Brainscape's Knowledge GenomeTM

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


See full index

Dentistry Module 4 > Radiology > Flashcards

Radiology Flashcards

1
Q

What important legislation is in place regarding Ionising radiation?

A
  • ionising radiation regulations 2017
  • ionising radiation (medical exposure) regulations 2017
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a radiograph?

A

An image produced by x-rays passing through an object and interacting with photographic emulsion on a film.

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

What is used to capture a digital x-ray image?

A

A solid state sensor or Photo-stimulable phosphor plate

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

In dentistry, what tissues are of interest in regards to radiographs?

A

Mineralised and demineralised tissue

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

What would demineralised tissue on a dental radiograph indicate?

A

Caries and other dentally related disease

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

What type of radiograph matches the description:

  1. Film/ sensor is placed inside the mouth next to the area of interest
  2. Radiation source is directed at the areas from an external position
A

Intra-oral radiograph

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

What are the three main types of intra-oral radiograph?

A
  • periapical
  • bitewing
  • occlusal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What type of radiograph matches the description:

  1. Nothing placed inside the mouth
  2. Radiation source and image receptor are both positioned outwith the mouth
A

Extra-oral radiograph

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

What can DPT also be referred to as?

A

OPT and OPG

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

What is contained within the nucleus of an atom?

A

Protons and neutrons

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

Are protons +ve, -ve or no charge?

A

+ve charge

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

Are neutrons +ve, -ve or no charge?

A

No charge

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

Are electrons +ve, -ve or no charge?

A

-ve charge

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

How many electrons are in the K shell (closest to nucleus)?

A

2

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

How many electrons are in the L shell of an atom?

A

8

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

What can move from shell to shell but cannot exist between shells?

A

Electrons

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

Which electrons in an atom will have the greatest binding energy?

A

Outer electrons

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

What is an atom with the same number of protons but a different number of neutrons referred to as?

A

An isotope

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

Describe a radio-isotope

A

An isotope with unstable nuclei which undergoes radioactive disintegration

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

What is a negatively charged ion called?

A

An anion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is a positively charged ion called?

A

A cation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What type of particles have these features?:

Made up of 2 protons and 2 neutrons
- large size
- +ve charge
- slow speed
- penetrate only 1-2mm in tissue
- 4-8 MeV energy
- extensive ionisation

A

Alpha particles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What type of particles have these features?:

  • Electrons
  • small size
  • -ve charge
  • fast speed
  • penetrate 1-2cm in tissue
  • 100keV-6MeV energy
  • ionisation
A

Beta particles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What type of rays is part of the electromagnetic radiation spectrum, has no size or charge and has very fast speed , passing through tissues?

A

Gamma rays

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What type of rays are x-rays in dentistry almost identical to? And what is the slight difference?

A

Gamma rays, except x-rays have lower energy values

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

When is ionisation a problem?

A

When it occurs in living cells, can cause damage to DNA leading to tumours and cancer.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What size of wavelength do gamma rays have?

A

Small wavelength

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Define the electromagnetic spectrum

A

A stream of photons that have no mass

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is measured in electron volts (eV)?

A

Energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is measured in cycles per second or hertz?

A

Frequency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is measured in metres or nanometres?

A

Wavelength

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

One cycle of a wave length is what shape?

A

S-shaped

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is the number of wavelengths that travel every second the same as?

A

Frequency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is the wavelength spectrum for visible light?

A

400-700nm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What is the domestic electricity supply?

A

220/240 volts
50 hertz

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What is the SI unit of potential difference? And what does it measure?

A

Volts
It measures voltage or electromotive force

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Describe an electrical circuit using a dc supply

A

A current passes along a wire by the movement of electrons and through an electrolyte by the movement of ions, from the positive terminal to the negative terminal.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

In the example of an old-fashioned electric fire, how is heat given off?

A

By means of convection and radiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

How do electrons produce heat?

A

By vibrating

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What are the three basic components involved in taking a radiograph?

A
  1. X-ray source
  2. Object
  3. Receptor
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What is key to the quality of an image?

A

The relationship of X-ray source, object and receptor to one another

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What are three types of intra-oral radiograph?

A
  • periapical
  • bitewing ( horizontal and vertical)
  • occlusal (maxilla and mandible)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

When taking an intra-oral radiograph, where would the receptor be placed?

A

Inside the mouth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

When taking an extra-oral radiograph, where would the receptor be placed?

A

Alongside the patient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What are five types of extra-oral radiographs?

A
  • dental panoramic tomogram
  • lateral cephalogram
  • PA or AP mandible
  • lateral oblique mandible
  • Occipital-mental views of facial bones
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

On a peri-apical radiograph, what should be visible?

A

The crown to the apices of the root, and inter-proximal spaces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What are the limitations of a horizontal bitewing?

A

You are not able to visualise the roots

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What radiograph would you consider taking if you wanted to assess bone levels of posterior teeth?

A

Bitewing, either horizontal or vertical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

What type of extra-oral radiograph is described:

The x-ray tube rotates round the patients head with a constant long exposure of 14 seconds, forming an image of the patient’s teeth and supporting structures

A

DPT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

What type of extra-oral radiograph is described:

A standardised and reproducible form of skull radiography, used extensively in orthodontics to asses the relationships of the teeth to the jaws and the mandible to the rest of facial skeleton

A

Lateral cephalogram

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

What type of extra-oral radiograph is described:

Shows fractures of the mandible and is used in conjunction with a DPT. it requires two views taken at right angles to one another to show full extent of fracture.

A

Posterior-anterior mandible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

It is common for there to be multiple fractures in the mandible. True or false?

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

What type of extra-oral radiograph is described:

Most commonly carried out in a dental hospital in children that cannot tolerate bitewings. Also carried out on adults for, mandibular fractures if a DPT is not available.

A

Lateral oblique mandible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

What type of extra-oral radiograph is described:

Most commonly carried out in the first instance when patient reports with facial trauma. Shows fractures of the orbit, maxilla and zygomatic arches. Two views are taken, the first angle at 10 degrees and the second angle at 30 degrees.

A

Occipito-mental views of facial bone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

When taking an occipital mental view of the facial bones, why is it beneficial to take the films erect?

A

As this can help demonstrates fluid levels in antra (sinus)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

Why are intra-oral radiographs in more detail that extra-oral?

A

Because the object is closer to the receptor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

What selection criteria helps decide the most appropriate form of imaging required when deciding what radiograph to take?

A

FGDP selection criteria for dental radiography

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

What are the two main types of technique used for intra-oral radiographs?

A
  • paralleling technique
  • bisected angle technique
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

What is the standardised intra-oral technique?

A

Paralleling technique

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

When would you opt for the bisected angle technique over the paralleling technique?

A

When a patient cannot tolerate a holder in their mouth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

What is the main issue surrounding bisected angle technique?

A

Exposure of patients fingers to radiation as they are required to hold film in mouth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

What is the downside of the paralleling technique?

A

Holders are bulky and may not be tolerated by patient.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

What part of the mouth are blue holders used to visualise?

A

Anterior teeth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

What part of the mouth are yellow holders used to visualise?

A

Posterior teeth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

What colour of holder is used for bitewings?

A

Red holder

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

What colour of holder is used for endodontic procedures?

A

Green holder

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

What are the three components of holders?

A
  1. Bite-block
  2. Indicator arm/rod
  3. Aiming ring
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

What is the function of a bite-block?

A

Retains the receptor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

What is the function of the indicator arm/rod?

A

Fits into the bite-block

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

What is the function of the aiming ring?

A

Slides onto the arm to establish alignment of collimator with receptor, guiding direction of the x-ray beam

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

What is a receptor?

A

The object an image is taken on

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

what type of receptors are used in dundee dental hospital?

A

Phosphor plates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

What reduces the variables in geometry?

A

Use of a holder

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

What are examples of variables in geometry?

A
  • Receptor-tooth relationship
  • X-ray tube position
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

How should the vertical plane of the film be positioned?

A

So that it is parallel to the long axis of the tooth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

How should the horizontal plane of the film be positioned?

A

Parallel to the central arch under examination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
77
Q

If the film isn’t parallel with the tooth vertically, what may happen?

A

Distortion of the image (teeth elongated and apices missing)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
78
Q

If horizontal positioning of the film is incorrect what may happen?

A

Teeth appear overlapped, obscuring pathology

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
79
Q

What angle should the x-ray beam be to the tooth/receptor?

A

90 degrees ( right angle )

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
80
Q

If the angle of the x-ray beam is up too much, how will the image be distorted?

A

Elongation of image

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
81
Q

If the angle of the x-ray beam is down too much, how will the image be distorted?

A

Fore-shortening of image

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
82
Q

What is the rectangular attachment at the end of the x-ray tube known as?

A

Collimater

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
83
Q

what will help achieve the most diagnostic, reproducible image?

A

Having the 4 corners of the collimator fitting nicely into the aiming ring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
84
Q

What two factors affect image size?

A
  1. X-ray source to receptor distance
  2. Object to receptor distance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
85
Q

Explain how the object comes to appear larger on the receptor

A

X-ray beam spreads out in all directions from the source and it continues to spread as it passes through the object, thus making it appear larger.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
86
Q

What action should be taken in regards to the x-ray source in order to get a more accurate depiction of the image?

A

X-ray source should be positioned further away from the object (beam diverges less)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
87
Q

What should the distance between source and film be?

A

Long

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
88
Q

What should distance between tooth and film be?

A

Short

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
89
Q

What is ‘cone cutting’ a result of?

A

Vertical angulation, when corners of the collimator have not been touching the guiding ring.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
90
Q

What are the four main barriers to good positioning?

A

-mouth size
-gag reflex
-film size
-digital sensor size and shape

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
91
Q

What are the 4 most common sizes of film/ PSP receptors?

A

0, 1, 2, 4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
92
Q

What should the film size be for:

Periapical radiograph of anterior adult teeth

A

0 or 1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
93
Q

What should the film size be for:

Periapical radiograph of anterior adult teeth using bisected angle technique

A

2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
94
Q

What should the film size be for:

Periapical radiograph of posterior adult teeth

A

2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
95
Q

What should the film size be for:

Bitewing radiograph of adult teeth

A

2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
96
Q

What should the film size be for:

Periapical radiograph of anterior children’s teeth

A

0

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
97
Q

What should the film size be for:

Periapical radiograph of posterior children’s teeth (deciduous and permanent)

A

Deciduous = 0
Permanent = 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
98
Q

What should the film size be for:

Bitewing radiograph of children over 10

A

2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
99
Q

What should the film size be for:

Bitewing radiograph of children under 10

A

0 or 1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
100
Q

what is the “controlled area”?

A

The area in the immediate vicinity around the x-ray source

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
101
Q

What material is the cathode made from? And why?

A

Tungsten, because it has a very high melting point so can withstand the production of heat from x-rays

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
102
Q

What materials make up the anode?

A

Tungsten and copper

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
103
Q

What are the two types of x-ray spectra?

A
  1. Continuous spectrum
  2. Characteristic spectrum
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
104
Q

What x-ray spectra is bremsstrahlung radiation associated with?

A

Continuous spectrum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
105
Q

What is the negatively charged electron from the cathode attracted to?

A

The positively charged atom of tungsten within the anode

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
106
Q

What type of deflections are most common and associated with low energy photons?

A

Small deflections

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
107
Q

What type of deflections are less Likely and associated with high energy photons?

A

Large deflections

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
108
Q

What is maximum photon energy directly related to?

A

KV across the x-ray tube

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
109
Q

What is termed the “ejected orbital electron”?

A

An incident electron that knocks a k shell electron out

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
110
Q

What is line spectra relating to K and L shells associated with?

A

Characteristic spectrum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
111
Q

Spectra relating to which atomic shell is of diagnostic importance?

A

K shell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
112
Q

What kV value must x-rays be operating above in order for the characteristic spectrum to be produced?

A

Above 69.5kV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
113
Q

If x-ray tube operates below 69.5kV, what radiation will be produced?

A

Bremsstrahlung radiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
114
Q

What two divisions make up the electromagnetic spectrum?

A

Non-ionising and ionising radiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
115
Q

If the wavelength is large, what division of EM spectrum radiation is most likely associated?

A

Non-ionising radiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
116
Q

If the wavelength is small, what division of EM spectrum radiation is most likely associated?

A

Ionising radiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
117
Q

Random change in direction after hitting something

A

Scattering

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
118
Q

Deposition of energy in tissues

A

Absorption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
119
Q

The number of x-ray photons in a defined area of the beam

A

Intensity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
120
Q

What happens to the energy of x-ray photons the further from the source of radiation you go?

A

Energy decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
121
Q

Reduction in intensity of beam, due to scattering and absorption

A

Attenuation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
122
Q

Removal of electron from neutral atom to give -ve (electron) & +ve (atom) ions

A

Ionisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
123
Q

The ability of photons to pass through or into tissues/materials

A

Penetration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
124
Q

What are the four types of x-ray interactions that can occur when x-ray photons hit an object?

A
  1. Completely scattered with no loss of energy
  2. Absorbed with total loss of energy
  3. Scattered with some absorption & loss of energy
  4. Transmitted unchanged
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
125
Q

What is internal scatter?

A

When some of the radiation passes down into patients body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
126
Q

How would you describe scatter of x-ray photons?

A

Unpredictable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
127
Q

Define radiation dose

A

The amount of radiation absorbed by the patient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
128
Q

Where are low energy photons often absorbed?

A

Soft tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
129
Q

What type of photon energy is most likely to cause biological damage?

A

Low energy photons absorbed by soft tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
130
Q

What do properties of radiation depend on?

A

Wavelength

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
131
Q

The item the x-ray image is formed on

A

Image receptor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
132
Q

Give three examples of image receptors

A

Film, plate or digital sensor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
133
Q

What is meant by ‘ fogging of the film’?

A

When some photons do not have enough energy to make a useful interaction with the receptor, therefore resultant scatter of photons can degrade the image.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
134
Q

What are the two ways to capture an x-ray image?

A

Film or digital

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
135
Q

What are the two types of film image receptors that can be used?

A
  • direct action film
  • indirect action film
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
136
Q

What are the two types of digital image receptors?

A

-solid state sensor
- photo-stimulate phosphor (PSP)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
137
Q

What image receptor is described:

  • An actual piece of film which is sensitive to x-rays that is wrapped in a packet.
  • used intra-orally, x-ray directly acts on silver halide crystals in film emulsion
A

Direct film

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
138
Q

What image receptor is described:

  • a film inside a cassette which contains intensifying screens, that x-ray photons interact with to produce light photons, exposing the film to produce the image.
  • used extra-orally, light from intensifying screens act on silver halide crystals in film emulsion
A

Indirect film

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
139
Q

What image receptor is described:

Two types of sensors:
- CCD and CMOS
These work by converting light into electrons

A

Solid state sensor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
140
Q

What does CCD stand for?

A

Charge-coupled device

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
141
Q

What does CMOS stand for?

A

Complimentary metal-oxide semiconductor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
142
Q

What image receptor is described:

Latent image produced by the interaction of x-rays with the phosphor layer on the plate, which is then scanned by a laser to produce an image.

A

Phosphor- stimulable phosphor (PSP)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
143
Q

which digital sensor can sometimes not be tolerated well by patients, due to it’s large and bulky nature?

A

Solid state sensors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
144
Q

Which digital sensor has better image resolution?

A

Solid state sensors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
145
Q

What are the two sides of a phosphor plate?

A
  1. Phosphor coating side ( white)
  2. Black side with orientation dot
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
146
Q

which side of a phosphor plate is the image formed on?

A

Phosphor coating side ( white)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
147
Q

what side of the phosphor plate should be visible through the window of a protective bag?

A

The black side

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
148
Q

Describe the stable excited state

A

Image plate placed in patients mouth and phosphor coating is exposed to x-rays which causes a reaction within the phosphor.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
149
Q

Describe the unstable excited state

A

The plate is dropped into the vista scan unit where it is scanned by a red laser

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
150
Q

What type of light is emitted to be differed into an image once the phosphor plate is scanned by red laser?

A

Blue light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
151
Q

What are the 4 layers that make up a charge couple device? And what is their function?

A
  • front cover
  • scintillator layer (converts x-ray energy to light)
  • silicon layer ( converts light into electrical signal)
  • back cover ( incorporates a cable to carry signal to pc)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
152
Q

What is the difference between CCD and CMOS?

A

CMOS - signals sent from each individual cell (pixel)
CDD- signals sent from lines of cells (pixels)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
153
Q

What is the issue with digital images?

A

There is no orientation dot visible on the image. This means you may have images that could be very easy to turn the wrong way and get muddled up.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
154
Q

What type of solid state sensor has higher quality image production?

A

CCD

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
155
Q

Name 6 reasons why digital image receptors would be chosen over film?

A
  1. No chemicals
  2. Faster processing times
  3. Easy archiving
  4. Easy image transfer
  5. Image manipulation
  6. Dose reduction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
156
Q

In regards to the resolution of an image, what happens in response to shorter exposure of image?

A

A drop in image resolution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
157
Q

What size would a pixel be to make an image less detailed?

A

Large

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
158
Q

What happens to exposure if there is too much radiation?

A

High exposure and image appears dark

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
159
Q

What happens to exposure if there is no enough radiation?

A

Low exposure and the image appears pale

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
160
Q

What does PACS stand for?

A

Picture archiving and communication system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
161
Q

What are the different sizes of receptor for digital PSP’s?

A

0,1,2 and 4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
162
Q

What is the one available size of solid state receptor?

A

2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
163
Q

Why might using a size 2 solid state receptor make x-raying anterior teeth difficult?

A

Due to large size of receptor and subsequent positioning in the mouth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
164
Q

What are the two types of biological effects of radiation?

A

Deterministic and non deterministic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
165
Q

Those biological effects that WILL occur are known as?

A

Deterministic effects

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
166
Q

Those biological effects that we know MAY occur are known as?

A

Non deterministic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
167
Q

Which type of biological effect of radiation has a threshold dose? Deterministic or non-deterministic

A

Deterministic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
168
Q

Define somatic effects

A

Those suffered by the exposed person

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
169
Q

What type of deterministic effect can be more aggressive and traumatic, acute or chronic?

A

Acute

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
170
Q

What biological effects of radiation occur at random, due to chance or probability?

A

Non deterministic effects

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
171
Q

Which type of effects are we likely to have in dentistry?

A

Non deterministic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
172
Q

What are the three main factors affecting dose of radiation?

A
  1. Type of radiation
  2. Tissues being irradiated
  3. Age of the patient
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
173
Q

What is the typical effective dose of radiation for bitewings/periapicals?

A

0.0003-0.022 mSv

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
174
Q

What is the dose limit for the public? Value that should not be exceeded

A

1 mSv

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
175
Q

What is the principle used to manage safe dose limits for dental patients?

A

ALARP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
176
Q

What does ALARP stand for?

A

As
Low
As
Reasonably
Practicable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
177
Q

What film speed will reduce the risk of developing fatal malignancy?

A

F speed ( very fast)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
178
Q

The number of “photons” in a beam at a specific place represents…

A

Intensity of x-ray beam

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
179
Q

What is the intensity of radiation proportional to?

A

1/ distance (squared)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
180
Q

What does the size of the controlled area depend on?

A

KV of the x-ray machine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
181
Q

If x-ray machine produces 70kV, what will the size of the controlled area be?

A

1.5m

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
182
Q

What does the plastic barrier wrapped around film do?

A

Protects film from saliva and is good for infection control

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
183
Q

How many layers are there in a direct action film packet?

A

4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
184
Q

What are the 4 layers in a direct action film packet?

A
  1. Outer plastic wrapping
  2. Black paper
  3. Lead foil
  4. Film
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
185
Q

Which layer of direct action film:

Keeps film dry, protects it from fogging and indicates the correct orientation of the film inside the mouth?

A

Outer plastic wrapping

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
186
Q

Why can you only open film packet in a dark room under a safe light?

A

Because radiographic film is photosensitive, which means it will react with light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
187
Q

Which layer of direct action film:

Protects films for light leakage and stiffens/ supports the film to prevent crimp/pressure marks appearing?

A

Black paper

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
188
Q

Which layer of direct action film:

Is composed of a mixture of lead and aluminium, readily absorbs x-rays, prevents back scatter and has a distinct pattern embossed into lead?

A

Lead foil

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
189
Q

Which layer of direct action film:

Is composed of: base layer, adhesive layer (with anti-glare tint), followed by double emulsion layers and gelatin protective layer?

A

Film

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
190
Q

What layer of film reacts with x-rays to form an image?

A

Emulsion layer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
191
Q

What components make up the emulsion layer of film?

A

Silver halide crystals suspended in gelatin

192
Q

What are the two functions of gelatin?

A
  • allows even distribution of crystals
  • absorbs liquid readily to allow processing
193
Q

what is the function of the adhesive layer of film?

A

Sticks the emulsion to the base layer

194
Q

How is a direct action “latent image” formed?

A

X-ray photons hit silver halide crystal emulsion of film. Silver halide crystal becomes sensitised, this is known as the LATENT IMAGE.

195
Q

The pattern produced within the emulsion by the sensitising of silver bromide/iodide crystals, either by light or x-rays.

A

Latent image

196
Q

What is the main reaction involved in creating a latent image?

A

The reduction of the silver bromide crystals to black metallic silver

197
Q

What are the two available speeds of film?

A

Slow and fast

198
Q

What other term can be used for ‘speed of film’?

A

Sensitivity of film to x-rays ( the exposure required to produce a given amount of blackening on an image)

199
Q

What is the effect on film speed, the larger the crystal?

A

The faster the film speed

200
Q

What is the sensitivity of the film dependant upon?

A

The size of crystals in the emulsion

201
Q

If the film speed is fast, is the amount of x-rays required to produce an image higher or lower?

A

Lower

202
Q

How does indirect film differ from direct film?

A

It is sensitive to light rather than x-rays

203
Q

What are the four layers that comprise intensifying screens?

A
  • base layer
  • reflective layer
  • phosphor layer
  • supercoat
204
Q

What material makes up the base layer of intensifying screens?

A

Polyester

205
Q

what is the purpose of the reflective layer of intensifying screens?

A

Reflects light produced back towards film

206
Q

What is the function of the phosphor layer in an intensifying screen?

A

Contains fluorescent phosphors which emit light when excited by X-rays

207
Q

What is the purpose of the super coat layer of intensifying screens?

A

Protects phosphor layer from damage

208
Q

What do intensifying screens allow for?

A

A reduction in exposure and therefore a reduced dose to patient

209
Q

The reduction of the exposed silver bromide crystal to black metallic silver and then making the image permanent is known as?

A

Film processing

210
Q

what are the three methods of film processing?

A
  1. Automatic
  2. Manual
  3. Instant
211
Q

Which type of film processing only tends to be done in emergency situations as it is unreliable?

A

Instant film processing

212
Q

What are the five stages of film processing?

A
  1. Develop
  2. Wash
  3. Fix
  4. Wash
  5. Dry
213
Q

What occurs in the develop stage of film processing?

A

Makes latent image visible

214
Q

What occurs in the two wash stages of film processing?

A
  1. ( after develop stage) Stops development by removing excess developer from film
  2. (after fix stage) Stops fix and removes residual fixer
215
Q

What happens in the fix stage of film processing?

A

Makes image permanent

216
Q

What happens in the dry stage of film processing?

A

Makes film easier to handle and prevents damage

217
Q

What are the two developing agents that act upon silver halide crystals, sensitising them by chemical reduction of silver bromide to silver + bromide?

A

Phenidone and hydroquinone

218
Q

What is the activator within the developer that controls the activity of developing agents?

A

Calcium carbonate

219
Q

What is restrained within the developer that stops the developer working on unexposed crystals?

A

Potassium bromide

220
Q

What is the preservative within the developer that slows down oxidation?

A

Sodium sulphite

221
Q

What is the solvent within the developer that dilutes the chemicals?

A

Water

222
Q

What is very important to note about working temperatures of developers?

A

Each developer has its optimum working temperature

223
Q

What are the three factors that the action of developing agent on silver halide crystals depends on?

A
  1. Time
  2. Temperature
  3. Concentration
224
Q

If the film stays in developer too long, how will it appear?

A

Dark

225
Q

If the film stays in developer too short, how will it appear?

A

Light

226
Q

If the film is too hot, how will it appear?

A

Dark

227
Q

If the film is too cold, how will it appear?

A

Light

228
Q

If the film is too concentrated, how will it appear?

A

Dark

229
Q

If the film isn’t concentrated enough, how will it appear?

A

Light

230
Q

how will silver halide crystals which are developed but not fixed appear?

A

Black

231
Q

What is the role of fixing agents?

A

Change unexposed silver halide to soluble compound so they can be washed away

232
Q

What maintains the pH and neutralises the developer?

A

Acid

233
Q

What are the 5 components of fixer stage of film processing?

A
  1. Clearing agent (ammonium thiosulphate)
  2. Acidifier (acetic acid)
  3. Hardener (aluminium chloride)
  4. Preservative (sodium sulphite)
  5. Solvent (water)
234
Q

What happens to unexposed silver halide crystals during fixing?

A

They are removed

235
Q

How will under-fixed images appear?

A

They will have a green tinge and will not archive well

236
Q

What is the difference between a manual wash and an automatic wash of the film?

A

Manual wash occurs between develop stage and fix stage and then between fix stage and dry stage. Whereas, automatic wash only occurs between fix stage and dry stage.

237
Q

What is the purpose of washing the film?

A

Removes unexposed silver halide crystal once made soluble by fixer

238
Q

What will the effect of insufficient washing do to the film?

A

Make film feel sticky and look cloudy

239
Q

Which method of film processing is the best?

A

Automatic film processing

240
Q

When would instant film processing be beneficial?

A

If you have to process images away from a power source

241
Q

What is the main regulation used for health and safety when carrying out radiographs?

A

COSHH

242
Q

What does COSHH stand for?

A

Control of substances hazardous to health

243
Q

What work act meant that employers has a legal duty to ensure their staffs were safe and risk free at work?

A

HEALTH AND SAFETY AT WORK ACT 1974

244
Q

What must manufactures supply for potential hazardous substances that makes you aware of how dangerous your developer and fixer are?

A

Material safety data sheets

245
Q

What are the key four reasons to take bitewing radiographs?

A
  1. To detect caries
  2. To monitor caries progression
  3. To assess periodontal status
  4. To assess existing restorations
246
Q

What happens in a caries risk assessment?

A

You perform images at regular intervals

247
Q

What are the advantages of horizontal bitewing over vertical?

A

Usually only two images taken whereas verticals require 4 images to be taken

248
Q

What is the advantage of vertical bitewings?

A

They demonstrate more of the roots

249
Q

In a horizontal bitewing, where should the centre of the bite block be placed so to cover the whole region of interest?

A

On the centre of the 6

250
Q

When would you pick a vertical bitewing over a horizontal bitewing?

A

When you need to see more of the root and supporting bone

251
Q

What are the positioning requirements for bitewings?

A
  1. Film and object parallel
  2. Film close to object
  3. X-ray beam perpendicular to object and film
252
Q

How do we achieve good positioning?

A

By always using a holder

253
Q

what could be used as an alternative to film holder if patient cannot tolerate it?

A

Paper tab

254
Q

What does use of a guiding ring ensure?

A

That the x-ray beam is certain to hit the centre of the receptor

255
Q

When may horizontal overlap of teeth be difficult to avoid?

A

If there is crowding or tilting of teeth

256
Q

When would horizontal overlap of teeth be deemed acceptable?

A

If less than half of enamel is superimposed

257
Q

What are the two problems associated with vertical angulation of x-ray beam to receptor?

A
  1. Upper bone levels will be projected off the receptor
  2. Resultant distortion of the teeth has caused separation of the cusps
258
Q

On a bitewing, where does the ‘dot’ on the receptor go?

A

Always to the palate

259
Q

If a child refuses to cooperate with bitewings what is the alternative?

A

Lateral oblique mandible images

260
Q

what can reduce the dose of radiation to patients by up to 50%?

A

Use of rectangular collimation

261
Q

Why is legislation for radiology necessary?

A

Helps to minimise risks from radiation exposure

262
Q

What regulations concern equipment and the protection of staff and the general public?

A

IRR17

263
Q

What regulations are aimed primarily at the protection of patients?

A

IR(ME)R 17

264
Q

What was the necessary regulations in place before the updated IRR17?

A

IRR99

265
Q

When would you consult your radiation protection advisor (RPA)?

A

If planning set up of a new surgery, or when radiation is over dose

266
Q

What does IR(ME)R stand for?

A

Ionising radiation ( medical exposures) regulations

267
Q

What are the four roles in radiography?

A
  1. Employer
  2. Referrer
  3. Practitioner
  4. Operator
268
Q

Who entitles staff in various roles to undertake roles involved in IR(ME)R?

A

Employers

269
Q

What is the selection of a radiograph based upon?

A

Patients history and examination

270
Q

What is choice of radiograph based on?

A

The prevalence of the disease, rate of progression and diagnostic accuracy of imaging technique

271
Q

What is the purpose of selection criteria?

A

Helps to overcome the wide variation in practice and minimise or prevent any inappropriate radiographic examinations

272
Q

Who is ‘the referrer’?

A

A registered dental practitioner who is entitled in accordance with the employers procedures to refer individuals for medical exposure to a practitioner

273
Q

Which member of the dental team has limited entitlement as an “operator”?

A

Dental nurse

274
Q

Who can take radiographs in general dental practice?

A
  • a dentist
  • a dental hygienist or therapist
  • a suitably qualified dental nurse
  • a clinical dental technician
275
Q

what does the “operator” do?

A

Takes radiographs

276
Q

Clinical evaluation of each exposure must take place. What is clinical evaluation?

A

Interpretation of the outcome and implications of, and the information resulting from, a medical exposure

277
Q

What is the relationship between the practitioner and the operator?

A

Shall co-operate, regarding practical aspects, with other specialists and staff involved in a medical exposure, as appropriate

278
Q

How often should x-ray units be tested?

A

Preferably annually but minimum of every 3 years

279
Q

What are the optimum viewing condition for diagnosing caries using a radiograph?

A

Low ambient light and a bright screen limited to area of image

280
Q

Why do we get ‘cervical burnout’?

A

The x-ray photons over-penetrate or burn out the thinner tooth edge and create the radiolucent area that mimics cervical caries

281
Q

How often should a high risk child receive an intra-oral radiograph?

A

6 monthly

282
Q

How often should a moderate risk child receive an intra-oral radiograph?

A

Annually

283
Q

How often should a low risk child receive an intra-oral radiograph?

A

12-18 months (deciduous teeth)
24 months or more (permanent teeth)

284
Q

The supportive and connective tissue element which form in cancellous bone

A

Trabecula

285
Q

What is the trabecula pattern?

A

Course of stress lines along the bone and maximum trabeculae develop along the lines of maximum stress

286
Q

what type of trabecula pattern does the mandible have?

A

Thick, close together, horizontally aligned

287
Q

what type of trabecula pattern does the maxilla have?

A

Finer, more widely spaced, no obvious alignment pattern

288
Q

The three most important features to look at when assessing if there is peri-radicular disease on a radiograph, are?

A
  • radiolucent line representing the periodontal ligament space
  • radioopaque line representing lamina dura
  • trabecula pattern and density of surrounding bone
289
Q

What is the radiographic appearance of initial acute inflammation in periapical pathology?

A
  • no apparent changes
    OR
  • possible widening of PDL
290
Q

What is the radiographic appearance of initial spread of inflammation in periapical pathology?

A

Loss of lamina dura at apex

291
Q

What is the radiographic appearance of further inflammatory spread in periapical pathology?

A

Periapical bone loss

292
Q

What is the radiographic appearance of initial chronic inflammation in periapical pathology?

A
  • No bone destruction seen
    OR
  • dense sclerotic bone periapically (sclerosing osteitis)
293
Q

What is the radiographic appearance of chronic, long standing, inflammation in periapical pathology?

A
  • circumscribed, well defined, radiolucent area periapically with sclerotic bone surrounding
294
Q

What is the radiolucency found in radiographs showing chronic inflammation of periapical pathology also described as?

A

Rarefying osteitis

295
Q

What is quality assurance?

A

An organised effort by staff to ensure that the diagnostic images produced are of sufficiently high quality to consistently provide adequate diagnostic information at the lowest possible cost and the least possible exposure to the patient

296
Q

What does SOP stand for?

A

Standard operating procedures

297
Q

What are the 6 components of a quality assurance programme?

A
  • image quality
  • x-ray equipment
  • processing
  • working procedures
  • training
  • audit
298
Q

What two ways can an image be audited to ensure high quality?

A
  1. Image quality rating system
  2. Film reject analysis
299
Q

How could image quality rating systems grade images?

A
  • rating diagnostically acceptable (A) or diagnostically not acceptable (N)
    OR
  • rated either 1,2 or 3
300
Q

What image would be given an image quality rating of 1:

  • excellent
  • diagnostically acceptable
  • diagnostically unacceptable
A

Excellent

301
Q

What image would be given an image quality rating of 3:

  • excellent
  • diagnostically unacceptable
  • diagnostically acceptable
A

Diagnostically unacceptable

302
Q

What image would be given an image quality rating of 2:

  • diagnostically acceptable
  • excellent
  • diagnostically unacceptable
A

Diagnostically acceptable

303
Q

what method in radiology can be used to measure exhaustion of the developer?

A

Sensitometry

304
Q

What type of image would signify an exhausted developer?

A

A pale image

305
Q

What is a step-wedge?

A

A radiographic phantom made from differing thicknesses of metal

306
Q

What are the three most common problems faced during film processing?

A
  • poor handling
  • insufficient training
  • light exposure
307
Q

If a film is exposed to too much light during processing what will be the consequence?

A

Fogging of the film

308
Q

What test can be used to monitor darkroom safelight conditions?

A

The coin test

309
Q

What is a safelight?

A

A light with a coloured filter that can be used in a darkroom without affecting photosensitive film or paper

310
Q

What are the four reasons why a radiographic image may appear very pale?

A
  • wrong exposure selection ( underexposed image)
  • not enough time in the developer
  • developer temperature too low
  • incorrect dilution of developer
311
Q

Why might part of a film appear fogged?

A
  • light leakage in darkroom
  • incorrect handling of film
  • patient movement
312
Q

What would cause a film to turn green/yellow?

A

Insufficient fixing during processing, involving time, temperature and dilution.

313
Q

What would be the cause of a film presenting with marks that resemble a lightening strike or a tree?

A

Caused by static electricity discharge, it is the result of pulling film too quickly out of packet in a dry atmosphere

314
Q

Which three extra-oral images relating to the mandible are regularly seen?

A
  1. posterior-anterior mandible
  2. Lateral oblique of mandible
  3. DPT
315
Q

Which three extra-oral images relating to the maxilla and cranium are regularly seen?

A
  1. Lateral cephalogram (skull)
  2. Occipito-mental views (face)
  3. Sailography
316
Q

What does an ‘oblique’ angle mean?

A

Neither parallel nor at right angles to a specified or implies line: slanting

317
Q

What does ‘PA’ stand for?

A

Postero-anterior

318
Q

What does ‘AP’ stand for?

A

Antero-posterior

319
Q

What does ‘OM’ stand for?

A

Occipito-mental

320
Q

What are positioning landmarks?

A

A series of imaginary lines on the side of a patient’s face which are used to help position a patient for extra-oral radiography

321
Q

Name the three main positioning landmarks

A
  1. Radiographic base line
  2. Frankfort plane
  3. Maxillary occlusal plane
322
Q

Which positioning landmark matches the description below?

Line from outer canthus of the eye to the external auditory meatus, representing the base of the skull.

A

Radiographic base line

323
Q

Which positioning landmark matches the description below?

Line from the ala of the nose to the tragus of the ear. This landmark is used a lot in cone beam CT.

A

Maxillary occlusal plane

324
Q

Which positioning landmark matches the description below?

Line from the inferior orbital border to the upper border of the external acoustic meatus. Can also be known as the anthropological base line.

A

Frankfort plane

325
Q

which positioning landmark is most often used when taking a DPT?

A

Frankfort plane

326
Q

What are the components of equipment required for an extra-oral radiograph to be taken?

A
  1. Skull unit or cephalometric unit
  2. Image receptor
  3. Anti-scatter grid
  4. Lateral cephalogram unit
327
Q

what does scatter of x-ray photons do to the final image?

A

Degrade or fog the image

328
Q

What is an anti-scatter grid?

A

A grid made up of narrow strips of lead alternating with plastic, which limits the amount of scattered radiation reaching the detector/film

329
Q

Why might a PA mandible be requested?

A

To look for potential fractures, cysts or malignancy causing medio-lateral displacement, expansion to bone destruction.

330
Q

what extra oral radiograph is a PA mandible almost always requested alongside?

A

A DPT

331
Q

What are the two main advantages of having a PA mandible taken over other extra-oral views?

A
  • reduced magnification of facial structures on receptor
  • reduced dose of radiation to eyes
332
Q

How would a patient be positioned in regards to equipment if a PA mandible is to be taken?

A
  • patient faces film
  • nose and forehead touch film holder
  • radiographic baseline should be 90 degrees to film
333
Q

How do we find the ‘mid-line’ of the patient anteriorly and posteriorly?

A

Anterior: generally between the eyes
Posterior: at the external occipital protuberance

334
Q

Why would we not just take a lateral mandible to visualise the mandible?

A

Because the two halves of the mandible will be superimposed

335
Q

what way should you oblique the mandible in order to achieve full separation of the rami on the radiograph?

A

Oblique in the vertical plane

336
Q

what are the indications for taking a lateral oblique mandible?

A
  • fracture
  • pathology
  • assessment of wisdom teeth
  • dental assessment in special needs patients
  • caries in children who can’t tolerate bitewing
337
Q

What are the two techniques used to take lateral oblique mandibles?

A
  1. Isocentric positioning using a skull unit
  2. Dental tube with either vertical or horizontal angulation
338
Q

What is an isocentric technique?

A

Where all beams used in a radiation treatment have a common focus point, a.k.a the isocenter

339
Q

What extra- oral view can be tricky to take on individuals with broad shoulders and why?

A

Isocentric view,
The skull unit is required to be angled at 25 degrees so that the x-ray tube moves towards the patients shoulder. If shoulders are broad they can get in the way of the beam.

340
Q

What are the two disadvantages of vertical angulation of the dental tube when taking lateral oblique mandibles?

A
  1. Angulation can cause vertical distortion of the teeth
  2. Maxillary teeth are not always shown clearly
341
Q

What angulation of the dental tube is most common when taking a lateral oblique mandible?
Horizontal or vertical?

A

Horizontal

342
Q

Which angulation of the dental tube when taking a lateral oblique mandible, aims through the radiographic keyhole?
Vertical or horizontal?

A

Horizontal

343
Q

what is the radiographic keyhole?

A

The triangular space between the back of the ramus and the cervical spine

344
Q

What is the disadvantage of horizontal angulation of the dental tube when taking lateral oblique mandibles?

A

X-ray beam may not pass directly between the contact points of the teeth therefore causing them to be overlapped on the film

345
Q

What is a standardised and reproducible form of skull radiography in orthodontics, to assess the relationship of the teeth to the jaws, and the jaws to the rest of the facial skeleton?

A

Cephalometric radiography

346
Q

What are the two main indications of cephalometric radiography?

A
  1. Orthodontic assessment
  2. Pre-orthodontic surgery
347
Q

In a lateral ceph where is the x-ray beam aimed?

A

At the external acoustic meatus

348
Q

what is a thyroid shield and what is it used for?

A

Lead collar that wraps around your neck to block the radiation that’s generated when taking a radiograph

349
Q

What does a magnification rod, found in ceph films, allow for and why is it necessary?

A

Allows for the calculation of any magnification that has occurred on the final image and is necessary for surgical planning

350
Q

The exposure required to penetrate a lateral face/skull is so great, in normal circumstances the beam would not be attenuated at all by the soft tissues, so they would not be visible on the image. What can be used to overcome this and allow soft tissues to be visualised on a lateral ceph?

A

An aluminium filter

351
Q

What are the main indications for x-raying facial bones?

A
  • trauma and suspected fracture
  • pathology
352
Q

what are the most common fractures to the facial bone?

A

Zygoma, le fort and orbital blowout

353
Q

what are the three different angles of occipito-mental views used to view different areas of complex facial bone anatomy?

A
  • OM 0 degrees
  • OM 10 degrees
  • OM 30 degrees
354
Q

What view is taken for imaging of facial bones?

A

Occipito-mental views

355
Q

What should the radiographic baseline to film angle be for OM views?

A

45 degrees to film

356
Q

What is caudal angulation?

A

How you would raise the x-ray tube to angle the central ray

357
Q

What are the two main benefits of increasing angulation on OM views?

A
  1. Projects dense bones of skull base down and away from facial structures
  2. Improves view of zygomatic arch
358
Q

when wanting to visualise the zygomatic arches, which OM view is the best to use?

A

OM 30 degrees

359
Q

What does a star on a radiographic image indicate?

A

There is a fracture indicated by radiographer who took image.

360
Q

what is a tomogram?

A

A radiograph showing a slice or section of tissue in focus

361
Q

What is a form of tomography used in dentistry?

A

DPT

362
Q

Only structures within what area/slice are sharp on a DPT image?

A

The focal trough

363
Q

what shape is the focal trough?

A

Horse-shoe shaped

364
Q

what are the three disadvantages of intensifying screens within conventional film cassettes?

A
  1. Light is emitted in all directions
  2. Light affects larger area of film than a single photon
  3. Image quality (fine detail) is not as good as direct action film
365
Q

When taking a DPT, what does use of a bite peg do?

A
  • Forces patient into edge-to-edge occlusion
  • positions both arches in focal trough
366
Q

what are the main advantages to taking a DPT over a periapical?

A
  1. Can capture entire dentition in once image
  2. Able to image non-dental areas
  3. Lack of intra-oral holders benefits some patients
367
Q

What are some key clinical indications for taking a DPT?

A
  • orthodontic assessment
  • mandibular fractures
  • degenerate disease of TMJ
  • implant planning or review
  • symptomatic third molars
368
Q

What are the main disadvantages of taking a DPT over a periapical?

A
  • lack of fine detail
  • superimposition
  • more artefacts
  • patient co-operation required
  • exposure time up to 16 seconds
  • higher radiation dose per image
369
Q

describe the patients position when taking a DPT

A
  1. Stands with spine straight, holding handles
  2. Bites incisors edge to edge on bite block
  3. Head immobilised
  4. Tongue to roof of mouth
  5. Stand still
  6. Do not talk or swallow
370
Q

Why should we not routinely use lead aprons in dental radiography?

A

Because they do not protect from internal scatter and they interfere with image as can be projected onto image and may also catch the tube as it rotates

371
Q

What is an example dose of radiation from a DPT?

A

3.85-30 micro Sv

372
Q

what are ghost images?

A

Images of a structure on one side which are projected onto other side

373
Q

why are ghost images always seen at a higher level than the real structure?

A

Because the x-ray beam is pointing upwards at an angle of 8 degrees to the horizontal

374
Q

what incisors relationship does not allow for a patient to correctly bite upon a bite block?

A

Class III incisal relationship- where mandibular incisor is anterior to maxillary incisor

375
Q

What does ‘collimated’ mean?

A

To make parallel

376
Q

When a patient has a strong gag reflex, what radiograph is most likely to be taken?

A

DPT

377
Q

Why is superimposition not as bad in intra-oral x-rays compared to extra-oral x-rays?

A

As intra-oral x-ray source and receptor can both be placed close to area of interest ( therefore fewer structures are captured, less superimposition)

378
Q

What form of radiography try to counteract superimposition?

A

Tomography

379
Q

what type of tomography, involving multiple slices is commonly used in medicine?

A

Computed tomography

380
Q

What type of tomography is a Panoramic radiograph?

A

Conventional tomography

381
Q

Where is the x-ray source in comparison to the patient during a DPT?

A

Behind

382
Q

Where is the receptor in comparison to the patient during a DPT?

A

In front

383
Q

Describe the characteristics of an x-ray beam used for DPT

A

Narrow, vertical, “fan-shaped”

384
Q

why is it common for the incisor region to appear blurry on a DPT?

A

Because the focal trough is thinner in this region

385
Q

What does “orthogonal” view mean?

A

A 90 degree view horizontally or vertically

386
Q

What are the advantages of the x-ray beam angulation being changed to a more orthogonal view in order to visualise teeth?

A
  • reduces overlap of the teeth to aid assessment of approximal caries (particularly improves premolars)
  • improves angulation to better represent interdental periodontal bone levels
387
Q

What are the disadvantages of the x-ray beam angulation being changed to a more orthogonal view in order to visualise teeth?

A
  • distorts the rest of skeleton
  • typically a narrower field of view so may miss condyles on edge of image
388
Q

How much is the image within the focal trough magnifies by?

A

Around 25%

389
Q

Which structures in relation to the focal trough are more magnified?

Lingual or buccal

A

Lingual

390
Q

Which structures in relation to the focal trough are less magnified?

Lingual or buccal

A

Buccal

391
Q

How do teeth positioned buccal to the focal trough appear on an image?

A

Narrower (vertical magnification)

392
Q

How do teeth positioned lingual l to the focal trough appear on an image?

A

Broader (horizontal magnification)

393
Q

Why are structures within the focal trough not distorted?

A

Because the degree of horizontal magnification matches that vertically

394
Q

Where is the x-ray source positioned in comparison to the focal trough?

A

Lingually

395
Q

By how many times is the radiation dose greater per DPT image compared to periapical image?

A

5 times

396
Q

What is the ‘field limitation’?

A

Changing size of x-ray field to reduce radiation does

397
Q

What are the three light beam markers used to take DPT?

A
  • horizontal line: Frankfort plane
  • vertical mid-line: mid-sagittal plane
  • vertical canine lines
398
Q

If the Frankfort plane is out of position due to the chin of the patient being down, how will this reflect on the image?

A

The occlusal plane will appear ‘smiling’

399
Q

If the Frankfort plane is out of position due to the chin of the patient being up, how will this reflect on the image?

A

“Flat” occlusal plane

400
Q

If the mid-sagittal plane is not centered, how will this reflect on the image?

A

Distortion of one/both sides of image

401
Q

If the mid-sagittal plane is out of position due to incorrect vertical alignment, how will this reflect on the image?

A

Distortion and occlusal plane cant

402
Q

If the mid-sagittal plane is out of position due to the patient being slumped over, how will this reflect on the image?

A

Excessive cervical spine shadow

403
Q

If patient does not press tongue against palate while DPT is being taken, how will this reflect on the image and why?

A

A black radiolucent band across the maxilla will appear as an air gap has been created between the tongue and roof of mouth

404
Q

What are the 6 different structures that make up the mandible and can be seen clearly on a DPT?

A
  • condyle
  • coronoid process
  • sigmoid notch
  • ramus
  • angle
  • body
405
Q

How does the submandibular fossa present on a radiograph?

A

As a depression on the lingual aspect of the body of the mandible

406
Q

Why does the mastoid process sometimes appear as having a ‘honeycomb’ pattern on a radiograph?

A

Because it is filled with trabecular bone

407
Q

What is the purpose of the articular eminence?

A

Stops condylar head from moving forward out of the glenoid fossa

408
Q

Why are misleading shadows created on DPT’s?

A

Due to the rotational technique, the resulting panoramic image also exhibits abnormal structures

409
Q

What are the two types of misleading shadow?

A
  1. Double shadows
  2. Ghost shadows
410
Q

What are double shadows and how are they created?

A

Created by structures located near the centre of rotation which, due to their central position, are captured twice (i.e. x-ray machine passes through them twice as it spins round head)

411
Q

what three anatomical structures commonly have a double shadow?

A
  1. Hyoid bone
  2. Soft palate
  3. Cervical spine
412
Q

What are ghost shadows and why are they created?

A

Structures on one side are projected onto the other side. Created by structures between the x-ray source and the centre of rotation

413
Q

Why do ghost shadows always appear higher than where the structure should actually be?

A

Due to the inclination of the x-ray beam and that it is transposed on to the opposite side of the true anatomical position

414
Q

Why are DPT’s poor for showing anterior fractures of the mandible?

A

Due to superimposition of ghost shadow of cervical spine

415
Q

What type of radiographic image can be created which cuts out areas we aren’t interested in and therefore less anatomical areas are radiated?

A

Panoramic pseudo-bitewing image

416
Q

What scale is used to quantitively measure radio-density on CT scans?

A

Hounsfield scale

417
Q

What is a “voxel”?

A

Volume of pixel

418
Q

What does orthognathic assessment/surgery mean, in simpler terms?

A

Jaw assessment/surgery

419
Q

What are the 7 main indications for use of a CT scan?

A
  1. Intracranial assessment
  2. Trauma
  3. Evaluation of osseous lesions
  4. Salivary gland assessment
  5. Cancer screening
  6. Orthognathic assessment
  7. Implant planning
420
Q

What is Dentascan?

A

A specialised CT scan of the mandible or maxilla often done before placement of dental implants

421
Q

What is the main indication for using CBCT over CT?

A

CBCT has a much lower radiation dose than medical grade CT

422
Q

What does CBCT stand for?

A

Cone-beam computer tomography

423
Q

Prior to a CBCT scan being performed, an initial positioning view is usually taken. Why is this?

A

This ensures that the area of concern is in the field of view

424
Q

For a CBCT, are the x-ray tube and flat panel receptor rotating in different directions or the same direction?

A

Same direction

425
Q

In a CBCT scan which x-ray component sends the information to the computer where an image will be produced?

A

Receptor

426
Q

For CBCT, if multi-planar imaging is available, what are the three slices that will be displayed?

A
  1. Axial
  2. Coronal
  3. Sagittal
427
Q

What are the four main indications for taking a CBCT?

A
  1. Localisation of unerupted tooth
  2. Assessment of resorption from unerupted tooth
  3. Cleft palate
  4. Orthognathic surgery assessment
428
Q

What field of vision should dental practices use?

A

Small

429
Q

What does the unit mA stand for and what does it represent?

A

Milliamperes, represents the amount of current passed through the x-ray tube

430
Q

What is spatial resolution?

A

The number of pixels utilised in construction of an image

431
Q

What does field of view mean (FOV)?

A

The open, observable area a person can see through their eyes or via an optical device, such as a camera

432
Q

what is the benefit of taking an I-CAT panoramic scan?

A

Allows you to take complete 3D images at a radiation dose comparable to a 2D panoramic image

433
Q

What are 4 imaging modalities that are hardly, if ever, used in general dental practices, however hospital dental specialists may request them?

A
  1. MRI
  2. Ultrasound
  3. Nuclear medicine (radio-isotope scanning)
  4. PET
434
Q

What is a blow-out fracture?

A

Fracture of the orbital floor, causing orbital contents to herniate into the sinus

435
Q

What is the main benefit and also the mian disadvantage to a smaller CBCT voxel being used?

A

Benefit: results in a higher resolution image
Disadvantage: requires longer scan time and therefore a higher dose required

436
Q

What is the axial plane?

A

Also known as the transverse plane, it is a horizontal plane that divides the body part into superior and inferior sections

437
Q

What is the coronal plane?

A

Also known as frontal plane, it divides the body part into front and back sections

438
Q

What is the sagittal plane?

A

Also known as the longitudinal plane, it divides the body into right and left sections

439
Q

What is MRI?

A

Magnetic resonance screening is a type of scan that uses strong magnetic fields and radio waves to produce detailed images of the inside of the body

440
Q

what type of tissue is MRI useful for assessing?

A

Soft tissue

441
Q

What are the main contraindications of MRI use?

A
  • pacemakers
  • artificial heart valves
    -intra-cerebral aneurysm clips
  • 1st trimester pregnancy
  • claustrophobia
442
Q

In what patient cases would it be suitable to refer for MRI?

A
  • TMJ disorders (particularly disc problems)
  • salivary gland pathology
  • assessing early bone changes if there is suspected medication-related osteonecrosis of the jaw
443
Q

how does an ultrasound work?

A
  1. Transducer placed o skin
  2. Sound waves bounce off tissues and back to probe
444
Q

Ultrasound can travel beyond hard tissues. True or false?

A

False

445
Q

what is radio-isotope scanning?

A

An imaging technique where small dose of isotopes are injected into the body and emit radiation in order to detect changes in target tissue

446
Q

what is technetium?

A

The lightest chemical element whose isotopes are all radioactive

447
Q

what chemical element foes radioisotope scanning use?

A

Technetium

448
Q

what is a PET CT scan?

A

Position emission tomography combined with CT

449
Q

When would a PET CT scan be used?

A

To diagnose and stage cancer

450
Q

Who discovered x-rays?

A

Wilhelm Conrad Roentgen

451
Q

What year were x-rays discovered?

A

1895

452
Q

Name the law that gives us the safe distance from a source of x-rays

A

Inverse square law

453
Q

What does the photoelectric effect do?

A

The emission of electrons when light shines on a material

454
Q

What does IR(ME)R 2000 stand for?

A

Ionising radiation (medical exposure) regulations 2000

455
Q

what does IRR 2017 stand for?

A

Ionising radiation regulations 2017

456
Q

How does IRMER 2017 differ from IRR 2017?

A

IRMER 2017 deals with exposure to patients for medical and non-medical procedures, whereas IRR 2017 deals with exposure to employees and the public

457
Q

What does RPA stand for? And what do they do?

A

Radiation protection advisor, is an individual or body that advises on compliance with the IRRs

458
Q

What does RPS stand for? And what do they do?

A

Radiation protection supervisor, a person/s appointed for the purpose of securing compliance with the IRRs in respect to work carried out in an area which is subject to local rules

459
Q

Name the 4 designated roles under IR(ME)R 2017

A
  1. Employer
  2. Referrer
  3. Practitioner
  4. Operator
460
Q

Which designated role in IRMER deals with legalities of taking x-rays?

A

Employer

461
Q

What is the designated role of the practitioner under IRMER 2017?

A

Justifies the exposure

462
Q

Who is the “operator” according to IRMER 2017?

A

Any person involved in the “practical aspects” of the production of a radiograph.

463
Q

what are local rules?

A

Written rules pertaining to controlled areas where the appropriate procedures are to be followed and responses to incidents or accidents involving ionising radiation.

464
Q

What does MPE stand for?

A

Medical Physics Expert

465
Q

what is the role of an MPE?

A

Responsible for carrying out dose audits to ensure that dose optimisation and risk education is being correctly achieved

466
Q

What is the duty of the employer regarding selection criteria for radiographs?

A

Shall establish recommendations concerning referral criteria

467
Q

What are the three main advantages of using the paralleling technique for intra-oral radiographs?

A
  1. Allows accurate geometry of image
  2. Rectangular collimator is easier to position
  3. Can reduce dose to patient by reducing repeats and does not expose patients fingers
468
Q

What age of patient is more radiosensitive? 0-18 or 50 +. And why?

A

0-18, because young patients have more dividing cells and a longer lifespan over which to develop effect

469
Q

What are the two main roles of the “employer”?

A
  1. Establishing QA programmes for standard operating procedures
  2. Ensuring that every practitioner undertakes CPD
470
Q

How much CPD must every practitioner or operator prove that they have undergone every 5 years?

A

5 hours

471
Q

What are the tow recommended radiographic techniques for diagnosing caries?

A

Horizontal bitewings ( gold standard)
Paralleling periapicals

472
Q

What are the two disadvantages of taking a lateral oblique mandible?

A
  1. Angulation can cause vertical distortion of teeth
  2. Maxillary teeth are not always shown clearly
473
Q

what type of radiograph requires a thyroid shield for lead protection as the exposure factors required and consequent dose are slightly greater?

A

Lateral cephalogram

474
Q

What filter is used in a lateral cephalogram to allow visualisation of bone and soft tissue on the film?

A

Aluminium filter

475
Q

what was the ‘three tier approach’ that IRR17 introduced that IRR99 did not have?

A
  1. Notification
  2. Registration
  3. Licensing
476
Q

How do RPA and MPE differ?

A

RPA has a role in IRR17, MPE is part of IRMER17 ( though could be the same person!)

Dentistry Module 4 (20 decks)

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