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LMC Ultrasound > Physics Test Ch. 14 and 15 > Flashcards

Physics Test Ch. 14 and 15 Flashcards

1
Q

Which component of an Ultrasound system is responsible for organization and time?

A

Master synchronizer Pg 216

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2
Q

Which component of an Ultrasound system creates an electrical signal that excites the PZT?

A

Pulser Pg 217

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3
Q

The anatomy area of the TGC curve where attenuation occurs

A

Slope

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4
Q

What part creates the firing pattern for a phased array system?

A

Beam Former Pg 221

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5
Q

What are all of the receiver functions?

A
  1. Amplification
  2. Compensation
  3. Compression
  4. Demodulation
  5. Reject Pg 223
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6
Q

Acoustic power of a sound beam is determined by what part of a pulser?

A

Voltage Pg 237

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7
Q

What type of pulser generates constant electrical signal in the form of a sine wave?

A

Continuous wave Pg 236

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8
Q

What is the function that will improve signal to noise?

A

increasing output power is the most common way to improve signal to noise pg 219

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9
Q

What is the receiver function that has to do with demodulization?

A

Rectification Or Smoothing Pg 232

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10
Q

What is the receiver function that keeps ______ within range of the human eye?

A

Compression Gray scale Pg 230

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11
Q

What is the receiver function that is not adjustable by the sonographer?

A

Demodulation Pg 232

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12
Q

When an image is too dark or too bright, what are your two options to adjust the image?

A

output power (if image is too bright) and receiver gain (if image is too dark)

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13
Q

Which receiver function treats signals differently depending on depth?

A

Compensation Pg 226

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14
Q

What is the receiver function that affects the weak signals, leaving the strong signals unchanged?

A

Reject Pg 233

Also known as suppression and threshold

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15
Q

When PRP is long, PRF will be? And how does this affect listening?

A

-Lower
-Longer listening time
Pg 220 (deep imaging)

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16
Q

Know all six components of an ultrasound system

A
  • Transducer
  • Pulser and beam former
  • Receiver
  • Display
  • Storage
  • Master synchronizer Pg 216
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17
Q

What should you do if an ultrasound system displays reflectors only in the far region?

A

Adjust the systems compensation pg 238

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18
Q

What is the best choice if the entire image is too bright?

A

Decrease the output power pg 238

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19
Q

Which component will affect strength of every pulse transmitted into the body?

A

Amplification Pg 224

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20
Q

What are some disadvantages of analog scan converters?

A
  • image fade
  • image flicker
  • instability
  • deterioration pg 243
21
Q

Which electronic component is required for gray scale imaging?

A

Scan converter

22
Q

Read magnification

A

Occurs after the image data is stored in the scan converter; displaying original data.
Number of pixels in the image stay the same which makes the pixels larger when zoomed in p250

23
Q

Temporal resolution may be improved if the region of interest is _____ in comparison to the original?

A

If the bottom of the region of interest is shallower that the original image’s depth of view pg. 252

24
Q

Advantages of an analog scan converter

A

Unlimited and continuous range of values
Real world-numbers that are found in our everyday lives
Spatial resolution is improved because of the large number of storage elements

25
Q

How many shades of gray are represented by 5 bits

A

32

22222=32

26
Q

How many bits are needed to store certain amount of shades of gray.
Example: 10 shades of gray? 11 shades of gray? 15 shades of gray?

A

Four bits are required to store from 9 to 16 shades of gray

27
Q

What are the preprocessing functions?

A

All the changes made to an image before storage.

  • time gain compensation
  • log compression
  • write magnification
  • persistence
  • spatial compounding
  • edge enhancement
  • fill in interpolation pg 249
28
Q

Know about pixels

A 
Smallest building block of a digital picture; number of picture elements per inch 
-Low pixel density: 
     few pixels/inch
     larger pixels
     less detailed image
     lower spatial resolution 
-High pixel density: 
     many pixels/inch
     smaller pixels
     more detailed image
     higher spatial resolution pg. 244
29
Q

Know the diagram on pg. 247 about digital and analog

A

analog——->analog-to-digital converter ——-> digital memory (zeros and ones) ——-> digital-to-analog converter ——–> analog pg. 247

30
Q

Bistable imaging

A

Images are composed of black and white shades only. pg 239

31
Q

Spatial resolution of the CRT is determined by what? (Beth said “CRT” means “screen/monitor”)

A

Pixel density Pg. 377

32
Q

What function is related to the ability for us to see shades of gray?

A

Compression pg 230

33
Q

Real world vs. computer world

A

real world is analog and computer world is digital 242

34
Q

While scanning, you increase your overall gain. Is this preprocessing or postprocessing?

A

Preprocessing pg. 249

35
Q

Preprocessing

A

The manipulation of image data before storage in the scan converter; sonographer controls this; alters image data forever and cannot be reversed/undone pg. 249

36
Q

Postprocessing

A

The manipulation of image data after storage in the scan converter; sonographer controls this; since this occurs after A-to-D conversion and storage, all changes can be reversed; any alterations to a frozen image must be postprocessing

  • Any change after freeze frame
  • Black/white inversion
  • Read magnification
  • Contrast variation
  • 3-D rendering pg. 249
37
Q

What portion converts data into numbers?

A

Digital scan converter Pg. 243

38
Q

What are the advantages of coded excitation?

A
  • Higher signal-to-noise ratio
  • Improved axial resolution
  • Improved spatial resolution
  • Improved contrast resolution
  • Deeper penetration pg. 253
39
Q

What is fill-in interpolation?

A

Fill in the gaps of missing data in a way that cannot be detected by the observer; form of preprocessing pg. 257

40
Q

What is coded excitation? (where does it occur)

A

Creates very long sound pulses containing a wide range of frquencies. Occurs in the pulser. pg. 253

41
Q

What is spatial compounding?

A

Spatial compounding averages multiple frames obtained by steering the sound beam in different directions

42
Q

What is elastography?

A

Produces images from sound reflection. Images are relayed to mechanical properties of tissue. Theory of elastography is that tissue will deform differently following the application of a force. Estimates tissue stiffness. pg 258

43
Q

Which technology reduces speckle and improves spatial resolution?

A

Spatial compounding pg. 254

44
Q

What is speckle?

A

is noise resulting from constructive and destructive interference of small sound wavelets. pg 374

45
Q

Which technology provides a history of past frames that overlay on the present frames?

A

temporal compounding, persistence, or temporal averaging pg 256

46
Q

This type of pulser generates numerous electrical spikes, which ultimately create a single sound pulse

A

Pulsed wave, phased array p 237

47
Q

Demodulation

A
  • fourth function of the receiver
  • is a two-part process that changes the electrical signals within the receiver into a form more suitable for display on a monitor
48
Q

when determining receiver gain or output power which should be in the main concern

A

ALARA/bioeffects

49
Q

The signal from the transducer to the receiver is what?

A

~

LMC Ultrasound (32 decks)

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