Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

2016FA PHYSICS (K. Greene) > QUIZ #6 > Flashcards

QUIZ #6 Flashcards

You may prefer our related Brainscape-certified flashcards:
Physics 101 flashcards AP® Physics flashcards
1
Q

Is mammography high or low dose?

A

High dose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is our #1 challenge in mammography?

A

Ability to see structures w/ good contrast resolution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What technical factors can change to separate tissues in mammography?

A

Lower the kVp

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Where is the control panel in mammography?

A

Directly in the room because of less kVp, less shielding is needed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is a safety feature on the mammography control panel that ensures you’re behind the protective barrier?

A

Two buttons need to be pushed together so you’re not leaning around the protective barrier

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What one thing must we have in mammography to see calcifications?

How is it achieved?

How should calcifications look?

A

We must have magnification

Achieved by increased OID

Calcifications = the less number the better, and if they’re all similar shapes, that’s better, but the more crazy different shapes we have, something not so good is happening

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What generator is used for mammography?

A

High frequency generator - for reproducibility

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the minimum mag mode for mammography

A

Minimum of 1.4 - 2.0 mag mode

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

About what percent of mammography is digital?

A

~75% is digital (CR/DR)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the focal spot sizes for mammography?

A

Large FSS = 0.3mm

Small FSS = 0.1mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What material is the anode in mammography made of?

A

Moly, Rhodium, or Tungsten

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What material is the filter in the mammography x-ray tube made of?

A

Moly, Rhodium, or Silver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What material is the window in the mammography x-ray tube made of?

A

Beryllium (Z# 4)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What do we want in mammography? A larger or smaller FSS? Why?

A

Smaller focal spot size for better spatial resolution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Do we need high or low energy x-rays for mammography?

A

Lower energy x-rays to be able to image really fatty breasts at low kVp

Higher energy x-rays for denser (young and hormone replacement) breasts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Average kVp for mammography?

A

20-35 kVp

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Average mAs in mammography?

mA and seconds?

A

35-800 mAs

50-200 mA @ 0.5-4 seconds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Average SID for mammography?

A

50-80cm (65cm/25” common)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How many cells does AEC have in mammography? What is their range of motion?

A

1 cell, moveable from chest wall to nipple

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What does AEC in mammography control?

A

kVp, mA, and seconds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the typical breast thickness?

What is the ratio of fat/glandular?

A

4.5cm thick

50/50 mix of fat and glandular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Would you use AEC under a silicon implant?

A

No because it will offset the exposure (like a missing lung in an x-ray)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Where is the CR placed in mammography on the patient?

What does this prevent?

Anode heel effect?

A

CR placed at the chest wall

Prevents tissue from being projected off the image receptor into the chest cavity . If CR is straight (parallel) with chest wall, the beam will diverge anteriorly and ensure all anatomy is imaged

Anode heel effect = anode side towards nipple and cathode towards thicker portion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are mammography grids made of?

A

lead strips with carbon interspaces

25
Q

What kind of pattern are used in mammography grids?

A

high transmission cellular (HTC / honeycomb)

26
Q

What is the ratio of a mammography grid?

A

4:1

27
Q

Are grids used in magnified mammography images? Why?

A

No, because of air gap

28
Q

What is the FoV of mammography?

A

Collimation set to the area of the IR

29
Q

Magnification of mammography must have a minimum of what?

A

1.4 = minimum magnification

30
Q

How many pounds of force is used in mammography compression?

How does this affect image quality?

A

25-45 lbs compression

Improves image quality w/ less superimposition, decreases OID, and decreases patient dose, less scatter

31
Q

What are the three types of IR in mammography?

A

Film/Screen

Digital DR

Computed CR

32
Q

What processing factors can be adjusted in mammography?

A

Window width + level

Contrast

Inverted image

33
Q

What type of generator is used in IR and mammography?

A

o Mammography = high frequency generator

o IR = high frequency generator

34
Q

What level of mag is needed in mammography and why?

A

o Must have a minimum mag mode of 1.4 – 2.0

o “In mammography, we have to be able to do magnification, by increased OID, to see small calcifications clearly (how many are there and what are their shapes. The less number the better, and if they’re all similar shapes, that’s better. But the more crazy different shapes we have, something not so good is happening.”

35
Q

What are the FSS in IR and mammography?

A

o Mammography = 0.1, 0.3mm FSS

o IR = 0.3, 1.0mm FSS

36
Q

What type of target material is used in both and why?

A

o Mammography = Molybdenum, Rhodium or Tungsten “because they produce the lower-kilovoltage x-rays needed for mammograms, but still have high melting points and good electrical conductivity”

37
Q

• What is unique about AEC in mammography?

A

o AEC in mammography automatically adjusts all three: kVp, filter, mA, and seconds and contains 1 cell behind the cassette, moveable from chest wall to nipple

38
Q

• Where is CR in mammography and why

A

o CR is at chest wall not center of the breast.

o CR at chest wall prevents tissue from being projected off the image receptor into the chest cavity.

o If CR is straight (parallel) with chest wall, the beam will diverge anteriorly and ensure all anatomy is imaged

o “Anode heel effect, anode side towards nipple and cathode towards thicker portion”

39
Q

• What type of grid do we use in mammography

A

o Lead strips with carbon inter-space

o High transmission cellular (HTC) (honey comb)

o 4:1 ratio

o Not used in magnification images

40
Q

• What are the advantages of compression in mammography?

A

o “Less dose and less super imposition and decreases OID (which improves image quality)“ ”less scatter, closer to IR, less mAs”

41
Q

• What types of digital imaging are used in mammography- CR/Direct/Indirect- some of them or all of them?

A

o “Most are direct systems, better resolution, smaller pixels”

o Both are used

42
Q

• What is tomosynthesis, why is it so great?

A

o 3D mammography: tube moves while the detector is stationary; breast is compressed; traditional images (CC + MLO) are taken.

o Most often used when additional views are needed to rule out mass or for patients with dense breasts.

o “Gets an average image out of slices of images” — Kerry

o Tomosynthesis makes it easier to detect mass growth, otherwise undetectable by regular mammography.

o Disadvantage is that insurance does not cover the cost of tomosynthesis and more dose — Kerry

43
Q

• What procedures do we do in IR?

[6 items]

A

o Angiography- imaging of vessel after injection of contrast material (contrast directly into vessel)

o Angioplasty- balloon is placed within a vessel to expand a narrowed area

o Thrombolysis- pharmaceuticals are injected into a vessel at the site of a clot, dissolves clot

o Embolization- blood supply is terminated, in order to kill tissue

o Stent- plastic/metal tubes are placed to keep specific areas patent (brace that keeps vessel open)

o Biopsies- tissue is removed from patient for diagnosis

44
Q

• What types of digital detectors are used in IR?

A

o “About 80% of IR systems are flat panel detectors”

  • Cine = used in cardiac catheritization, hi dose, hi quality, 16 or 35mm film
  • Charged Coupled Device = CCD, converts light to digital video signal with use of an ADC.
  • Flat Panel Detector = same panel as DR, sampled at a higher rate for cine loop.
45
Q

• CR and DR speed is different from traditional film, what do we do to adjust for that- how is the 15% rule utilized and why?

A

o “Given all of this data, it is strongly recommended that medical imaging departments adopt a policy of implementing at least one 15 percent step increase in kVp from the conventional kVp levels used for film/screen radiography, accompanied by a halving of the mAs, and that this approach should be applied “across the board” for all techniques, with the possible exception of chest procedures.” p. 571

46
Q

• Using the 15% rule allows for a _____% decrease in exposure to the patient

A

o “By applying the 15 percent rule in a single step, surface exposure can be reduced by one-third, to 65-70 percent, and absorbed dose to the patient can be reduced even more.” p 571

47
Q

• What one body part might not be able to utilize the 15% rule due to very low mAs to begin with

A

o “Chest exams tend to be more vulnerable to mottle than other procedures, likely due to the very low mAs values associated with typical chest techniques” p 571

48
Q

• kVp is considered to be what type of factor in contrast now

A

o “the word “control” is too strong to describe the relationship between kVp and digital image contrast; the notion that kVp is the controlling factor for contrast (a popular concept with conventional radiography) should be avoided. Rather, in the digital age, kVp should be thought of as one of several factors simply affecting the contrast of the initially displayed digital image” p 572

49
Q

• What is dose creep and why does it happen

A

o “Dose creep has become an issue with computerized systems due to the illegitimate fear of image mottle and the ability of CR and DR to correct the image for overexposure” p 587

50
Q

• If an image is noisy in DR/CR would you increase kVp or mAs

A

o “No amount of mAs will ever compensate for inadequate kVp … there must be enough good signal to overwhelm the presence of noise, such as quantum mottle, within the exposure process” p 547

o “Higher kVp levels display more anatomical data and lower patient dose, and the radiologists can window higher image contrast as desired using computer display software” p 577

51
Q

• Pre-fogging (background) shows where in the histogram- whites or darks, can it be removed digitally

A

o “”Pre-fogging” of a CR cassette creates a spike of gray densities at the left end of the image histogram and leaves no “blank” white pixels present. This pulls the location of both the S-MIN and S-AVE to the right, skewing rescaling and the EI. The corrupting effects of this light from fog can remain uncorrected, resulting in a poor final image.” p 579

52
Q

• Scatter (from imaging) shows where in the histogram- whites or darks, can it be removed digitally

A

o Scatter is dark (right on histogram) and it can be removed digitally p575

53
Q

• What body parts have a histogram with no tails, what have just a high density tail, and what example had a low and high density tail

A

o No tails = abdomen

o High density tail = chest

o Low and high density tail = extremity

54
Q

• What are the three values that are assigned in the histogram analysis? What do they define and what does the S-ave provide to us

A

o S-MIN, S-MAX, S-AVE

  • S-MIN = “the lightest non-zero pixel count” p 482
  • S-MAX = “the darkest density (highest pixel value) within the anatomical body part” p 483
  • S-AVE = “the average density within the anatomy, or average pixel value for the main lobe of the histogram, between the S-MIN and S-MAX.” p 483
55
Q

• What unique issue does CR have with grids and how do we avoid it

A

o “With CR imaging, the Moiré artifact is actually much more likely to occur. This “electronic” version is called an aliasing artifact. It is due to the Nyquist frequency, the frequency at which the CR reader scans the plate line by line, interacting with the grid strips, which also have a frequency” p 580

o “When the Moiré artifact is a recurring problem with a CR reader, either new grids must be purchased with a different frequency (grid lines per inch), or the scanning frequency of the CR reader would have to be changed … special multi-hole grids are available which solve this problem” p 580

56
Q

• Why is collimation so important in CR and proper orientation of the exposed field?

A

o “Exposure indicator errors are likely unless at least 30 percent of the imaging plate is exposed” p 583

57
Q

What are the following post processing methods?

Tissue Equalization – ?

Magnification – ?

Image Inversion – ?

Annotation and Measurement – ?

CAD – ?

A

What are the following post processing methods?

Tissue Equalization – take area that was oversaturated and bring it back to normal

Magnification – magnifying glass on your screen, we do 4 views, the CC and oblique,

Image Inversion – blacks and whites inverted

Annotation and Measurement – textbox for writing stuff

CAD – an algorithm and says this is a mass, cysts, normal, etc, it gets smarter as it sees more images

58
Q

• Scatter is mainly due to what factor out of - FOV, PT size and kVp used (different train of thought than traditional)

A

o FOV affects scatter which is why we collimate and patient/ part size affects as well, larger patient/part, more scatter; the kVp doesn’t affect as a primary source of scatter anymore, it is now considered a secondary source of scatter

2016FA PHYSICS (K. Greene) (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions