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Radiologic Technology > Final > Flashcards

Final Flashcards

1
Q

QC limit of kVp calibration

A

measured kVp should be w/in 10% of indicated kVp

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2
Q

Breast cancer

A

about 80% occurs in ductal tissue (1/8 women)

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2
Q

ability to detect differences in brightness levels

A

contrast perception

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3
Q

how does moire artifact appear on XR?

A

appears as diagonal lines all across the img

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4
Q

should complete a visual checklist on a monthly basis

A

mammographer

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5
Q

how to reduce quantum mottle?

A

+ mAs

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5
Q

What is a moire artifact, what causes it?

A

when grid lines & scanning lasers are II; or during frequency harmonics/matching (when grid frequency gets close to laser scanning frequency)

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6
Q

advantages of slip ring?

A

contin. rotation of XR tube; transfers electrical power, scanning; instructions, & detected signals btw stationary components & rotating gantry components; eliminate need to stop rotation of gantry after ea. scan (no cables); led to development of helical/spiral (volume) scanning

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6
Q

How much total filtration is used in radiographic machines?

A

min. of 2.5 mm AL

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7
Q

used for evaluating diffuse reflection (light randomly scattered on the digi. display monitor); tested under ambient condition or total darkness; anti-reflective coating can min. reflections

A

TG 18 AD

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7
Q

mammograms are taken w _________ cassettes

A

single screen

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7
Q

most mammographic systems now have a moving grid w a ratio of

A

5:1

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7
Q

In DF, spatial res. is determined by:

A

img matrix & size of I.I.

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8
Q

controls img brightness determines the CT # that will be the center of the WW

A

window level (WL)

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8
Q

most QC testing on equipment done

A

annually

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9
Q

(neg. charged) focuses e- stream on the output phosphor

A

electrostatic lens

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10
Q

total D XR tube travels during actual exposure; there’s an inverse relationship btw exposure angle & section thickness

A

exposure angle/amplitude

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11
Q

how do pi lines appear on XR?

A

small marks on XR ≈ 3.1416” apart; appears perpendicular to the film’s direction of travel

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12
Q

Slip ring technology ?

A

replaced tangling high tension cables

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12
Q

acceptable level of distortion in primary class devices is

A

2%

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13
Q

2nd gen beam?

A

fan

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13
Q

the region of interest illustrated in the img and is reconstructed from the complete set of raw data

A

display/reconstruction FOV

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14
Q

centering indicator: must be accurate to

A

1% of SID

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15
Q

What is the device used to measure screen film contact?

A

wire mesh test (performed semi-annually)

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16
Q

detectors for 4th gen CT?

A

Multiple encircle pt; fixed ring of 4800 detectors

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16
Q

total D XR tube travels

A

tomographic angle/amplitude

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16
Q

mammography uses an anode angle of

A

23º

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16
Q

electronic noise in digi mammo can be reduced by

A

cooling detector

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17
Q

splits body into equal front and back halves

A

midcoronal

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18
Q

input phosphor f(x)?

A

converts XR energy into vis. light

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20
Q

Learn how to calculate pitch.

A

pitch = length of table travel per rotation/slice thickness

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21
Q

detectors for 2nd gen CT?

A

Multiple ≈ 30+ along a line

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22
Q

responsible for selecting the medical physicist & mammographers responsible for QC; responsible for supervising QA; supervisingQA program; oversee activities of team members; supervising pt communication/tracking

A

radiologist

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24
Q

tube movement for 3rd gen CT?

A

tube & detectors rotate; rotate continuously around the pt for 360º

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26
Q

scan T for 1st gen CT?

A

4.5-5 min./img

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27
Q

what causes static marks?

A

from friction or humidity lower than 40% caused by buildup of e-’s in emulsions

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28
Q

Advantages of volume scanning

A

multiplanar reconstruction shorter scan T reduced motion artifacts

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29
Q

Who invented CT?

A

Godfrey Hounsfield

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30
Q

Use of Breast compressions on mammography

A

use increases contrast & spatial res. lowers pt dose reduces motion blur reduces superimposition reduces focal spot blur

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31
Q

performs annual performance eval.’s of equipment, consults w/ mammographers concerning QC, review QC records to check for compliance; avg glandular dose to mammo pt’s must be tested annually by medical physicist

A

medical physicist

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32
Q

QA?

A

deals w ppl

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33
Q

How can you improve the spatial resolution on a mammographic image?

A

breast compression

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34
Q

QC limit for film illuminator

A

should not vary more than 10% (viewbox illumination)

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35
Q

volume scanning aka?

A

helical/spiral CT

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36
Q

how many detectors for 1st gen?

A

1; single

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37
Q

scan T for 3rd and 4th gen CT?

A

< 1 sec./img

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37
Q

mammography uses a tube tilt of

A

6º

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38
Q

frontal plane

A

coronal

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39
Q

What is the true size of a lesion if its magnified img measures 3 cm and the magnification factor is 1.5?

A

2.0 cm

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40
Q

What control the slice thickness of a tomographic image?

A

tomographic angle determines section thickness as angle increases, tomographic section becomes thinner (decreases)

42
Q

What are the devices used to measure focal spot size?

A

pinhole camera star camera slit camera

43
Q

mammo QC team?

A

radiologist, medical physicist, mammographer

44
Q

a process where scattered rad. in the form of XRs, e-’s, and particularly light can reduce the contrast of the I.I. tubes

A

veiling glare

46
Q

single picture element of the matrix 2D representation of the 3D volume of tissue in CT slice

A

pixel

47
Q

What are the various types of static marks?

A

tree, crown smudge

48
Q

median plane

A

sagittal

50
Q

small display FOV (on magnification)

A

(zoom) restricts area of interest & displays anatomy larger; increases noise & in-plane spatial res.

51
Q

f(x) output phosphor

A

interaction w e- stream produces light photons of much greater intensity than was produced at the input phosphor

51
Q

Mammography currently uses ?

A

single-emulsion film

52
Q

What is quantum mottle?

A

(noise) grainy img from insufficient mAs

54
Q

used to perform a qualitative eval. of the luminance response (refers to relationship tw displayed luminance & input values of a standardized display system) of a digi. display device; evaluated from D of 30 cm

A

TG 18 CT

55
Q

determines area over which projection data is collected; determines # of detectors collecting data for particular scan

A

scan FOV

56
Q

spatial res. is limited by

A

pixel size

57
Q

purpose of QA program is to maintain max. ___________ w min. ___________

A

quality mammograms; pt dose

58
Q

tube movement for 1st gen CT?

A

tube & detector move linearly/ then rotate 1º - arc 180º; translate rotate scanning motion

59
Q

(CT) scout aka?

A

scanogram or topogram

60
Q

imaginary pivot point that the XR tube & IR move around; area of interest

A

fulcrum

61
Q

range of CT #s that are displayed shades of gray controls the displayed img contrast

A

window width (WW)

62
Q

QC limit for backup timer

A

should terminate the exposure at 6s or 600 mAs, whichever occurs first (or 1.5x’s original exposure)

63
Q

calculate total brightness gain

A

total brightness gain = magnification gain x flux gain

65
Q

how do guide show marks appear on XR?

A

thin lines on the leading/trailing edge of a film; parallel to the direction of film travel thru processor

66
Q

attracts e-’s emitted by neg. photocathode

A

anode

67
Q

QC?

A

deals w instrumentation & equipment; monitoring of equipment performance

68
Q

photopic vision

A

use cones for daylight vision (intense light levels); cones have better visual acuity (perceive smaller objects better) & contrast perception than rods

69
Q

splits body into equal L and R halves

A

midsagittal

70
Q

photocathode materials?

A

cesium and antimony compounds

70
Q

calculate minification gain

A

minification gain = diameter of input phosphor^2/diameter of output phosphor^2

72
Q

Qc limit for collimation light

A

misalignment should not exceed 2% of SID

73
Q

scan T for 2nd gen CT?

A

20 sec./img

74
Q

What is a scout in CT?

A

preliminary img of the area being examined

74
Q

materials for input phosphor?

A

cesium iodide crystals

75
Q

factors that affect spatial res. (amount of detail present in an img)

A

phosphor layer thickness pixel size diameter of laser beam

77
Q

the first rad. exam of the breasts obtained before 40 yrs use it for comparison of all future mammograms

A

baseline mammography

78
Q

detectors for 3rd gen CT?

A

Multiple > 750++ along a curve; 960 detectors (curved array)

79
Q

What causes PI lines?

A

bc of dirt/chem stain on a roller sensitizes the emulsion

80
Q

splits body into top and bottom halves

A

axial - horizontal plane

82
Q

What is volume scanning

A

XR tube rotates continuously around the pt as the pt/table increment through the gantry at selected speed

83
Q

identify pincushion & barrel-like (geometric - affect relative size/shape of img features) distortions; used to eval. display res

A

TG18 QC

84
Q

where XR & IR move about a fulcrum to obtain an img of a specific layer of tissue or an object that is superimposed by other tissue/objects; blurs structures above/below a specific plane

A

tomography

85
Q

QC limit for exposure reproducibility

A

rad exposure should be reproducible to w/in 5%; output rad intensity should not vary more than 5%

86
Q

distance indicator: must be accurate to

A

2% of SID

86
Q

a min. of ____ mammograms must be included in a repeat analysis

A

250

88
Q

mammo done symptomatic pt’s or ones w high risk factors (family hx) 2-3 views

A

diagnostic mammography

89
Q

acceptable level of distortion in secondary class devices is

A

5%

91
Q

plane in which target anatomy is clear/in focus; controlled by level/height of the fulcrum

A

focal plane: (object plane)

91
Q

factors that control the brightness of the image in fluoroscopy

A

anatomy being examined kVp mA

92
Q

it is essential that a small focal spot be used in ____________ to preserve img detail

A

magnification radiography

93
Q

What are the formulas used for calculating magnification factor?

A

MF = img size/object size MF = SID/SOD

94
Q

calculate flux gain

A

flux gain = # of output light photons/# of input XR photons

96
Q

scotopic vision

A

use rods for night vision (low light levels)

97
Q

tube movement for 4th gen CT?

A

only tube rotates; rotate continuously around pt for 360º

98
Q

tomography w a tomographic angle of 10º or less, section thickness will be very large; used when the subject contrast is so low that a thin section tomo would result in poor img; most often in chest & renal exams

A

zonography

99
Q

structure of an image intensifier (I.I.)

A
  1. Metal Housing 2. Vacuumed Glass/Metal Envelope 3. Input Phosphor 4. Photocathode 5. Electrostatic Lens 6. Anode 7. Output Phosphor
101
Q

volume element; depth of a voxel is defined by the ‘slice thickness’

A

voxel

102
Q

If the img size of an object is 3 cm and the magnification factor is 1.5 then what is the actual size of the object?

A

2.0 cm

103
Q

the reduction in brightness at the periphery of an img

A

vignetting

105
Q

1st gen beam?

A

pencil

106
Q

QC limit for exposure timer accuracy

A

accuracy of 5% of the indicated exposure T for exposures greater than 10 ms; accuracy of 20% for exposure T less than 10 ms

108
Q

trajectories used: (5) (tomography)

A

linear - least blurring of structures circular elliptical trispiral - produce max. blurring of unwanted structures hypocycloidal

109
Q

disadvantage of mag rad:

A

increased pt dose (2x’s dose)

110
Q

photocathode f(x)

A

emits e-’s when stimulated by light from the input phosphor (photoemission)

111
Q

3rd gen beam?

A

fan

113
Q

Target materials used in mammography and its advantages?

A

Molybdenum (Mo): 19 keV; used for smaller breasts Rhodium (Rh): 23 keV; increased penetration so used for thicker/larger breasts; (both reduce scatter)

114
Q

The radiologist has requested that the images for a cerebro angio be magnified 100%. where would you set the SOD of the head if the SID is set at 20”?

A

10”

115
Q

tube movement for 2nd gen CT?

A

tube & detectors move linearly/ then rotate 5º + - arc 180º; rotate translate scanning motion

116
Q

mammo done on asymptomatic pt’s 50+ yrs min. of 2 views

A

screening mammography

117
Q

QC limit for exposure linearity:

A

must be w/in 10% of the adjacent mA stations; mR/mAs value must be w/in 10% of adjacent mA stations

118
Q

CT numbers, what number represent air, water, bone?

A

air: -1000 water: 0 bone: +400 —> +1000

119
Q

large display FOV (on magnification)

A

displays anatomy smaller; reduces noise & in-plane spatial res.

120
Q

used for the measurement of the res. of a display system helps point out any gross deviation in luminance adjustment

A

SMPTE pattern

121
Q

materials for output phosphor?

A

zinc cadmium sulfide

122
Q

What causes guide shoe mark?

A

caused by misalignment of the processor turnaround assembly (processing artifact)

123
Q

max. non-uniformity of a display device should be

A

< 30%

Radiologic Technology (5 decks)

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