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RT L1 > 4: RT Imaging > Flashcards

4: RT Imaging Flashcards

1
Q

What is the phenomena in which grains of silver clump together?

A

Graininess

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2
Q

The emulsion or image layer of the unexposed film contains grains of what?

A

Silver bromide

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3
Q

A graph showing the relationship between the material thickness, kilo voltage and time is called what?

A

An exposure chart

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4
Q

Film selection for an X-ray exposure depends on what? (3)

A
  1. Thickness of part
  2. Material of specimen
  3. Voltage range of X-ray machine
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5
Q

A high speed film is one which…

A

Needs low exposure for a given density

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6
Q

The sharpness of a radiographic image’s outline (the abruptness of density transition) is termed radiographic what?

A

Definition

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7
Q

Radiographic contrast is the…

A

Sum if the film and subject contrast

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8
Q

In general grain size in a slow speed film is _________ a fast film.

A

Smaller than

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9
Q

When comparing the speeds of 2 films using their characteristic curves (density vs log relative exposure) the faster film curve will lie _______ the slower film.

A

Left of

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10
Q

The slope of a characteristic curve for an industrial X-ray film indicates what?

A

Contrast

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11
Q

The metallic silver formed when an X-ray film is exposed but not developed is called what?

A

The latent image

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12
Q

In radiographic film, imaging the suspension of silver halide crystals in a gelatinous binding agent is called a what?

A

Emulsion

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13
Q

What is inherent unsharpness a direct result of?

A

Secondary electrons generated in film emulsion making silver halide grains viewable

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14
Q

How are grains, speed and sharpness related?

A

Larger grains = faster speed = more unsharpness

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15
Q

The higher the film…

A

The larger the grains and the less exposure time is required

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16
Q

What is the most common and uncommon film types?

A

Class l is most common until thicker components, fine grains

Class lll most uncommon, mostly concrete shots (material 3+” thick), coarse grains

17
Q

A characteristic curve determines what?

A

FILM CONTRAST

18
Q

What is latitude?

A

Ability of film to cover range of thicknesses for a given exposure (dependant on films contrast level and relative speed)

19
Q

What does a characteristic curve show?

A

How film responds to different amounts of exposure

20
Q

Exposure charts are plotted against what?

A

Thickness

21
Q

What are 2 ways to prepare an exposure chart?

A
  1. With a densitometer (how we did in class)

2. With a characteristic curve

22
Q

For density of 2, how much light is being transmitted through?

A

One

23
Q

What is subject contrast?

A

Ratio of intensities passing through 2 material thicknesses

24
Q

What are 3 characteristics of a good film base?

A
  1. Water/chemical resistant
  2. Non-combustible
  3. Dimensionally designed for easy drying
25
Q

What happens to the crystals/grains of a film when exposed?

A

Exposure to radiation causes a change in physical structure

26
Q

Once development starts, a reaction occurs causing exposed silver grains to convert to what?

A

Black metallic silver

27
Q

What are single coated films often used for?

A

Critical inspections where super fine detail is required

28
Q

What is the substrate/subbing layer and what is its purpose?

A

Layer between actual film base and the emulsion.

Sole purpose to hold emulsion to film base.

29
Q

What is the super coat/outside layer for?

A

Scratch and pressure resistance gelatin protection to emulsion

30
Q

Why would blue dye be added to film base?

A

To improve viewing of undeveloped images

31
Q

The higher the film class..

A

Somewhat lesser the image quality

32
Q

In general, the faster the speed = lower the ________ = _________ of latitude

A

Faster the speed = lower the contrast = wider range of latitude

33
Q

What are 2 other names for a characteristic curve?

A
  1. H & D Curve

2. Sensitometric Curve

34
Q

What is plotted against what in a characteristic curve?

A

Densities plotted against logarithms of relative exposures

35
Q

Exposure charts show the relationship between what?

A

Material thickness, energy (kV) and exposure (mAm)

36
Q

What is the difference between a gamma and an X-ray exposure chart?

A

For gamma there’s no variable factor that corresponds to kilo voltage.

RT L1 (10 decks)

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