the cathode and the anode, increasing the energy of each electron when it strikes the target

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31
Q

The greater the energy of an electron, the _____ probability it will be converted into X-rays photons

A

Greater

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32
Q

What does the tube voltage peak involve?

A

Contrast

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33
Q

What does kVp stand for?

A

Kilo-voltage

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34
Q

What does the distance tube-film do?

A

It affects the radiation intensity and exposure time

35
Q

What does the distance tube-film involve?

A

Quality

36
Q

If you increase the distance, you _____ the exposure time

A

Increase

37
Q

What is a collimator?

A

It Is a metallic barrier with an aperture in the middle

38
Q

What is the collimation used for?

A
  • To restrict the size of the X-ray beam and the volume of the tissue irradiated
  • It reduces the exposed volume and the patient’s exposure
  • The collimator will restrict, narrow and direct the X-ray beam
39
Q

What does the collimation improve?

A

The image

40
Q

What does filtration do?

A

it removes low-energy photons from the beam while allowing high-energy photons that are able to contribute to making an image to pass through

41
Q

By law, all the units should have a _____ and a _____

A

Collimator and Filter

42
Q

What is the inverse square law?

A

The intensity of an X-ray beam is inversely proportional to the square of the distance between the source and the point of measure

43
Q

What happens when the source of the target is doubled?

A

The intensity of the beam decreases to 1/4

44
Q

The image will decrease in distance (inverted square law). True or False.

A

False. It increases in distance, the final image will be bigger

45
Q

The quality of radiography does not vary from one device to another. True or False

A

False, the quality of radiography can vary from one device to another

46
Q

X-ray beam properties

A
  1. Exposure time
  2. Tube current (mA)
  3. Tube voltage peak (kVp)
  4. Distance tube-film
  5. Collimation
  6. Filtration
  7. Inverse square law
  8. Device efficacy
47
Q

The greater the thickness of an object, the ____ the radiation intensity

A

Greater

48
Q

What does the thickness of the object increase?

A

The mA, kVp, and exposure time

49
Q

X-rays are absorbed proportionally to the mass (density) they go through. True or False

A

True

50
Q

What does the density increase?

A

The mA, kVp, and exposure

51
Q

Object properties

A
  1. Thickness
  2. Density
52
Q

Digital receptor film properties

A
  1. Films: the thickness of the emulsion, screens, radiographic speed
  2. Intensifying screens: creates an imagined receptor system that is 10 to 60 times more sensitive to x-ray than the film alone
  3. Film develop: contrast, density, fog, and sharpness
53
Q

If we have a good intensifying screen we will need so much exposure time. True or False

A

True

54
Q

When the radiation strikes the patient, ____ happens

A

Attenuation

55
Q

When attenuation happens, the X-ray beam is ____ in intensity as the body acts as a barrier

A

Reduced

56
Q

Types of attenuation

A
  • Absorption interactions (type 1): absorption of individual photons in the beam by atoms in the absorbing tissues
  • Scattering interactions (type 2): photons are scattered out of the beam
57
Q

Type of tissue exposed in interactions of X-ray with matter

A
  • Bone: hard tissue, whitish, radio-opaque
  • Soft tissues: blackish, radiolucent
58
Q

Match the letters with the numbers:
A. More likely to absorb X-ray photons
B. More likely to let them pass through

  1. Soft tissues
  2. Bone
A

A. 2
B. 1

59
Q

The 3 means of beam attenuation (absorption or scattering)

A
  • Coherent scattering
  • Photoelectric absorption
  • Compton scattering
60
Q

Coherent scattering:

A

Rayleigh, classical, elastic scattering
- Low energy photon
- Interacts with a whole atom
- It ceases to exist
- The excited generated another X-Ray photon

61
Q

Photoelectric absorption:

A
  • Primary contributor to the image
  • Incident photon interacts with an electron in an inner orbital of an atom
  • The photon ejects the electron and it becomes a recoil electron –> photoelectron
62
Q

Compton scattering:

A
  • Secondary contributor to the image (second best contributor)
  • Reduces contrast
  • The photon interacts with an outer orbital electron
  • The outer receives kinetic energy and recoils from the point of impact
63
Q

Match the letters with the numbers:
A. Happens 7% of the time
B. Happens 57% of the time
C. Happens 27% of the time

  1. Compton scattering
  2. Photoelectric absorption
  3. Cohering scattering
A

A. 3
B. 1
C. 2

64
Q

What is the best type of attenuation in terms of contribution to the image?

A

The photoelectric absorption

65
Q

In geometric enlargement:
- The image of the film is _____ than the object
- When the distance of the focal spot increases, the image ____

A
  • Larger
  • Decreases
66
Q

Intraoral devices

A
  • Backbone
  • Periodical
  • Bitewing
  • Occlusal
  • Diagnostic information
  • Clinical procedures
67
Q

What is panoramic imaging (pantomography)?

A

An X-ray source and image receptor rotate around the patient’s head and create a panoramic image of both the maxillary and mandibular dental arches and their supporting structures

68
Q

When is panoramic imaging used?

A
  • Diagnostic problems requiring broad coverage of the jaws
  • Initial evaluation
  • Patients who do not tolerate intraoral procedures well
69
Q

Problems of panoramic imaging

A
  • Does not display the fine anatomic detail
  • Unequal magnification and geometric distortion
  • Overlapped structures
70
Q

Numerous technological innovations have driven the shift from film to digital systems. True or False

A

True

71
Q

Digital imaging properties

A
  • Processing time
  • Film, developing (chemical solutions)
  • Image interpretation: enhancements, measurements, corrections
  • Image transferring
  • Radiation is reduced by 80% as the exposure time is reduced
72
Q

Disadvantages of digital imaging

A
  • Costly
  • Expensive components
  • Systems becoming obsolete
73
Q

Film imaging components

A
  1. Emulsion:
    - Sensitive to X-ray and visible light
    - Silver halide grains
  2. Base:
    - Plastic supporting material
    - Provides flexibility
    - Uniformly translucent
74
Q

Film techniques

A
  1. Periapical (several sizes)
  2. Bitewing (paper tab to support the film)
  3. Occlusal (the patient bites the film they might feel uncomfortable)
75
Q

What can we see in the periapical view?

A
  • Crowns, roots and the surrounding bone
76
Q

What can we see in the bitewing view?

A
  • Coronal portion of the maxillary and mandibular teeth
  • Interproximal caries
  • Height of the alveolar bone
77
Q

What can we see in the occlusal view?

A
  • Larger areas of the maxilla and mandible teeth
78
Q

What radiographs have intensifying screens?

A

Panoramic and Cephalometric

79
Q

Steps of film processing

A
  • Immerse exposed film in the developer
  • Rinse the developer off the film in the water bath
  • Immerse film into the fixer
  • Wash fill in water to remove the fixer
  • Dry the film and mount it for viewing
  • Darkroom and equipment
  • Automatic film processing
80
Q

What is radiation dosimetry?

A

It is the measurement calculation and assessment of the ionising radiation dose absorbed by an object, usually the human body

81
Q

Principles of safety and protection

A
  1. Justification: benefit-risk
  2. Optimisation: reduce unnecessary exposure
  3. Dose limitation: dose limits for dentist and staff
82
Q

Standards for patients

A
  • Justification; influences what the patients are selected for radiographic examination
  • Pregnancy
  • Filtration and collimation devices
  • Exposure time reduction
  • Source to skin distance: 40 cm
  • Barriers: leaded aprons and thyroid collars (for the patient)
83
Q

Standards for personnel

A
  • Avoid primary beam
  • Position and distance rule
  • Dosimetric control: dosimeters, measure absorbed dose from ionising radiation
  • Leaded aprons

Oral Surgery (5 decks)

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