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Phys 254 > Module 2: Basic Instrumentation > Flashcards

Module 2: Basic Instrumentation Flashcards

1
Q

The Ultrasound systems converts the mechanical sound waves from the patient and converts them to what?

A

Electrical information

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2
Q

The converted voltages are processed by the machine to do what?

A

Reconstruct an image from the reflectors in the body

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3
Q

Once the voltages are processed by the machines to reconstruct an image from the reflectors in the body. What happens?

A

The voltages are stored and converted once again into the image we see on the monitor

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4
Q

What is the process for basic instrumentation?

A
  1. Tech
  2. Beam former
  3. Signal processor
  4. Image processor
  5. Display
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5
Q

What is the process for beam formers?

A
  1. Tech
  2. Transducer
  3. Amplifier
  4. ADC’s
  5. Echo delays
  6. Sum
  7. Signal processors
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6
Q

What is the other alternative process for beam former?

A
  1. Pulsed
  2. Pulse delay
  3. T/R
  4. Amplifiers
  5. ADC
  6. Echo delays
  7. Sum
  8. To signal processors
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7
Q

Digitizations of the voltage is crucial to maintain what?

A

The integrity of the data through the system

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8
Q

The process of digitizations involves what?

A

Converting the voltage into a binary number which is more stable

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9
Q

Digitizations can occur before or after what?

A

The echo delay in the beam former but the preferences is before to stabilize the signal early on

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10
Q

Signal processing involves what two steps?

A
  1. ADC
  2. The receiver
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11
Q

What is the function of the receiver?

A

It’s function is to process the returned echoes as analog voltages in preparation for display

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12
Q

There are five separate steps for the receiver preparing images for display. What are they?

A
  1. Amplification
  2. Compensation
  3. Compression
  4. Rejection
  5. Demodulation (includes rectification and smoothing)

Rac cd

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13
Q

Why must we use amplification for images?

A

Returning echos are weak and must be amplified if they are to make it through the circulatory of the machine

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14
Q

We further control the amount of amplification to do what?

A

To satisfy the need to brighten or darken the image

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15
Q

What is the control for amplification? and how is it expressed?

A

The control is the GAIN and is expressed in decibels typically in the range of 60 - 100dB

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16
Q

What are the two reasons why we need to use compensation for images?

A
  1. Sound attenuates as it travels and thus there is a need to compensate for it
  2. Similar signals from reflectors should have the same brightness regardless of how deep you image the reflector
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17
Q

What is the control for the compensation control?

A

TGC is the control responsible and is expressed in dB with a range of around 60dB

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18
Q

TGC can also be called what?

A

DGC

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19
Q

TGC usually operates in what increments?

A

1cm increments and can correct for the main bang artifact and attenuation in the far field

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20
Q

What is the compression control? And what is it used for?

A

The compression control is known as dynamic range, and it is the process of decreasing the difference between the smallest (reject level) and largest (saturation) amplitudes and is expressed in decibels

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21
Q

What is logarithmic amplification?

A

Where the gain is applied exponentially as a function of the input signal level and the result is the compression of the dynamic range

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22
Q

What is the rejection function also known as?

A

Threshold or suppression

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23
Q

What is the rejection control used for?

A

To eliminate or suppress low level echoes that may represent noise and therefore, improve the signal to noise ratio

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24
Q

What does rejection control help with?

A

Reduce the dynamic range and may or may not be operator controlled

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25
Q

What is the demodulation?

A

The process which converts the radio frequency (RF) signal into a video signal for monitor display

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26
Q

Demodulation is the two stage process that includes what?

A
  1. Rectification
  2. Smoothing
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27
Q

Rectification turns all negative portions of the signal into what?

A

Positive ones

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28
Q

What is the basic instrumentation path?

A
  1. TX
  2. Beam former
  3. Signal processor
  4. Image processor
  5. Display
29
Q

What is the image processing path?

A
  1. From signal processor
  2. Scan converter
  3. Pre processor
  4. Memory
  5. Post processor
  6. DAC
  7. To display
30
Q

What is scan conversion?

A

A simple function of the scan converter is to write the vertical acquired ultrasound data horizontally to memory

31
Q

The Scan converter or memory of a analog scan converter is similar to what?

A

CRT except that the phosphor face is replaced with a wafer or silicon called the dielectric matrix

32
Q

For analog scan converters electrons emitted by the filament, pass through what?

A

The deflection plates and strike the silicon wafer leaving a negative charge proportional to the amplitude of the signal strengths

33
Q

The electron beam of the analog converter moves across what?

A

Dielectric matrix in what is called a raster format

34
Q

What is pre- processing?

A

Simply any processing of the wave signal before it is transferred and stored to memory

35
Q

For preprocessing different ultrasound machines offer what?

A

Different processing

36
Q

What are some pre- processing functions?

A
  1. Receiver functions
  2. Maps
  3. Interpolation
  4. Edge enhancement
  5. Write zoom
  6. Persistence

Rip mew

37
Q

Maps are “curves” applied to what?

A

The shades of gray to accentuate different levels

38
Q

The purpose of maps is to do what?

A

Enhance the visualization of certain aspects of the image

39
Q

In preprocessing it has become apparent that there is a gap present between scan lines in the image, how do we correct for this?

A

Interpolation is used, which averages pixel grey scale values to fill in information where non exists.

40
Q

What does Interpolation do in terms of appearance of pre- processing?

A

Improve the appearance but the trade off is “what is real”

41
Q

Too much interpolation could do what?

A

Misrepresent the image

42
Q

What is edge enhancement?

A
  1. Another tool to improve the look of the image
  2. It will sharpen the boundaries to make them more distinguishable and help make measurements more precise
43
Q

What is a “kernel”?

A

Applied to the pixels to sharpen the boundaries to make them look more distinguishable

44
Q

What is write zoom?

A

Expands the image before storage in the memory

45
Q

What is the benefit of Write zoom for the sonographer?

A

The region of interest is adjustable by sonographer

46
Q

What is ROI (region of interest)?

A

The box that occurs when we press zoom

47
Q

What is the advantage of ROI?

A

Is that the ROI is rescanned and additional scan lines are added which increases spatial resolution, detailed and pixel ratio

48
Q

What is persistence?

A

Takes data from several ultrasound frames and averages them before displaying the image to improve the signal to noise ratio

49
Q

What is persistence also known as?

A

Frame average

50
Q

What is the biggest negative portion of persistence?

A

Frame rate drops

51
Q

Over use or “sampling” over time will decrease what?

A

The temporal resolution so the rate of movement must be small otherwise blurring occurs.

52
Q

Because of the decrease of temporal resolution, persistence is not used for what?

A
  1. Echo
  2. Obstetrics
53
Q

What is post processing?

A

An processing that occurs after the information has been stored into memory

54
Q

Some examples of post processing include what?

A
  1. Measuring
  2. Annotations
  3. Post- processing curves
  4. Read zoom
  5. Color doppler mapping
  6. Angle correction
  7. B-Color (coloured 2-D)

crab map

55
Q

What is the post processing curves function?

A

Curves can be applied to a frozen image and is the assignment of the display intensity (brightness) to a digital value

56
Q

What is an example of an operator controlled function that is accomplished in the DAC?

A

Curves that are applied to a frozen image and is the assignment of display intensity

57
Q

In terms of curves, how does each model vary?

A

Vary by the manufacturer

58
Q

What is the most commonly used probe for Curves?

A

Linear curve

59
Q

What is read zoom?

A

Post processing function that magnifies a frozen image by reassigning the pixel size.

60
Q

What is an disadvantage of read zoom?

A

There is a decrease in resolution

61
Q

What is the B colour function?

A

Uses various colour schemes from oranges to purples to blues.

62
Q

Why would we use B colour?

A

It may help improve the contrast resolution of the image

63
Q

What is the DAC (digital analog converter)?

A

The function that reconverts the digital information into voltage signal

64
Q

Label the image

A
65
Q

Label the image

A
66
Q

Label the basic instrumentation pathway

A
67
Q

Label the beam former pathway

A
68
Q

Label the beam former pathway

A
69
Q

Label the image processing pathway

A

Phys 254 (19 decks)

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