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PHYS 216 > Knobology > Flashcards

Knobology Flashcards

1
Q

What is the best way to optimize an ultrasound machine?

A

Read the user manual

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2
Q

What are presets for?

A

To optimize an image for the assumed scanning conditions

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3
Q

What do presets help avoid?

A

Bio effects

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4
Q

When using presets it is important to?

A
  1. Use the correct one for the type of exam

2. Make adjustments beyond the preset

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5
Q

What is important to know about transducer selection?

A
  1. The probe must be plugged in to select it

2. Never unplug an active plug (damage)

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6
Q

What is multihertz?

A

Numerical gauge on frequency selection.

(On phillips machines = res/gen/pen

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7
Q

What is harmonics?

A

When it is activated the machine sends out a frequency but receives double that frequency when the echos return.

(2Mz out, 4 MHz back in)

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8
Q

When should harmonics be used?

A

Whenever the penetration allows

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9
Q

What is Coded Harmonics?

A

Allows for excellent penetration with higher frequencies

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10
Q

What is transmit power?

A

The intensity of the ultrasound beam transmitted into the patient

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11
Q

Increasing the transmitted power (intensity) will change what?

A
  1. Decrease/improve the SNR (signal to noise ratio)

2. Enhance sensitivity

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12
Q

When you turn on your machine, what will the transmit power be set at?

A

100%

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13
Q

In what situation would you turn the power down?

A

When using doppler on a fetus because doppler puts out more power

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14
Q

What does Gain do?

A

It amplifies all of the returning echos during signal processing

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15
Q

What unit is gain expressed in?

A

Decibels

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16
Q

What is TGC?

A

A receiver gain that adjusts the echos according to time delay (or depth).

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17
Q

How does changing depth effect TGC?

A

You have to readjust, changing depth changes the TGC

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18
Q

What knobology uses the range equation?

A

TGC

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19
Q

Do Gain and TGC improve the SNR?

A

No

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20
Q

How is TGC expressed?

A

As a slope.

An increase in slope is an increase in amplification.

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21
Q

What is the golden rule of TGC’s?

A

Never move one at a time

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22
Q

What is lateral gain?

A

Found on cardiac equipment, used to compensate for side-to-side non-uniformities in brightness due to different pathways

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23
Q

How does lateral gain differ from TGC?

A

It alters echo intensities from individual scan lines on the periphery of the image

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24
Q

What does focus do?

A

It adjusts the depth of near field to improve the lateral resolution at the area of interest.

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25
Q

What happens if multiple foci are used for a larger field?

A

The frame rate is significantly reduced (takes more time = choppier image).

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26
Q

What is co-processing?

A

A means of helping reduce the impact of the reduction in frame rate

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27
Q

What does focus impact?

A

Frame rate.
It gives better resolution at multiple points.

(We don’t use on something moving)

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28
Q

What does depth do?

A

Ability to maximize the field of view, as depth changes the echo info is redistributed to fit the monitor.

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29
Q

What does depth influence?

A

Frame rate and line density since the speed of sound is constant.

30
Q

What is line density?

A

The density of scan lines in an image (the sound going and coming back).

31
Q

How does changing the depth effect line density?

A

An decrease in depth will increase the line density,

32
Q

What happens at a large depth?

A

The lines are less dense (spread out) which equals less information because the machine “makes up info” to fill in the gaps.

33
Q

What is dynamic range?

A

A form of compression that reduces the number of shades of grey to increase the contrast of the image.

34
Q

What happens when Dynamic Range is reduced?

A

Weak echos and noise are removed

35
Q

What is another name for Dynamic Range on other machines?

A

Compression

36
Q

How many shades of grey does the machine have? How many can the human eye see?

A

256 machine

100 human eye

37
Q

Why is it important to have dynamic range set properly?

A

If wrong, it can prevent the visualization of small low-contrast structures (decreases tissue differentiation).

38
Q

What is the limit of dynamic range?

A

Bi-stable (black and white)

39
Q

What is freeze?

A

Control that stops the transducer from sending out sound, the machine continually writes the last available frame to display

40
Q

What does freeze eliminate?

A

Real time blurr from capturing a moving image

41
Q

What is cineloop?

A

The systems memory allows for a number of frames to be saved until the image is frozen

42
Q

What does cineloop allow?

A

Frame by frame analysis in order to select the best image

43
Q

How many frames does a machine store with cineloop?

A

Hundreds

44
Q

What is sector width?

A

The ability to reduce the field of view by firing fewer scan lines

45
Q

What types of probes have the option of sector width?

A

Curved linear and echo

46
Q

What does sector width effect?

A

Decreasing the sector width will:

  1. Decreases the area
  2. Improves line density (concentrates the sound)
  3. Improve frame rate (spatial resolution)
47
Q

What is dual image?

A

The ability to split the screen when demonstrating certain anatomy or pathology

48
Q

Why was dual image invented?

A

As a cost saving measure when images were on film

49
Q

What is persistence?

A

Reduces noise by applying temporal averaging to individual pixels

50
Q

How does the operator control persistence?

A

By selecting the number of frames being averaged so that the image is more consistent

51
Q

How does increasing persistence effect frame rate?

A

Increasing persistence decreases the frame rate

52
Q

When is persistence not used?

A

For cardiac applications because we want a high frame rate in order to see small movements.

53
Q

What is an example of calculations available on the machine?

A

Specific OB measurements and calculations available in an OB preset

54
Q

What is zoom?

A

Magnifies the image, there are two diff types of zoom

55
Q

What is write zoom?

A

Magnifies the image before it is written to memory (the zoom before you freeze).

“Optical zoom = the good one”

56
Q

What is read zoom?

A

Magnifies the image after the image is committed to the systems memory (after image is frozen)

“Digital zoom = bad quality”

57
Q

What type of zoom improves resolution?

A

Write zoom (magnifies before freeze)

Resolution is lost with read zoom

58
Q

What are maps?

A

A way of redistributing the shades of grey displayed so that emphasis is given to particular values (used to brighten low level echos but ignore echoes above a threshold or vice versa)

59
Q

Can maps be applied after freeze?

A

Yes

60
Q

What is video invert?

A

Used to detect subtle changes in echotexture, fluid can be seen as white and soft tissue as black.

Not common practice

61
Q

What is image invert?

A

Image is inverted top to bottom or left to right by changing the horizontal/vertical orientation of the image on the diplay

62
Q

When is image invert used?

A

For intervention.

For a biopsy the performing physician may prefer to see the needle coming from a specific angle

63
Q

What are hidden functions?

A

Some applications maybe be hidden until times of need

64
Q

What is an example of a hidden function?

A

Biopsy needle overlay (to assist with intervention)

65
Q

What is pre-processing?

A

Any control that can be adjusted before the image is frozen (committed to memory).

66
Q

What is post-processing?

A

Controls applied to the image after it is frozen

67
Q

What control is both post and pre processing?

A

2 D Gain

68
Q

What are the doppler controls?

A
  • Gain
  • Scale (PRF)
  • Steer
  • Invert
69
Q

What is compound imaging?

A

A combination of beam steering and frame averaging that can improve SNR and help eliminate artifacts

70
Q

What is another name for compound imaging? (On our machine?)

A

Sono CT

71
Q

Why should compound imaging not be used all the time?

A

Some artifacts are useful in diagnosis so it is not helpful to always eliminate them.

(Kidney stone: we need to see the shadows)

72
Q

What is panoramic imaging?

A

If an area of interest is larger than the transducer face, panoramic allows the system to store multiple frames of a sweep and display the entire area

PHYS 216 (11 decks)

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