Image Receptors Flashcards

1
Q

The item the x-ray image is formed on

A

Image receptor

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2
Q

Give three examples of image receptors

A

Film, plate or digital sensor

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3
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.

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4
Q

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

A

Film or digital

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5
Q

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

A

direct action film
indirect action film

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6
Q

What are the two types of digital image receptors?

A

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

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7
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

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8
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

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9
Q

What image receptor is described:

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

A

Solid state sensor

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10
Q

What does CCD stand for?

A

Charge-coupled device

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11
Q

What does CMOS stand for?

A

Complimentary metal-oxide semiconductor

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12
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)

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13
Q

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

A

Solid state sensors

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14
Q

Which digital sensor has better image resolution?

A

Solid state sensors

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15
Q

What are the two sides of a phosphor plate?

A

Phosphor coating side ( white)

Black side with orientation dot

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16
Q

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

A

Phosphor coating side ( white)

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17
Q

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

A

The black side

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18
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.

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19
Q

Describe the unstable excited state

A

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

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20
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

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21
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)

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22
Q

What is a ‘pixel’?

A

Electrons within each cell

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23
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)

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24
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 east to turn the wrong way and get muddled up.

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25
Q

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

A

CCD

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26
Q

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

A

No chemicals
Faster processing times
Easy archiving
Easy image transfer
Image manipulation
Dose reduction

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27
Q

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

A

A drop in image resolution

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28
Q

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

A

Large

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29
Q

What happens to exposure if there is too much radiation?

A

High exposure and image appears dark

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30
Q

What happens to exposure if there is not enough radiation?

A

Low exposure and the image appears pale

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31
Q

What does PACS stand for?

A

Picture archiving and communication system

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32
Q

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

A

0,1,2 and 4

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33
Q

What is the one available size of solid state receptor?

A

2

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34
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

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35
Q

What does the plastic barrier wrapped around film do?

A

Protects film from saliva and is good for infection control

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36
Q

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

A

4

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37
Q

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

A

Outer plastic wrapping
Block paper
Lead foil
Film

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38
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

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39
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

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40
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

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41
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

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42
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

43
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

44
Q

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

A

Emulsion layer

45
Q

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

A

Emulsion layer

46
Q

What components make up the emulsion layer of film?

A

Silver halide crystals suspended in gelatin

47
Q

What are the two functions of gelatin?

A

allows even distribution of crystals
absorbs liquid readily to allow processing

48
Q

what is the function of the adhesive layer of film?

A

Sticks the emulsion to the base layer

49
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.

50
Q

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

A

Latent image

51
Q

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

A

The reduction of the silver bromide crystals to black metallic silver

52
Q

What are the two available speeds of film?

A

Slow and fast

53
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)

54
Q

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

A

The faster the film speed

55
Q

What is the sensitivity of the film dependant upon?

A

The size of crystals in the emulsion

56
Q

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

A

Lower

57
Q

How does indirect film differ from direct film?

A

It is sensitive to light rather than x-rays

58
Q

What are the four layers that comprise intensifying screens?

A

base layer
reflective layer
phosphor layer
supercoat

59
Q

What material makes up the base layer of intensifying screens?

A

Polyester

60
Q

What material makes up the base layer of intensifying screens?

A

Polyester

61
Q

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

A

Reflects light produced back towards film

62
Q

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

A

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

63
Q

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

A

Protects phosphor layer from damage

64
Q

What do intensifying screens allow for?

A

A reduction in exposure and therefore a reduced dose to patient

65
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

66
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

67
Q

what are the three methods of film processing?

A

Automatic
Manual
Instant

68
Q

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

A

Instant film processing

69
Q

What are the five stages of film processing?

A

Develop
Wash
Fix
Wash
Dry

70
Q

What occurs in the develop stage of film processing?

A

Makes latent image visible

71
Q

What occurs in the two wash stages of film processing?

A

( after develop stage) Stops development by removing excess developer from film
(after fix stage) Stops fix and removes residual fixer

72
Q

What happens in the fix stage of film processing?

A

Makes image permanent

73
Q

What happens in the dry stage of film processing?

A

Makes film easier to handle and prevents damage

74
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

75
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

76
Q

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

A

Calcium carbonate

77
Q

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

A

Potassium bromide

78
Q

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

A

Sodium sulphite

79
Q

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

A

Water

80
Q

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

A

Each developer has its optimum working temperature

81
Q

What is the action of the developing agent on silver halide crystals dependent on?

A

Time
Temperature
Concentration

82
Q

What is the action of the developing agent on silver halide crystals dependent on?

A

Time
Temperature
Concentration

83
Q

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

A

Dark

84
Q

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

A

Light

85
Q

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

A

Dark

86
Q

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

A

Light

87
Q

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

A

Dark

88
Q

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

A

Light

89
Q

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

A

Black

90
Q

What is the role of fixing agents?

A

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

91
Q

What maintains the pH and neutralises the developer?

A

Acid

92
Q

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

A

Clearing agent (ammonium thiosulphate)
Acidifier (acetic acid)
Hardener (aluminium chloride)
Preservative (sodium sulphite)
Solvent (water)

93
Q

What happens to unexposed silver halide crystals during fixing?

A

They are removed

94
Q

How will under-fixed images appear?

A

They will have a green tinge and will not archive well

95
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.

96
Q

What is the purpose of washing the film?

A

Removes unexposed silver halide crystal once made soluble by fixer

97
Q

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

A

Make film feel sticky and look cloudy

98
Q

Which method of film processing is the best?

A

Automatic film processing

99
Q

When would instant film processing be beneficial?

A

If you have to process images away from a power source

100
Q

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

A

COSHH

101
Q

What does COSHH stand for?

A

Control of substances hazardous to health

102
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

103
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