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OSI Ignacio > Chapter 4: Radiographic Imaging > Flashcards

Chapter 4: Radiographic Imaging Flashcards

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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
Tube voltage peak (kVp) is involved in the?
Contrast
26
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 __?
the greater the probability it will be converted into X-ray photons.
27
Unit of kVp?
Kilovoltage
28
Distance tube-film is involved in the ?
Quality
29
The distance tube- film affects the ?
Radiation intensity and ET If you increase the distance you inc the ET
30
A collimator is?
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.
31
Collimation reduces? And improves?
the exposed volume and patient exposure. Improve images.
32
A filter?
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
What is the inverse square law?
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
So an increase in distance will result in?
A bigger and more distorted image
35
Factors related to the object:
Thickness and density
36
Thickness of the object?
The greater the thicness of an object, the greater the radiation intensity.
37
When radiographing someone with more weight we need to inc:
3: mA, kVp, exposure time. MEK
38
Factors related to the digital receptor-film:
Films Intensifying screens Film development
39
Related to the films?
- thickness of the emulsion - screens - radiographic speed RST
40
Intensifying screens?
Creates an image receptor system that is 10 to 60 times more sensitive to xray than the film alone.
41
Film development:
Contrast, density, fog , sharpness
42
What happens when the radiation strikes the patient?
Attenuation
43
Attenuation is ?
The x-ray beam is reduced by intensity
44
2 phenomenons of attentuation?
Absorption interactions Scattering interactions
45
Absorption interactions are:
Absorption of individual photons in the beam by atoms in the absorbing tissues
46
Scattering interactions?
Photons are scattered out of the beam
47
Types of tissues exposed?
Bone and soft tissue
48
BONE vs SOFT TISSUE Which is more likely to absorb x-ray photons and which is more likely to let them pass through?
Bone Soft tissue
49
The 3 means of beam attenuation are?
Coherent scattering Photoelectric absorption Compton scattering
50
Coherent scattering is also known as?
Rayleigh Classical Elastic scattering REC
51
Coherent scattering is?
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
Coherent scattering occurs __% of the time and is responsible for the film __?
7, fog
53
Photoelectric absorption is?
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
Photoelectric absorption occurs ___% of the time?
27
55
Compton scattering is?
When the photon interacts with an outer orbital electron and the outer receives kinetic energy and recoils from the point of impact.
56
Compton scattering occurs ___% of the time?
57
57
Which of the 3 means of beam attenuation is the primary contributor to the image? And which is the secondary ?
- photoelectric - Compton
58
Which of the 3 means of beam attentuation reduces contrast?
Compton scattering
59
Geometric enlargement:
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
What are the intraoral devices in dentistry?
Backbone Periapical Bitewing Occlusal Used for: • Diagnostic information • Clinical procedures
61
Panoramic imaging (pantomography):
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
Panoramic imaging is indicated in:
Diagnostic problems requiring broad coverage of the jaws Initial evaluation Patients who do not tolerate intraoral procedures well
63
Disadvantages of panoramic imaging?
• Does not display the fine anatomic detail • Unequal magnification and geometric distorsion • Overlaped structures
64
Why are Numerous technologic innovations driving the shift from film to digital systems.
- Processing time - Film, developing (chemical solutions) - Image interpretation: enhacements, measurements, corrections. - Image transferring - Radiation (80%). ET.
65
Disadvantages of digital imaging?
- costly - expensive components - systems becoming obsolete
66
Properties of film imaging?
- emulsion - base
67
Emulsion of film imaging?
- sensitive to X-ray and visible light - silver halide grains
68
Base of film imaging?
- plastic supporting material - provides flexibility - uniformly translucent
69
Types of film imaging?
Periapical, bitewing, occlusal
70
Bitewing view:
- record the coronal portion of the maxillary and mandibular teeth - Interproximal caries, height of alveolar bone - paper tab to support the film
71
Film processing steps:
- 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
Radiation dosimetry is
the measurement, calculation and assessment of the ionizing radiation dose absorbed by an object, usually the human body.
73
3 principles of safety and protection in radiation
Justification: benefit-risk Optimisation: reduce unnecessary exposure Dose limitation: dose limits for dentists and staff
74
Safety and protection standards for patients?
- 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
Safety and protection standards for personnel:
- 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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