Physics Ch 5 Mammo

Question 1

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

• kVp
• beam spectrum
• anode

Answer 1

• lower kVp
• use nearly monoenergetic beam
• anode: molybdenum or rhodium

Question 2

which anode target & filter combination should never be used?

Answer 2

Rh/Mo

Question 3

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

Answer 3

Rh/Rh –> higher energy than Mo/Mo

Question 4

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

Answer 4

• Tungsten/Rho
• Tungsten/Silver

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

Question 5

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

Answer 5

• avg energy inc

- contrast dec

Question 6

focal spot size?

• mammo
• gen XR

Answer 6

• mammo: 0.1 & 0.3 mm

- gen XR: 0.6 & 1.2 mm

Question 7

mammo vs gen XR –> difference in…

• focal spot size
• mA
• exposure time

Answer 7

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

Question 8

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

• mAs
• inc kVp
• dec kVp

Answer 8

dec kVp

Question 9

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

Answer 9

dec focal spot size

Question 10

XR tube –> window material?

• gen XR
• mammo XR

Answer 10

• gen XR –> pyrex glass

- mammo XR –> beryllium

Question 11

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

Answer 11

dec dose & scatter

Question 12

grid –> pro? con?

Answer 12

• remv scatter –> improve contrast

- inc dose

Question 13

mammo vs gen XR –> difference in grid ratio?

Answer 13

mammo –> lower grid ratio

Question 14

mammo XR –> magnification –> goal?

Answer 14

improve detection of calcifications

Question 15

mammo XR –> how magnified?

Answer 15

• dec source to obj distance

- inc obj to detector distance

Question 16

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

Answer 16

no grid –> air gap act as grid

Question 17

mammo XR –> mag view –> change in…

• focal spot?
• mA?
• exposure time?

Answer 17

• focal spot –> smaller
• mA –> dec
• exposure time –> inc

Question 18

what is air kerma?

Answer 18

XR density –> #XRs per unit of space

Question 19

mammo XR vs gen XR –> difference?

• optical density
• receptor air kerma

Answer 19

mammo XR:

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

Question 20

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

Answer 20

photoconductors (selenium)

Question 21

digital mammo –> MQSA requirement for line pair?

Answer 21

digital –> no specific line pair requirements

Question 22

dark noise –> caused by?

Answer 22

electronic fluctuations w/in detector element

Question 23

digital mammo –> artifacts? (2)

Answer 23

• ghosting

- pixels gone bad

Question 24

what is ghosting artifact?

Answer 24

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

Question 25

digital breast tomosynthesis --> advantage over conventional mammo?

Answer 25

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

Question 26

digital breast tomosynthesis vs conventional mammo --> difference? - mass margin & shape - mass density - fat mass

Answer 26

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

Question 27

what is positive predictive value?

Answer 27

positive study --> actually have breast cancer

Question 28

positive predictive value --> formula?

Answer 28

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

Question 29

what is PPV1?

Answer 29

screening mammo --> positive

Question 30

what is PPV2?

Answer 30

recommend bx

Question 31

what is PPV3?

Answer 31

bx --> positive

Question 32

mammo workstation --> minimum #megapixels?

Answer 32

3 MP

Question 33

MQSA --> processor QC --> how often?

Answer 33

daily

Question 34

MQSA --> darkroom cleanliness --> how often?

Answer 34

daily

Question 35

MQSA --> viewbox conditions --> how often?

Answer 35

wkly

Question 36

MQSA --> phantom eval --> how often?

Answer 36

wkly

Question 37

MQSA --> repeat analysis --> how often?

Answer 37

qtrly

Question 38

MQSA --> compression test --> how often?

Answer 38

semi-annual

Question 39

MQSA --> darkroom fog --> how often?

Answer 39

semi-annual

Question 40

MQSA --> screen film contrast --> how often?

Answer 40

semi-annual

Question 41

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

Answer 41

- grid --> 3 mGy | - no grid --> 1 mGy

Question 42

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

Answer 42

240