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Radiologic Technology > Exam 2 > Flashcards

Exam 2 Flashcards

0
Q

what is screening mammo?

A

for asymptomatic women (50+ yrs); min of 2 views

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1
Q

what are the 3types of mammo?

A

screening, diagnostic, & baseline

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2
Q

what is diagnostic mammo?

A

for pt’s w symptoms or elevated risk factors; 2-3 views

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3
Q

what is baseline mammo?

A

very FIRST XR of breasts (usually before 40 yrs); used as comparison w ALL FUTURE MAMMOS

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4
Q

80% of breast cancers are?

A

ductal (mammory duct)

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5
Q

what are the 3 target filter combo’s used in mammo?

A

Mo/Mo, Mo/Rh, Rh/Rh (Mo = molybdenum, Rh = Rhodium)

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6
Q

Mo targets produce char. XRs w an energy of?

A

19 keV (good for XRs of smaller breasts)

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7
Q

Rh targets produce char. XRs w an energy of?

A

23 keV (more penetration for thicker breasts)

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8
Q

what is the best target filter combo for thin breasts?

A

Mo/Mo

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9
Q

what is the best target filter combo for pt’s w thick breasts?

A

Rh/Rh

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10
Q

what is the effect of focal spot on spatial res?

A

(inverse) smaller focal spot –> higher spatial res

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11
Q

what is the purpose of angling the anode and tilting the tube in XR, in mammo?

A

to obtain smaller focal spot size of 0.3/0.1

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12
Q

how does mammo obtain a focal spot size of 0.3/0.1?

A

angling anode 23º and tilting tube 6º

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13
Q

what is the anode angle in mammo?

A

23º

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14
Q

how much is the XR tube tilted in mammo?

A

6º

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15
Q

what are the advantages of the anode angle and tube tilt in mammo?

A

smaller effective focal spot –> higher spatial res; CR becomes II to chest wall & no tissue is missed

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16
Q

what is the inherent filtration used in mammo?

A

0.1 mm of Al equivalent

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17
Q

what is the total filtration used in mammo?

A

no less than 0.5 mm of Al equivalent

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18
Q

thick dense breasts requires what target filter combo?

A

Rh/Rh

Mo/Mo for thin fatty breasts

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19
Q

in mammo, to get uniform density, where should you position the anode? the cathode?

A

anode over nipple

cathode over chest wall

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20
Q

advantages of compression in mammo? (10)

A

more uniform thickness/OD,
reduce scatter rad,
reduce pt motion,
increase spatial/contrast res,
tissue near chest wall less likely to underexposed,
tissue near nipples less likely to be overexposed,
brings tissue closer to IR –> less focal spot blur,
less pt dose,
less superimposition of tissue (bc spreads it out),
reduces absorption blur

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21
Q

what is the appropriate grid frequency in mammo?

A

30-50 lines/cm

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22
Q

what is the appropriate grid ratio used in mammo?

A

4:1 to 5:1 focused grid

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23
Q

in mammo, what happens w use of 4:1 grid?

A

nearly doubles pt dose, but significantly improves contrast

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24
Q

what is the unique grid specific for mammo?

A

high transmission cellular grid (HTC)

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25
Q

what is the purpose of an HTC grid?

A

reduces scatter in TWO directions,

has clean-up char.’s of crossed grid

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26
Q

what is the grid ratio of an HTC grid?

A

3:8:1

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27
Q

where is the AEC located in a mammo unit?

A

under the IR (to min. OID & improve spatial res)

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28
Q

in mammo, the effective focal spot should not exceed?

A

0.1 mm (to help investigate small lesions/micro-calcifications)

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29
Q

how do you place a single emulsion mammo film inside a cassette?

A

XR film places btw XR tube and rad IS; w emulsion ALWAYS facing IS

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30
Q

what material makes up the CCD in mammo?

A

a-Si (indirect) or a-Se (direct)

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31
Q

CCD used in mammo converts ______ to _______

A

vis. light photons to e-‘s

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32
Q

electronic noise in digital mammo can be reduced by?

A

cooling the detector (which improves contrast res.)

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33
Q

members of a mammo QC team?

A

radiologist (ultimate responsibility), medical physicist, and mammographer (most hands on)

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34
Q

diff btw QC & QA?

A

QC - eval./maintain equip., QA - eval. ppl

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35
Q

role of a med physicist in mammo QC?

A

principally does annual performance eval. of imaging systems/equip.

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36
Q

role of a radiologist in mammo QC?

A

has ultimate responsibility, supervises entire QA program, oversees/selects team, supervises pt comm. & tracking

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37
Q

4 factors that affect blurring of unwanted structures in tomo?

A

D of object from focal plane
exposure angle
OID
tube trajectory

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38
Q

how does exposure angle in tomo affect blurring of unwanted structures?

A

increase exposure angle –> increase blurring

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39
Q

how does OID in tomo affect blurring of unwanted structures?

A

increase OID –> increase blurring

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40
Q

how does tube trajectory in tomo affect blurring of unwanted structures?

A

linear trajectory has least blurring, whereas spiral/hypocycloidal has the most blurring

41
Q

what is the relationship btw tomo angle & slice thickness

A

inverse (larger angle gives thinner slices)

42
Q

what is the focal plane in tomo?

A

(aka objective plane) plane in which object is clear & in focus; where the img is the most sharp

43
Q

what is zonography?

A

uses tomo angle LESS than 10º to get very large section thickness

44
Q

when is zonography used?

A

when subject contrast is so low that thin section tomo will not give clear img

45
Q

what are most common exams performed for zonography?

A

chest and renal

46
Q

what are the advantages of tomo?

A

(principally) to improve rad. contrast, & to blur overlying/underlying tissue structures

47
Q

what is the disadvantage of tomo?

A

increased pt dose

48
Q

what is the rad dose of a single tomo exposure of the kidneys?

A

1000 mrad

49
Q

what is panoramic tomo?

A

XR tube & IR move around the head to img curved bony structures (mandible)

50
Q

what is the most common use for panoramic tomo?

A

dental survey

51
Q

2 formulas for magnification factor?

A 
MF = img size/object size
MF = SID/SOD
52
Q

2 daily tasks in mammo QC

A

darkroom cleanliness, processor QC

53
Q

3 weekly tasks in mammo QC

A

viewboxes/viewing conditions, phantom imgs, & screen cleanliness (screens should be allowed to air dry VERTICALLY)

54
Q

3 semiannual tasks in mammo QC

A

darkroom fog, screen-film contact, compression

55
Q

how much luminance is required for mammo viewboxes?

A

3000 nit (candela per square meter)

56
Q

when should phantom img’s be taken?

A

after equipment installation/maintenance

57
Q

how often should a repeat analysis be performed?

A

quarterly

58
Q

what is an acceptable repeat rate?

A

2%

59
Q

what is the min. mammo’s to be included during a repeat anal.?

A

at least 250 mammo’s

60
Q

what is the formula to determine the repeat rate?

A

repeat rate (%) = (# of repeated XRs/total # of XRs) x 100

61
Q

how is screen film-contact checked?

A

perform wire mesh test and view it from a distance of 3 ft. dark areas indicate poor screen-film contact

62
Q

how often should you perform a wire mesh test

A

semiannually

63
Q

how much compression is required in mammo?

A

25-40 lbs held for at least 15 seconds

64
Q

in tomo, what is the net effect of increased blurring?

A

a thinner focal plane

65
Q

what is fulcrum?

A

a pivot point along the connecting rod btw XR tube & film in a tomographic system; only anatomic structures in this plane are seen clearly (area of interest)

66
Q

fulcrum types?

A

adjustable & fixed

67
Q

what is trajectory (tomo)?

A

type of movement (5 types)

68
Q

what are the 5 trajectories in tomo?

A

linear (least blurring), elliptical, circular, spiral, & hypocycloidal (most blurring)

69
Q

DICOM?

A

digital imaging & communications in medicine

70
Q

SMPTE stands for?

A

society of motion pictures & television engineers

71
Q

what is an SMPTE pattern?

A

measures the res. of a display system, to point out any gross deviations in luminance adjustment (5% on black, 95% on white)

72
Q

GSDF?

A

“gray scale display f(x)”, ensures consistent gray scale appearance in img transfers

73
Q

DIN?

A

(Deutaches Instiitut fur Normung) acceptance testing standard to address requirements for digital display

74
Q

AAPM TG 18?

A

(American Assoc. of Physicists in Medicine, developed test patterns/procedures in Task Group Report 18)

75
Q

what does a photometer do?

A

measures the amount of light

76
Q

2 types of photometers?

A

near range & telescopic (1m away from monitor)

77
Q

in regards to photometers, the National Institute of Standards & Technology (NIST) recommends…..?

A

better than 5% response at 50º angulations

78
Q

2 types of geometric distortions?

A

pincushion & barrel-like distortions

79
Q

geometric distortions affect what?

A

relative size/shape of image features

80
Q

what are the 2 types of reflection?

A

diffuse & specular

81
Q

what is diffusion reflection

A

seen at all points

82
Q

what is specular reflection

A

a reflection only seen at one vantage point

83
Q

what is used to evaluate display res?

A

TG 18 CX & TG 18 QC

84
Q

what is used to eval. res. uniformity?

A

TG 18 PX

85
Q

what is used to eval. display noise on a digital system?

A

TG 18 AFC pattern

86
Q

the max non-uniformity of a display device should be

A

LESS THAN 30%

87
Q

in mammo, low kVp produces ____ _________ & ____ ________, which gives better contrast

A

less Compton Scatter & more photoelectric absorption

88
Q

how many lp’s in mammo? what is the result?

A

15 lp’s for better spatial res. (v. digi’s 10 lp’s)

89
Q

how many total lobes in the breast?

A

30-40

90
Q

(tomo) more movement/trajectory produces what?

A

a sharper image

92
Q

VESA

A

video electronic standard assoc

93
Q

does acceptance testing for the requirements for digi. display systems

A

DIN

94
Q

ea breast is made up of how many lobes

A

15-20

95
Q

do we use magnification in mammo?

A

not routinely (doubles dose)

96
Q

what is the dose density relationship displayed in digi rad?

A

response of a CCD is linear, not curvilinear like screen film

97
Q

Ex. pt’s femur is XRed w grid ratio of 8:1 at an SID of 40”. The femur was 4” away from the IR. what is the actual size of the femur if the img size was 24 cm?

A

21.62 cm

98
Q

In digital mammo, the repeat rate should not exceed?

A

1%

99
Q

how many women get breast cancer?

A

1/8

100
Q

in digi mammo, spatial res. is _________ bc of XR tube focal spot size

A

superior

101
Q

what is spatial res. limited by in digi mammo?

A

pixel size

Radiologic Technology (5 decks)

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