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Radiographical Exposure I - Summer 2024 > Ch. 27 Contrast > Flashcards

Ch. 27 Contrast Flashcards

1
Q
  1. why is contrast a prime component of the photographic properties influencing
    visibility of detail of image quality?
A

Two photographic factors allow detail to be seen:
IR Exposure
Contrast: Difference between adjacent gray shades/image receptor exposures

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2
Q
  1. What are the various terms used to describe contrast/dynmaic range?
A

High contrast - Short scale
Few shades of gray between lightest and darkest
Short/narrow dynamic range

Low contrast - Long scale
More shades of gray between lightest and darkest
Large/wide dynamic range

-In medical imaging, high contrast is not necessarily a good thing.
More shades of gray can reveal more information

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3
Q

2.1 What are the relationship between terms used to describe contrast

A
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4
Q
  1. what is contrast and the factors that affect it?
    kvp
A

-Image contrast refers to the difference between adjacent IR exposure levels
and can be quantified as the percentage or ratio of differences between IR exposures. These differences appear as varying shades from white through gray to black

-Higher kVp produces x-rays with higher energy, which penetrate tissues more uniformly,
resulting in lower contrast. Lower kVp produces x-rays with lower energy, leading to greater
differences in absorption between tissues, resulting in higher contrast.
Explanation: Higher kVp reduces the photoelectric effect and increases Compton scattering,
which both lower image contrast.

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5
Q
  1. what is contrast and the factors that affect it? mAs
A
  • mAs primarily affects the overall density of the image rather than the contrast. However,
    insufficient mAs can lead to underexposed images with high noise, indirectly reducing contrast.
    Explanation: Proper mAs settings ensure adequate exposure, reducing noise and improving the
    visibility of contrast.
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6
Q
  1. what is contrast and the factors that affect it?
A

-Adding filtration (e.g., aluminum filters) to the x-ray beam reduces low-energy x-rays,
which primarily contribute to patient dose and scatter rather than image formation. This can
slightly decrease contrast but improves image quality by reducing scatter.
Explanation: Filtration hardens the x-ray beam, reducing the number of low-energy photons that
contribute to scatter and image degradation.

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7
Q
  1. what is contrast and the factors that affect it? collimation
A

Proper collimation reduces the amount of scattered radiation reaching the detector,
increasing contrast.
Explanation: By limiting the x-ray beam to the area of interest, collimation reduces scatter and
enhances image contrast.

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8
Q
  1. what factors affect image receptor contrast ? 1 of 2
A

Film contrast
Dependent on four factors; Intensifying screen, Film density,
Slope of D log E curve, Processing

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9
Q
  1. what factors affect image receptor contrast ?
    (2 of 2)
A

Digital contrast
-Histogram and LUT used affect final image
-Window width (WW) settings determine final contrast look

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10
Q
  1. what are factors that that affefct subject contrast?
    Dependent on: (1 of 4)
A

Kilovoltage
-Wider range of photon energy
Greater penetrability
Greater range of exposures
Greater amount of scatter
Longer scale of contrast (film

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11
Q
  1. what are factors that that affefct subject contrast?
    Dependent on: (2of4)
A

Amount of irradiated material
-Type of irradiated material

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12
Q
  1. what are factors that that affefct subject contrast?
    Dependent on: (3 of 4)
A

Dependent on thickness of part and field size

Increase in thickness and field size
Increase scatter
Longer scale of contrast (film)
(When difference between adjacent thickness of the body is great, subject contrast increases)

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13
Q
  1. what are factors that that affefct subject contrast?
    Dependent on: (4 of 4)
A

Type of Irradiated Material
-arge difference in atomic number and tissue density of adjacent tissues, subject contrast is increased

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14
Q
  1. what technical factors changes is necessary to achieve optimal contrast?
    kvp
A

-kvp: Increased kVp and decreased contrast

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15
Q
  1. what technical factors changes is necessary to achieve optimal contrast?
    mAs
A

no answer lol

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16
Q
  1. what technical factors changes is necessary to achieve optimal contrast?
    -focal spot size
A

: not detected

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17
Q
  1. what technical factors changes is necessary to achieve optimal contrast?
    anode heel effect
A

-anode heel effect: little effect on contrast

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18
Q
  1. what technical factors changes is necessary to achieve optimal contrast?
    beam restriction
A

-beam restriction: Direct effect; Reduces scatter and increases contrast

19
Q
  1. what technical factors changes is necessary to achieve optimal contrast?
    -anatomical part
A

-anatomical part:Dependent on tissue type, thickness,

20
Q
  1. what technical factors changes is necessary to achieve optimal contrast?
    SID:
A

no answer yet

21
Q
  1. what technical factors changes is necessary to achieve optimal contrast?
    OID
A

OID: Air gap technique; Increases contrast

22
Q
  1. what technical factors changes is necessary to achieve optimal contrast?
    filtration
A

Increased filtration >Increased average beam energy>Decreased
contrast (film)

-Filtration does not greatly impact contrast with digital systems
23
Q
  1. what technical factors changes is necessary to achieve optimal contrast?
    grids
A

-grids: Increase grid ratio, increase contrast; Contrast improvement factor (K);
Most grids provide K factor between 1.5 and 3.5; Higher grid ratios yield higher K factor

24
Q
  1. What are recommended adjustments to improve contrast under various conditions?
    Technical Setting
A

-lower kilovolt peak (kVp) settings to enhance contrast
-Adjust milliampere-seconds (mAs) to ensure adequate exposure

25
Q
  1. What are recommended adjustments to improve contrast under various conditions? Scatter Radiation Control
A

Employ grids to reduce scatter radiation
-Air Gap Technique: Increase OID

26
Q
  1. What are recommended adjustments to improve contrast under various conditions? Image Receptor and Processing
A

-Digital Image Processing: : Utilize post-processing algorithms such as windowing, leveling, and contrast enhancement

27
Q
  1. What are recommended adjustments to improve contrast under various conditions? Proper Film Processing:
A
  • correct development time, temperature, and chemical
    concentration
28
Q
  1. What are recommended adjustments to improve contrast under various conditions? Patient and Subject Factors
A

-proper Positioning

29
Q
  1. What are recommended adjustments to improve contrast under various conditions?
    Contrast Agents:
A

Use contrast media when necessary to enhance the visibility of specific
structures or tissues.

30
Q
  1. What are recommended adjustments to improve contrast under various conditions?
    Contrast Agents:
A

Use contrast media when necessary to enhance the visibility of specific
structures or tissues.

31
Q
  1. What are recommended adjustments to improve contrast under various conditions?
    Viewing Conditions
A

-Monitor Quality
-Ambient Lighting

32
Q
  1. How does each influencing factor affects contrasts? kvp
A

1.kVp (Kilovolt Peak)
Effect: Lower kVp increases image contrast by enhancing differential absorption between
tissues. Higher kVp decreases contrast due to increased penetration and Compton scatter.

33
Q
  1. How does each influencing factor affects contrasts? mAs (Milliampere-Seconds)
A

Effect: Primarily affects image density. Adequate mAs ensures optimal exposure, reducing noise
and indirectly maintaining contrast.

34
Q
  1. How does each influencing factor affects contrasts? Grids
A

Effect: Grids reduce scatter radiation, which improves image contrast by preventing scatter from
reaching the image receptor.

35
Q
  1. How does each influencing factor affects contrasts? Air Gap Technique
A

Effect: Increasing the distance between the patient and the image receptor reduces scatter,
enhancing contrast.reaching the image receptor.

36
Q
  1. How does each influencing factor affects contrasts? Digital Image Processing
A

Effect: Post-processing techniques like windowing and leveling can adjust and optimize contrast
in digital images

37
Q
  1. How does each influencing factor affects contrasts? 6. Film Processing (For Film Radiography)
A

Effect: Proper development time, temperature, and chemical concentration ensure optimal
contrast. Deviations can result in either increased fog (decreased contrast) or underdevelopment
(reduced contrast).

38
Q
  1. How does each influencing factor affects contrasts? 7.Subject Contrast
A

Effect: Differences in tissue density, thickness, and atomic number naturally affect contrast.
Higher inherent differences improve image contrast.

39
Q
  1. How does each influencing factor affects contrasts? Contrast Agents
A

Effect: Introducing contrast media (e.g., barium, iodine) enhances the contrast of specific
structures by altering their x-ray absorption characteristics.

40
Q
  1. How does each influencing factor affects contrasts? . Film Processing (For Film Radiography)
A

Effect: Proper development time, temperature, and chemical concentration ensure optimal
contrast. Deviations can result in either increased fog (decreased contrast) or underdevelopment
(reduced contrast).

41
Q
  1. How does each influencing factor affects contrasts? Subject Contrast
A

Effect: Differences in tissue density, thickness, and atomic number naturally affect contrast.
Higher inherent differences improve image contrast.

42
Q
  1. How does each influencing factor affects contrasts? Monitor Quality and Viewing Conditions
A

Effect: High-quality, calibrated monitors and proper ambient lighting conditions improve the
perceived contrast, ensuring accurate image interpretation.

43
Q

Does this increase or decrease contrast ? Fill in blanks .

A

Radiographical Exposure I - Summer 2024 (6 decks)

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