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RAD > RAD03-2005 - How do you create an X-ray image? > Flashcards

RAD03-2005 - How do you create an X-ray image? Flashcards

1
Q

What re the two types of radiographic film?

A

Direct action for intra-oral radiography

Indirect action used in conjunction with 2 intensifying screens inside an extra-oral cassette

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2
Q

Why are DA films packed in plastic?

A

For infection control reasons

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3
Q

How many DA sizes are available?

A

3

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4
Q

What are the 3 DA sizes available?

A

22x35mm for anterior periodical and children’s bitewing
31x41mm for posterior periodical and adult bitewings
57x76mm for occlusals

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5
Q

What are the contents of the DA film packet?

A

Clear plastic barrier envelope
Outer plastic wrapper that is white an colour coded
Plastic film with an embossed dot in one corner for orientation
Black paper either side of the film
Thin sheet of lead foil

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6
Q

What is the emulsion present in DA film?

A

Silver halide solution

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7
Q

Why must the DA film be opened in the dark?

A

Emulsion is light sensitive

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8
Q

What is the silver halide emulsion protected by?

A

gelatin

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9
Q

What is present behind the film?

A

Lead foil

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10
Q

What is the purpose of lead foil behind the film?

A

Prevent residual radiation passing through the patient

Prevents scattered photons coming back, hitting film and degrading the image

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11
Q

What is the intra-oral film that contains and special sachet and tabs called?

A

Instant process/ self-developing

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12
Q

What does the special sachet of the instant process intra oral film contain?

A

Developer and fixer

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13
Q

What are the advantages of the instant process intra-oral film of standard DA?

A

No dark room or processing facilities are required

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14
Q

What are the disadvantages of the instant process intra-oral film of standard DA?

A

Poor image quality and no protective lead foil

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15
Q

How does the silver halide of the indirect film differ to that of direct film?

A

Siver halide emulsion in indirect film is not sensitive to X-rays but various colours of light

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16
Q

What must be used alongside indirect films?

A

Intensifying screens emitting the correct light colour

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17
Q

What replaces orientation embossed dots on indirect films?

A

R and L metal letters

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18
Q

What do intensifying screens consist of?

A

fluorescent phosphors embedded in a plastic matrix that emit light when hit by x-rays

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19
Q

What do fluorescent phosphors include?

A

Calcium tungstate (blue)
Rare earth materials (green)
yttrium

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20
Q

Why must the intensifying screens be close to the film?

A

light diverges more if there is a gap and the image will be blurred

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21
Q

Why does ultraviolet light lead to a sharper resolution?

A

Very little cross over effect

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22
Q

What is the benefit of the intensifying screens to the patient?

A

Reduce the number of photons required to produce an image so the dose is reduced

23
Q

What is the advantage of using rare earth type screens?

A

the initial amount of x-rays required to generate the light is considerably less than with the calcium tungstate, so the dose to the patient can be reduced further

24
Q

Why must intensifying screens be kept clean?

A

Marks of screen will prevent emitted light from hitting the film

25
Q

What does the cassette consist of?

A

Light-tight aluminium/ carbon fibre

26
Q

What is chemical processing?

A

The events required to converted the so-called invisible latent image within the emulsion init the visible black, white and grey radiographic image

27
Q

What is the developer solution?

A

Alkaline solution

28
Q

What factors affect development process?

A

Time and temperature

29
Q

What occurs to films that are overdeveloped?

A

too dark

30
Q

What occurs to films that are under developed?

A

too pale

31
Q

What is the fixer solution

A

Acid solution

32
Q

What is the purpose of the developer solution?

A

reduces sensitised silver halide emulsion to black metallic silver

33
Q

What is the purpose of the fixer solution?

A

Removes the unexposed silver halide emulsion to reveal clear/ white base

34
Q

What occurs to inadequately fixed films?

A

They appear greenish yellow or milky

May become brown with time

35
Q

What are the two types of digital image receptors?

A

Intra-oral and extra-oral solid state receptors

Intra-oral and extra-oral phosphor plate receptors

36
Q

What are the advantages of intra-oral and extra-oral solid state receptors?

A

Produces image quickly
Uses charge coupled device sensors or complementary metal oxide semiconductor sensors
Sensors connected to the computer

37
Q

What are the disadvantages of intra-oral and extra-oral solid state receptors?

A

Intra-oral sensors are bulky and difficult to position in mouth

38
Q

How does the solid state receptor work?

A

Scintiliation layer glows fluorescent when hit by an x-ray
Collision with x-rays creates a voltage which produces an analogue signal
This can be converted to a digital signal with discrete numbers

39
Q

What discrete number appears at a maximum voltage in SSR?

A

0

40
Q

What discrete number appears at a minimum voltage in SSR?

A

255

41
Q

What discrete number is displayed as black?

A

0

42
Q

What discrete number is displayed as white?

A

255

43
Q

What are intra-oral and extra-oral phosphor plate receptors?

A

Different sizes of photo stimulable phosphate storage plates available
Not connected to a computer
Plates easy to use

44
Q

How does the phosphor plates work?

A

X-rays pass through patient and hits phosphor layer in which x-ray energy is stored in plate
Plate passed through the reader in which a laser beam is passed through it which measures energy in plate
This energy is released as green light and a voltage is created which produces an analogue signal converted to a digital signal

45
Q

How many shades of grey does a digital image have?

A

256

46
Q

What is resolution measured in?

A

Line pairs/mm

47
Q

How do the number of line pairs affect the resolution?

A

The more line pairs, the higher the resolution

48
Q

What is the lp/mm for intra-oral direct action?

A

10-20 lp/mm

49
Q

What is the lp/mm of indirect action?

A

5 lp/mm

50
Q

What is the lp/mm

A

7-25 lp/mm

51
Q

How do you increase brightness of an image?

A

increases pixel value

52
Q

How do you increase contrast of image?

A

Makes middle pixel values tend to the lowest/ highest

53
Q

What are the advantages of digital imaging?

A 
Lower elimination dose
Elimination of film processing
Rapid image production
Image manipulation
Easily shown to patient
Electrical storage
54
Q

What are disadvantages of digital imaging?

A

Expensive
Large electronic storage capacity
Sensors may be bulky and easily damaged
Poor quality hard copies

RAD (7 decks)

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