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OSI Ignacio > Chapter 4: Radiographic Imaging > Flashcards

Chapter 4: Radiographic Imaging Flashcards

1
Q

Radiobiology is ?

A

The study of the effects of ionising radiation on living systems

The health effects of radiation

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2
Q

When an atom looses an electron?

A

It becomes a positive ion

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3
Q

When an atom gains an electron?

A

It becomes a negative ion

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4
Q

What is required for ionisation to occur?

A

Energy

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5
Q

How do atoms become ions?

A

By acquiring a negative or positive charge by gaining or losing electrons

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6
Q

We need a specific type of __ to ionise the matter?

A

Radiation

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7
Q

Radiation is?

A

Emission or transmission of energy in the form of waves or particles through space or through a material medium

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8
Q

Radiation includes:

A

(4)
- electromagnetic
- particle
- acoustic
- gravitational

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9
Q

Non ionising radiation are:

A

Visible light
Infrared
Microwave
Radio waves

  • they don’t have sufficient energy
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10
Q

2 forms/types of radiation are?

A
  • particulate
  • electromagnetic

They have enough energy to alter the matter

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11
Q

Particulate?

A

Atoms break up releasing alpha or beta particles—> radio-activity

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12
Q

Electromagnetic?

A

Waves propagating through space-time carrying electromagnetic radiant energy

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13
Q

What are electromagnetic radiations?

A

(7)
Gamma rays
X-rays
Ultraviolet rays
Visible light
Infrared (heat)
Microwaves
Radio waves

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14
Q

Which of the electromagnetic radiations have the highest energy and are able to ionise matter

A

Gamma rays and x-rays

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15
Q

Oral and maxillofacial radiology involves only?

A

ER

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16
Q

X-ray machine produces?

A

X-ray that pass through a patient’s tissues and strike a digital receptor or film to make a radiographic image

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17
Q

X-ray tube?

A

A cathode and anode situated within an evacuated
glass envelope or tube

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18
Q

Who created the X-ray tube? When and how?

A
  • Wilhelm Röntgen. German physics prof.
  • On Novembre 8, 1895
  • Experimenting with Crookes tubes
  • “X” unknown radiation
  • Röntgen radiation
  • Nobel Prize in Physics
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19
Q

Factors controlling the radiographic imaging?

A

X-ray beam
Object
Digital receptor/film

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20
Q

Factors regarding the x-ray beam:

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
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21
Q

Exposure time?

A

Changing the exposure time
modifies the duration of the
exposure and thus the number
of photons generated.

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22
Q

Exposure time controls ?

A

density and contrast.

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23
Q

Tube current (mA) controls?

A

Density
MAD

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24
Q

The unit of tube current is?

A

mA
Milliamperes

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25
Q

Tube voltage peak (kVp) is involved in the?

A

Contrast

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26
Q

Increasing the kVp increases the potential difference between the cathode and the anode, increasing the energy of each electron when
it strikes the target. The greater the
energy of an electron __?

A

the greater the probability it will be converted into X-ray photons.

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27
Q

Unit of kVp?

A

Kilovoltage

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28
Q

Distance tube-film is involved in the ?

A

Quality

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29
Q

The distance tube- film affects the ?

A

Radiation intensity and ET

If you increase the distance you inc the ET

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30
Q

A collimator is?

A

a metallic barrier with an aperture in the middle used to restrict the size of the X-ray beam and the volume of tissue irradiated.

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31
Q

Collimation reduces? And improves?

A

the exposed volume and patient
exposure.

Improve images.

32
Q

A filter?

A

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

33
Q

What is the inverse square law?

A

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

When the distance from the
source to a target is doubled,
the intensity of the beam
decreases to one quarter

34
Q

So an increase in distance will result in?

A

A bigger and more distorted image

35
Q

Factors related to the object:

A

Thickness and density

36
Q

Thickness of the object?

A

The greater the thicness
of an object, the greater the radiation intensity.

37
Q

When radiographing someone with more weight we need to inc:

A

3:
mA, kVp, exposure time.

MEK

38
Q

Factors related to the digital receptor-film:

A

Films
Intensifying screens
Film development

39
Q

Related to the films?

A
  • thickness of the emulsion
  • screens
  • radiographic speed

RST

40
Q

Intensifying screens?

A

Creates an image receptor system that is
10 to 60 times more sensitive to xray than
the film alone.

41
Q

Film development:

A

Contrast, density, fog , sharpness

42
Q

What happens when the radiation strikes the patient?

A

Attenuation

43
Q

Attenuation is ?

A

The x-ray beam is reduced by intensity

44
Q

2 phenomenons of attentuation?

A

Absorption interactions
Scattering interactions

45
Q

Absorption interactions are:

A

Absorption of individual photons in the beam by atoms in the absorbing tissues

46
Q

Scattering interactions?

A

Photons are scattered out of the beam

47
Q

Types of tissues exposed?

A

Bone and soft tissue

48
Q

BONE vs SOFT TISSUE
Which is more likely to absorb x-ray photons and which is more likely to let them pass through?

A

Bone
Soft tissue

49
Q

The 3 means of beam attenuation are?

A

Coherent scattering
Photoelectric absorption
Compton scattering

50
Q

Coherent scattering is also known as?

A

Rayleigh
Classical
Elastic scattering

REC

51
Q

Coherent scattering is?

A

When a low energy photon interacts with a whole atom , it ceases to exist and the excited generates another x-ray photon that’s emitted in different direction

52
Q

Coherent scattering occurs __% of the time and is responsible for the film __?

53
Q

Photoelectric absorption is?

A

When an incident photon interacts with an electron in an inner orbital of an atom and the photon ejects the electron and it becomes a recoil electron (photo electron)

54
Q

Photoelectric absorption occurs ___% of the time?

55
Q

Compton scattering is?

A

When the photon interacts with an outer orbital electron and the outer receives kinetic energy and recoils from the point of impact.

56
Q

Compton scattering occurs ___% of the time?

57
Q

Which of the 3 means of beam attenuation is the primary contributor to the image? And which is the secondary ?

A
  • photoelectric
  • Compton
58
Q

Which of the 3 means of beam attentuation reduces contrast?

A

Compton scattering

59
Q

Geometric enlargement:

A
  1. The image on the film is larger than the
    object.
  2. When the distance of the focal spot
    increases, the image decreases
  3. Minimize the distance between the object
    and the mana rapantar redure tha
60
Q

What are the intraoral devices in dentistry?

A

Backbone
Periapical
Bitewing
Occlusal

Used for:
• Diagnostic information
• Clinical procedures

61
Q

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

62
Q

Panoramic imaging is indicated in:

A

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

63
Q

Disadvantages of panoramic imaging?

A

• Does not display the fine anatomic detail
• Unequal magnification and geometric distorsion
• Overlaped structures

64
Q

Why are Numerous technologic innovations driving the shift from film to digital systems.

A
  • Processing time
  • Film, developing (chemical solutions)
  • Image interpretation: enhacements, measurements, corrections.
  • Image transferring
  • Radiation (80%). ET.
65
Q

Disadvantages of digital imaging?

A
  • costly
  • expensive components
  • systems becoming obsolete
66
Q

Properties of film imaging?

A
  • emulsion
  • base
67
Q

Emulsion of film imaging?

A
  • sensitive to X-ray and visible light
  • silver halide grains
68
Q

Base of film imaging?

A
  • plastic supporting material
  • provides flexibility
  • uniformly translucent
69
Q

Types of film imaging?

A

Periapical, bitewing, occlusal

70
Q

Bitewing view:

A
  • record the coronal portion of the maxillary and mandibular teeth
  • Interproximal caries, height of alveolar bone
  • paper tab to support the film
71
Q

Film processing steps:

A
  • Immerse exposed film in developer
  • Rinse developer off film in water bath
  • Immerse film in fixer
  • Wash film in water bath to remove fixer
  • Dry film and mount for viewing
72
Q

Radiation dosimetry is

A

the measurement, calculation and assessment of the ionizing radiation dose absorbed by an object, usually the human body.

73
Q

3 principles of safety and protection in radiation

A

Justification: benefit-risk
Optimisation: reduce unnecessary exposure
Dose limitation: dose limits for dentists and staff

74
Q

Safety and protection standards for patients?

A
  • Justification: influences what patients are
    selected for radiographic examination
  • Pregnancy
  • Filtration a collimation devices
  • Exposure time reduction
  • Source to skin distance: 40 cm
  • Barriers: leaded aprons and thyroid collars
75
Q

Safety and protection standards for personnel:

A
  • Avoid primary beam
  • Position and distance rule
  • Dosimetric control: Dosimeters. Measure
    absorded dose from ionizina radiation
  • Leaded aprons

OSI Ignacio (10 decks)

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