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CORE > Physics Ch 5 Mammo > Flashcards

Physics Ch 5 Mammo Flashcards

1
Q

mammo XR vs gen XR –> differences? (3)

  • kVp
  • beam spectrum
  • anode
A
  • lower kVp
  • use nearly monoenergetic beam
  • anode: molybdenum or rhodium
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2
Q

which anode target & filter combination should never be used?

A

Rh/Mo

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3
Q

what anode target & filter combination is used for denser breasts?

A

Rh/Rh –> higher energy than Mo/Mo

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4
Q

some digital systems –> use anode target & filter combination for inc penetration/lower dose? (2) Con? (1)

A
  • Tungsten/Rho
  • Tungsten/Silver

dec contrast –> but can improve contrast w post-processing

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5
Q

mammo filter –> inc k-edge energy –> what happen to beam avg energy? contrast?

A
  • avg energy inc

- contrast dec

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6
Q

focal spot size?

  • mammo
  • gen XR
A
  • mammo: 0.1 & 0.3 mm

- gen XR: 0.6 & 1.2 mm

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7
Q

mammo vs gen XR –> difference in…

  • focal spot size
  • mA
  • exposure time
A
  • focal spot size –> smaller
  • mA –> lower
  • exposure time –> longer
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8
Q

what factor is changed to maximize detection of solid breast mass in the background of normal breast parenchyma?

  • mAs
  • inc kVp
  • dec kVp
A

dec kVp

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9
Q

what factor is changed to maximize detection of low grade ductal malig (no assoc mass) on background of normal breast parenchyma?

  • mAs
  • inc kVp
  • dec focal spot size
A

dec focal spot size

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10
Q

XR tube –> window material?

  • gen XR
  • mammo XR
A
  • gen XR –> pyrex glass

- mammo XR –> beryllium

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11
Q

mammo –> compress breast tissue –> #1 advantage?

A

dec dose & scatter

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12
Q

grid –> pro? con?

A
  • remv scatter –> improve contrast

- inc dose

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13
Q

mammo vs gen XR –> difference in grid ratio?

A

mammo –> lower grid ratio

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14
Q

mammo XR –> magnification –> goal?

A

improve detection of calcifications

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15
Q

mammo XR –> how magnified?

A
  • dec source to obj distance

- inc obj to detector distance

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16
Q

mammo XR –> mag view –> use grid? why?

A

no grid –> air gap act as grid

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17
Q

mammo XR –> mag view –> change in…

  • focal spot?
  • mA?
  • exposure time?
A
  • focal spot –> smaller
  • mA –> dec
  • exposure time –> inc
18
Q

what is air kerma?

A

XR density –> #XRs per unit of space

19
Q

mammo XR vs gen XR –> difference?

  • optical density
  • receptor air kerma
A

mammo XR:

  • optical density –> higher
  • receptor air kerma –> higher
20
Q

digital mammo –> what detector type has best spatial resolution?

A

photoconductors (selenium)

21
Q

digital mammo –> MQSA requirement for line pair?

A

digital –> no specific line pair requirements

22
Q

dark noise –> caused by?

A

electronic fluctuations w/in detector element

23
Q

digital mammo –> artifacts? (2)

A
  • ghosting

- pixels gone bad

24
Q

what is ghosting artifact?

A

high attenuating obj –> ie lead –> placed in beam –> burned into detector –> residual image from prior exposure

25
Q

digital breast tomosynthesis –> advantage over conventional mammo?

A

dec effects of tissue superimposition –> inc sens & spec –> reduce false positives

26
Q

digital breast tomosynthesis vs conventional mammo –> difference?

  • mass margin & shape
  • mass density
  • fat mass
A

tomo:
- margin & shape –> improved
- density –> dec
- fat mass –> on tomo, cancer may be shown to engulf fat –> intralesional fat –> still recommend bx

27
Q

what is positive predictive value?

A

positive study –> actually have breast cancer

28
Q

positive predictive value –> formula?

A

positive exam w CA / (positive exam w CA + positive exam w/out CA)

29
Q

what is PPV1?

A

screening mammo –> positive

30
Q

what is PPV2?

A

recommend bx

31
Q

what is PPV3?

A

bx –> positive

32
Q

mammo workstation –> minimum #megapixels?

A

3 MP

33
Q

MQSA –> processor QC –> how often?

A

daily

34
Q

MQSA –> darkroom cleanliness –> how often?

A

daily

35
Q

MQSA –> viewbox conditions –> how often?

A

wkly

36
Q

MQSA –> phantom eval –> how often?

A

wkly

37
Q

MQSA –> repeat analysis –> how often?

A

qtrly

38
Q

MQSA –> compression test –> how often?

A

semi-annual

39
Q

MQSA –> darkroom fog –> how often?

A

semi-annual

40
Q

MQSA –> screen film contrast –> how often?

A

semi-annual

41
Q

breast phantom –> dose limit w grid? without grid?

A
  • grid –> 3 mGy

- no grid –> 1 mGy

42
Q

MQSA: last 2 yrs of training –> required to read how many mammo exams to be able to read mammos?

A

240

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