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w.RADT 161 > week 8: image quality > Flashcards

week 8: image quality Flashcards

1
Q

What does a quality image accurately represent?

A

(1) accurately represents the anatomic area of interest and (2) information is well visualized for diagnosis

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2
Q

What two factors (2 types of resolution) determine the overall quality of the radiographic image?

A

contrast resolution, spatial resolution

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3
Q

visibility of detail

A

contrast resolution

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4
Q

sharpness of detail

A

spatial resolution

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5
Q

image density (optical density or OD): the ____________ represent the ___________ properties of the anatomic part imaged

A

varying optical densities, attenuation

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6
Q

amount of luminance (light emission) of a display monitor

A

image brightness

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7
Q

____________ are geometric qualities

A

Detail and distortion

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8
Q

___________ are photographic qualities

A

optical density and contrast

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9
Q

spatial resolution is used to evaluate the accuracy of the _____________________

A

anatomic structural lines displayed

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10
Q

high contrast images display _________________ but ____________

A

fewer shades of gray but greater differences among them

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11
Q

low contrast images display ________________ but _____________

A

greater number of gray shades but smaller differences among them

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12
Q

clear area of the image = ___ optical density

A

low

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13
Q

black area of the image = ____ optical density

A

high

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14
Q

with digital images, ________ is now the name for optical density

A

brightness

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15
Q

what is another definition for film densities (Bontrager)?

A

defined as the amount of “blackness” on the processed radiograph

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16
Q

clear area of the image = ________ brightness

A

increased

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17
Q

black area of the image = ________ brightness

A

decreased

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18
Q

optical density and brightness result from the ________ of radiation reaching a particular area

A

quantity

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19
Q

What is the primary technical factor that controls the amount of OD in an analog image (film/screen image)?

A

mAs; controls the quantity the reaches the film AND how the manifest image looks

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20
Q

What is the primary factor that controls the amount of OD in a digital image?

A

mAs; controls quantity that reaches the IR however the computer algorithms control how the manifest images look

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21
Q

true/false: mAs only controls the quantity of photons that reaches the IR/film in analog

A

false, it controls in both analog and digital systems

22
Q

in a digital image _______ controls the brightness of the manifest image

A

computer algorithms

23
Q

in an analog image __________ controls optical density of the manifest image

A

mAs

24
Q

with respect to mAs, kVp, and optical densities/brightness, ______ “controls” and ____ “influences” quantity of photons

A

mAs, kVp

25
Q

in an image, low density is _________

A

increased brightness

26
Q

in an image, high density is __________

A

decreased brightness

27
Q

Radiographic density and tissue density are ___________ to each other

A

inversely related

28
Q

increased tissue density will make that particular area on an image _________

A

brighter/lighter

29
Q

increased radiographic density will make that particular area on an image ___________-

A

darker

30
Q

quantum mottle is due to ___________________; ______ photons and results in _________

A

insufficient mAs for anatomy of interest, too few, grainy appearance

31
Q

number of different shades of gray that can be displayed

A

gray scale

32
Q

range of shades of gray

A

scale of contrast

33
Q

Low scale of contrast, long gray scale = _____________________

A

many shades of gray, small differences

34
Q

High scale of contrast, short gray scale = ______________________________

A

not very many shades of gray; dramatic difference between high and low brightness/densities

35
Q

What is the primary technical factor that controls the scale of contrast in an analog image (film/screen image)?

A

kVp

36
Q

high kVp = ____ scale
low kVp = ____ scale

A

long, short

37
Q

What is the primary factor that controls the scale of contrast in a digital image?

A

kVp

38
Q

What is the difference between radiographic contrast and subject contrast?

A
  1. radiographic contrast = photographic property
  2. subject contrast = result of the absorption characteristics of the anatomic tissue and the quality of the x-ray beam
39
Q

what is contrast resolution?

A

ability to distinguish between objects similar in subject contrast

40
Q

How should mAs be set to reduce patient exposure?

A

high mA station, low seconds (reciprocity law)

41
Q

what is the purpose of filtration of the beam?

A

remove low energy x-ray photons that have no diagnostic value

42
Q

what are 2 types of filtration?

A

inherent, added

43
Q

what is the type of added filtration?

A

aluminum

44
Q

tube filtration (can/can not) be changed

A

can not

45
Q

tube filtration is based on _____________

A

federal regulation standards

46
Q

increased SID = (more/less) intense beam

A

less

47
Q

inverse square law: intensity of the x-ray beam is ___________________ from the source

A

inversely proportional to the square of the distance

48
Q

direct law: The mAs/distance compensation formula provides a mathematical calculation for adjusting the ____ when changing the ______.

A

mAs, SID

49
Q

increasing or decreasing the kVp by 15% has the same effect as __________________

A

doubling or halving the mAs

50
Q

what technical factor is responsible for patient radiation dose?

A

mAs

51
Q

what equation interferes with intensity and distance?

A

inverse square law

w.RADT 161 (10 decks)

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