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C2 > IMAGE QUALITY > Flashcards

IMAGE QUALITY Flashcards

1
Q

What improves spatial resolution?

A

Spatial resolution improves as screen blur, motion blur, and geometric blur decrease.

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2
Q

It is the exactness of representation of the patient’s anatomy on an image.

A

image quality

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3
Q

Name the three major categories of radiographic quality.

A

Film Factors, Geometric Factors, and Subject Factors

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4
Q

A radiograph that faithfully reproduces structures and tissues with good spatial resolution, contrast resolution, low noise, and minimal artifacts.

A

high quality radiograph

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5
Q

The ability to image small objects with high subject contrast, such as bone-soft tissue interfaces.

A

spatial resolution

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6
Q

What does contrast resolution measure?

A

The ability to distinguish anatomical structures of similar subject contrast, such as liver-spleen differentiation.

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7
Q

Define detail in radiographic terms.

A

Detail refers to the degree of sharpness of structural lines on a radiograph.

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8
Q

What is visibility of detail?

A

The ability to visualize recorded detail when image contrast and optical density are optimized.

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9
Q

The random fluctuation in the optical density (OD) of the image, often appearing as graininess.

A

radiographic noise

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10
Q

What are the components of radiographic noise?

A

Film graininess, structure mottle, quantum mottle, and scatter radiation.

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11
Q

The distribution in size and space of silver halide grains in the emulsion, contributing minimally to radiographic noise.

A

film graininess

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12
Q

The principal contributor to radiographic noise, caused by the random nature of x-ray interactions with the image receptor.

A

quantum mottle

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13
Q

How can quantum mottle be reduced?

A

By using high-mAs, low-kVp settings, and slower image receptors.

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14
Q

refers to the sensitivity of x-rays to film, which influences both resolution and noise.

A

speed

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15
Q

What factors influence radiographic quality?

A

Film Factors, Geometric Factors, and Subject Factors.

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16
Q

To study the relationship between film exposure intensity and resulting blackness after processing.

A

sensitometry

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17
Q

What does the characteristic curve represent?

A

The relationship between optical density (OD) and radiation exposure.

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18
Q

Name the sections of the characteristic curve.

A

Toe, shoulder, and straight-line portions.

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19
Q

What tool is used to create a characteristic curve?

A

A sensitometer (optical step wedge) and a densitometer.

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20
Q

a logarithmic function representing the darkness of a radiograph.

A

optical density

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21
Q

What is base density?

A

The optical density inherent in the film base, generally around 0.1.

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22
Q

What causes fog density?

A

Caused by inadvertent exposure during storage, chemical contamination, or improper processing.

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23
Q

Describe reciprocity law.

A

States that OD on a radiograph is proportional only to the total energy imparted to the film.

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24
Q

How does film contrast relate to the characteristic curve?

A

Film contrast is related to the slope of the straight-line portion of the characteristic curve.

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25
Q

product of image receptor contrast and subject contrast.

A

radiographic contrast

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26
Q

What factors influence image receptor contrast?

A

The range of ODs and film processing technique.

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27
Q

Determined by the size, shape, and x-ray attenuating characteristics of the anatomy, as well as the kVp of the x-ray beam.

A

subject contrast

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28
Q

Define speed in terms of image receptor sensitivity.

A

Speed = 1 / Exposure in roentgens needed to produce an OD of 1.0 above base and fog.

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29
Q

The range of exposure over which the image receptor responds with ODs in the diagnostically useful range.

A

latitude

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30
Q

How does development time and temperature affect radiographic contrast?

A

Increased time and temperature increase speed and fog, which can decrease image receptor contrast.

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31
Q

Name the three principal geometric factors affecting radiographic quality.

A

Magnification, Distortion, and Focal-spot Blur.

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32
Q

What is magnification in radiography?

A

Condition where the image on the radiograph is larger than the object it represents.

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33
Q

How can magnification be minimized?

A

By using a large SID and a small OID.

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34
Q

Define magnification factor.

A

MF = SID / SOD (Source-to-Image Distance divided by Source-to-Object Distance).

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35
Q

Unequal magnification of different parts of an object, often due to shape, position, or thickness.

A

distortion

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36
Q

How does object thickness affect distortion?

A

Thicker objects result in greater distortion due to unequal magnification.

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37
Q

occurs when an object is inclined and not parallel to the image receptor.

A

foreshortening

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38
Q

Caused by an inclined object that is not located on the central x-ray beam.

A

elongation

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39
Q

Misrepresentation of spatial relationships among objects due to different distances from the image receptor.

A

spatial distortion

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40
Q

A blurred region on the radiograph, influenced by the effective size of the focal spot.

A

focal-spot blur

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41
Q

Where is focal-spot blur smaller on the radiograph?

A

Smaller on the anode side and larger on the cathode side.

42
Q

What factors reduce focal-spot blur?

A

Use of a small focal spot size and a small OID.

43
Q

The phenomenon where the image toward the cathode side has higher blur and poorer resolution than the anode side.

A

heel effect

44
Q

List the main subject factors in radiographic quality.

A

Subject contrast, patient thickness, tissue mass density, effective atomic number, object shape, and kilovolt peak.

45
Q

How does patient thickness affect subject contrast?

A

Thicker body sections attenuate more x-rays, impacting the contrast between sections.

46
Q

A factor affecting subject contrast; denser tissues attenuate more x-rays.

A

tissue mass density

47
Q

How do photoelectric interactions vary with atomic number?

A

They vary in proportion to the cube of the atomic number (Z³), affecting subject contrast.

48
Q

A reduction in spatial and contrast resolution due to characteristics of the subject.

A

absorption blue

49
Q

How does kVp influence subject contrast?

A

Lower kVp results in higher subject contrast with a short gray scale, while higher kVp results in lower contrast with a long gray scale.

50
Q

Name two disadvantages of low-kVp technique.

A

Higher patient dose and less penetration of the x-ray beam.

51
Q

Blurring caused by patient or x-ray tube movement during exposure.

A

motion blur

52
Q

How is voluntary motion controlled in radiography?

A

By immobilization or instructing the patient to remain still.

53
Q

How is involuntary motion controlled?

A

By using a short exposure time.

54
Q

What factors help reduce motion blur?

A

Short exposure time, large SID, small OID, and patient instructions or restraints.

55
Q

List tools that improve radiographic quality

A

Proper patient positioning, selecting the right imaging devices, and using proper technique.

56
Q

How should a structure be positioned in relation to the IR?

A

As close to the IR as possible and parallel to the plane of the IR.

57
Q

What is the role of a central ray in radiographic quality?

A

The central ray should be incident on the center of the structure to ensure accurate imaging.

58
Q

Why is patient immobilization important?

A

To minimize motion blur during imaging.

59
Q

How do intensifying screens affect patient dose?

A

They reduce patient dose by a factor of approximately 20.

60
Q

What are the effects of increased image receptor speed?

A

Increases radiographic noise and decreases spatial resolution.

61
Q

How does low contrast imaging affect radiographic latitude?

A

provides a wider latitude or margin of error in exposure factors.

62
Q

What is the primary control of radiographic contrast?

A

Kilovoltage peak (kVp).

63
Q

What happens to subject contrast as kVp increases?

A

Subject contrast decreases due to increased Compton interactions and reduced differential absorption.

64
Q

What is the principal advantage of using high kVp?

A

Reduced patient dose and wider exposure latitude.

65
Q

What is the principal disadvantage of high kVp?

A

Loss of contrast in the radiographic image.

66
Q

Define milliampere-second (mAs) in radiography.

A

mAs is the primary control of optical density (OD) in a radiograph.

67
Q

What effect does increasing mAs have on patient dose?

A

It increases patient dose by raising the radiation quantity.

68
Q

How does filtration affect the x-ray beam?

A

Filtration reduces beam intensity and enhances beam quality.

69
Q

Filtration reduces beam intensity and enhances beam quality.

A

Increased SID decreases optical density but does not change contrast.

70
Q

Name factors that increase patient dose.

A

Increased film speed, screen speed, grid ratio, patient thickness, and field size.

71
Q

What effect does grid ratio have on contrast?

A

Higher grid ratios improve contrast by reducing scatter radiation.

72
Q

What factors affect film contrast?

A

Processing time, temperature, patient thickness, and field size.

73
Q

What is the impact of field size on contrast?

A

Larger field sizes decrease contrast by increasing scatter radiation.

74
Q

Substances used to enhance contrast of specific body areas, commonly affecting image contrast positively.

A

contrast media

75
Q

How does focal-spot size affect radiographic image quality?

A

Larger focal-spot size increases focal-spot blur, reducing image sharpness.

76
Q

What happens when SID is increased?

A

Magnification decreases, spatial resolution improves, and patient dose reduces.

77
Q

Define OID in radiography.

A

Object-to-Image Distance - the distance between the object being imaged and the image receptor.

78
Q

How does increasing OID affect the radiographic image?

A

Increased OID leads to more magnification, greater focal-spot blur, and reduced spatial resolution.

79
Q

Describe screen-film contact.

A

The closeness between the intensifying screen and the film, which affects image sharpness.

80
Q

How does mAs influence noise in radiography?

A

Higher mAs reduces radiographic noise, while too low mAs increases it.

81
Q

What is the purpose of voltage ripple in x-ray imaging?

A

Reduces the amount of radiation fluctuation, affecting contrast and noise.

82
Q

How does increased filtration affect contrast?

A

It generally reduces contrast by removing low-energy x-rays that contribute to image contrast.

83
Q

What is film speed?

A

The sensitivity of film to x-ray exposure, influencing both contrast and optical density.

84
Q

The speed at which the intensifying screen responds to x-ray exposure.

A

screen speed

85
Q

How does development temperature influence radiographic contrast?

A

Higher temperature increases fog, which can decrease contrast.

86
Q

Describe the toe region of the characteristic curve.

A

The low-exposure area where large changes in exposure result in only small changes in optical density.

87
Q

What does the shoulder region of the characteristic curve represent?

A

High exposure where large exposure changes result in minimal optical density changes.

88
Q

An instrument that exposes film to known light levels to measure film sensitivity and contrast.

A

sensitometer

89
Q

Measures the optical density of exposed film by assessing light transmission through the film.

A

densitometer

90
Q

What is the average gradient of a film?

A

A measure of the slope of the characteristic curve, representing image receptor contrast.

91
Q

Define average gradient in terms of optical density and exposure.

A

Average Gradient = (OD2 - OD1) / (LRE2 - LRE1) over the useful range of optical density.

92
Q

How does latitude relate to contrast?

A

Latitude and contrast are inversely proportional; wider latitude corresponds to lower contrast.

93
Q

Latitude and contrast are inversely proportional; wider latitude corresponds to lower contrast.

A

Contrast inherent to the screen-film combination, influenced by film processing and optical density range.

94
Q

What is subject contrast influenced by?

A

Anatomy size and shape, atomic number of tissues, and energy of the x-ray beam.

95
Q

Explain the impact of low ripple power on radiographic image quality.

A

Reduces the likelihood of motion blur and improves image stability.

96
Q

What happens to OD with increased mAs?

A

Optical Density (OD) increases with higher mAs.

97
Q

How does screen-film contact affect image detail?

A

Poor screen-film contact leads to loss of detail and image blurring.

98
Q

An alternative to the sensitometer, used for evaluating image contrast by measuring exposure levels.

A

penetrometer

99
Q

Define high-speed IR in terms of sensitivity.

A

image receptors with speed ratings over 100, used for fast imaging but with more noise.

100
Q

Why is optical density important in radiography?

A

Determines the visual quality of the image, with optimal range enhancing detail and contrast.

C2 (7 decks)

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