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Intro > Ch. 14 Pulsed Echo Instrumentation > Flashcards

Ch. 14 Pulsed Echo Instrumentation Flashcards

1
Q

Pulsed Echo ultrasound system has two major functions:

A
  1. The preparation and transmission of electrical signals to the transducer, which creates the sound beam.
  2. The reception of electrical signals from the transducer, with subsequent processing into clinically meaningful images and sounds.
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2
Q

The _____________ and _________________ of electrical signals to the transducer, which creates the sound beam.

A

The Preparation and transmission of electrical signals to the transducer, which creates the sound beam.

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3
Q

The ___________________________ of electrical signals from the transducer, with subsequent processing into clinically meaningful images and sounds.

A

The Reception of electrical signals from the transducer, with subsequent processing into clinically meaningful images and sounds

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4
Q

ultrasound systems contain these six major components:

A
  1. transducer
  2. pulser and beam former
  3. reciever
  4. display
  5. storage
  6. master synchronizer
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5
Q

_____________________: during transmission, this transforms electrical energy into acoustic energy. During reception, it converts the returning acoustic energy into electrical energy.

A

Transducer : during transmission, this transforms electrical energy into acoustic energy. During reception, it converts the returning acoustic energy into electrical energy.

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6
Q

_______________ and ______________________: creates and controls the electrical signals sent to the transducer that generate sound pulses. The ______________________ determines the amplitude, pulse repetition period, and pulse repetition frequency. While the _________________________ determines the firing delay patterns for phased array systems.

A

Pulser and Beam Former : creates and controls the electrical signals sent to the transducer that generate sound pulses. The Pulser determines the amplitude, pulse repetition period, and pulse repetition frequency. While the Beam Former determines the firing delay patterns for phased array systems.

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7
Q

____________________________ : transforms the electrical signals from the transducer (produced by the reflected signal) into a form suitable for display.

A

Reciever : transforms the electrical signals from the transducer (produced by the reflected signal) into a form suitable for display.

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8
Q

______________________ : presents processed data. This may be a flat screen monitor, a transparency, a spectral plot, or a variety of other formats.

A

Display : presents processed data. The display may be a flat screen monitor, a transparency, a spectral plot, or a variety of other formats.

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9
Q

_____________________ : archives the ultrasound studies. Typically these devices (or media) include computer hard drives, CD, DVD, videotape, magneto-optical discs, paper printouts, photographs, and USB drives.

A

Storage : archives the ultrasound studies. Typically these devices (or media) include computer hard drives, CD, DVD, videotape, magneto-optical discs, paper printouts, photographs, and USB drives.

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10
Q

_________________________________ : maintains and organizes the proper timing and interaction of the system’s components.

A

Master Synchronizer : maintains and organizes the proper timing and interaction of the system’s components.

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11
Q

The ____________ creates electrical signals that excite the transducer’s PZT crystals and create sound beams

A

The Pulser creates electrical signals that excite the transducer’s PZT crystals and create sound beams

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12
Q

The pulser functions during ________________________

A

The pulser functions during transmission

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13
Q

True or False: Changes in pulser voltage modify the brightness of the entire image displayed on the systems screen

A

True

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14
Q

Changes in the pulser voltage modify the ______ of the image.

higher voltage (output) = _______________ image

lower voltage (output) = ______________ image

A

Changes in the pulser voltage modify the brightness of the image

higher voltage (output) = brighter image

lower voltage (output) = darker image

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15
Q

When the pulser voltage is low, the active element vibrates (more,less) forcefully, transmits (stronger,weaker) sound beams into the body, reflected echoes are (stronger, weaker) and the entire image is (brighter, darker)

A

less; weaker; weaker; darker

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16
Q

When the pulser voltage is high, the active element vibrates (more, less) forcefully, transmits (stronger, weaker) sound beams into the body, reflected echoes are (stronger, weaker) and the entire image is (brighter, darker)

A

more; stronger; stronger; brighter

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17
Q

output gain, acoustic power, pulser power, energy output, transmitter output are also known as for …

A

Pulser voltage

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18
Q

Can transducer output be adjusted by the sonographer?

A

Yes

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19
Q

As long as image quality is optimal, (lower, higher) pulser voltage is desirable

A

lower

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20
Q

__________________ is loosely defined as a random and persistent disturbance that obscures or reduces a signals clarity.

A

Noise is loosely defined as a random and persistent disturbance that obscures or reduces a signals clarity

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21
Q

A comparison of the meaningful information (signal) in an image, compared to the amount of contamination (noise)

A

Signal to Noise ratio

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22
Q

When the signal-to-noise ratio is ____________, the signal is much stronger than the noise and the image is of high quality.

A

When the signal-to-noise ratio is high, the signal is much stronger than the noise and the image is of high quality.

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23
Q

When the signal-to-noise ratio is ___________, the strength of the signal is closer to the strength of the noise and the image is of less quality.

A

When the signal-to-noise ratio is low, the strength of the signal is closer to the strength of the noise and the image is of less quality.

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24
Q

As the sonographer increases output power, the signal-to-noise ratio _________________. (increases, decreases)

A

increases

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25
Q

increasing output power is the most common way to ___________________ the signal-to-noise ratio

A

increasing output power is the most common way to improve the signal-to-noise ratio

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26
Q

The pulser also determines the time between one voltage spike and the next known as _____________________

A

The pulser also determines the time between one voltage spike and the next known as Pulse repetition period or PRP

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27
Q

If the pulser determines PRP, what else does it determine?

A

PRF (PRF and PRP are reciprocals)

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28
Q

PRP determines the:

A

maximum imaging depth (depth of view)

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29
Q

When the PRP is short, the PRF is __________ and the system spends (more,less) time listening?

A

When the PRP is short, the PRF is high and the system spends less time listening

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30
Q

When the PRP is long, the PRF is _____________ and the system spends (more,less) time listening?

A

When the PRP is long, the PRF is low and the system spends more time listening

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31
Q

Can a sonographer change the depth of view?

A

yes

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32
Q

Shallow imaging = __________ listening, _____________ PRP, ______________ PRF and _________________ duty factor

A

Shallow imaging =

less listening

shorter PRP

higher PRF

higher duty factor

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33
Q

Deep imaging = ___________ listening, _____________ PRP, _______________ PRF, ________________ duty factor

A

Deep imaging =

more listening

longer PRP

lower PRF

lower duty factor

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34
Q

The __________________________ functions with array transducers during transmission and reception

A

The Beam Former functions with array transducers during transmission and reception

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35
Q

The beam former also adjusts electrical spike voltages to reduce lobe artifacts in a process called …

A

The beam former also adjusts electrical spike voltages to reduce lobe artifacts in a process called Apodization

36
Q

Modern beam formers use advanced microprocessor technology and produce signals in digital format. This device is called ______________________________

A

Digital Beam Former

37
Q

The beam former has a special “transmit-recieve” _____________ that is important during transmission and reception

A

The beam former has a special “transmit-recieve” switch that is important during transmission and reception

38
Q

A ____________________ is made up of a single PZT elements in the transducer, the electronics in the beam former/ pulser, and the wire that connects them

A

A Channel is made up of a single PZT element in the transducer, the electronics in the beam former/ pulser, and the wire that connects them

39
Q

The number of elements in an array transducer that can be excited is determined by the number of ______________________

A

The number of elements in an array transducer that can be excited is determined by the number of channels

40
Q

Most systems have between __ and ___ channels.

A

32-256 channels

41
Q

What are the 5 operations that must be performed in the appropriate order for the system to function properly

A
  1. amplification
  2. compensation
  3. compression
  4. demodulation
  5. reject
42
Q

The first function of the receiver is ________________________, also called …

A

The first function of the receiver is Amplification, also called receiver gain

43
Q

All electrical signals in the receiver gain are affected ________________________ by amplification

A

All electrical signals in the receiver gain are affected identically by amplication

44
Q

True or False: the entire image is made brighter or darker when the sonographer adjusts receiver gain

A

true

45
Q

Amplification (does, does not) improve signal-to-noise ration, since both signal and noise are amplified equally

A

does not

46
Q

True or False: Amplification alone can make an image of uniform brightness from top to bottom

A

false

47
Q

Can a sonographer alter the amplification?

A

yes

48
Q

Amplification is measured with units of ______________, which are _______________ units of measure

A

Amplification is measured with units of decibels, which are relative units of measure

49
Q

Typical values of amplification:

A

60-100 db

50
Q

The process of improving the quality of a signal before it is amplified:

A

preamplification

51
Q

Preamplification occurs ____ to the transducer and often within the transducer itself.

A

Preamplification occurs close to the transducer and often within the transducer itself

52
Q

The second function of the receiver is ___________________________

A

The second function of the receiver is compensation

53
Q

Without compensation, the ultrasound image would become progressively _________________ with increasing depth

A

Without compensation, the ultrasound image would become progressively darker with increasing depth

54
Q

The receiver corrects for attenuation with a process called:

A

compensation

55
Q

Compensation creates an image that is:

A

uniformly bright from top to bottom

56
Q

Can the sonographer adjust compensation?

A

yes

57
Q

Compensation is measure in units of:

A

decibels

58
Q

Compensation treats echoes differently, depending upon:

A

the depth from which they arise

59
Q

Three identical masses located in the body at depths of 2cm, 4cm, and 6cm will produce reflections with different strengths. The echo will be the ________ (strongest,weakest) from the mass of 2cm and the _________ (strongest, weakest) from the mass at 6cm

A

Three identical masses located in the body at depths of 2cm, 4cm, and 6cm will produce reflections with different strengths. The echo will be the strongest from the mass of 2cm and the weakest from the mass at 6cm

60
Q

Time gain compensation (TGC), depth gain compensation (DGC), and swepth gain are all AKA’s for ..

A

Compensation

61
Q

At superficial depths, reflections undergo a small, constant amount of compensation called

A

The near gain

62
Q

The depth at which variable compensation begins is known as _____________

A

The depth at which variable compensation begins is known as delay

63
Q

At the depth of the _______________, reflections are maximally compensated by the ultrasound system

A

At the depth of the knee, reflections are maximally compensated by the ultrasound system

64
Q

The third function of the receiver is ______________________

A

The third function of the receiver is compression

65
Q

The ___________________ indicated the maximum amount of compensation that the receiver can provide

A

The far gain indicated the maximum amount of compensation that the receiver can provide

66
Q

Compression is produced twice. First, compression keeps the electrical signal within the accuracy range of the systems electronics and second, keeps an images ________________________ content within the range of detection by the human eye

A

Compression is produced twice. First, compression keeps the electrical signal within the accuracy range of the systems electronics and second, keeps an images gray scale content

67
Q

Humans can distinguish approximately (20, 30, 40) shades of grey.

A

20

68
Q

In the region of the _________, compensation corrects for the effects of increasing attenuation that result from increasing path length.

A

In the region of the slope, compensation corrects for the effects of increasing attenuation that result from increasing path length

69
Q

What allows us to visualize different tissues within 20 gray shades?

A

Compression

70
Q

Can a sonographer adjust compression?

A

yes

71
Q

Compression is expressed in units of:

A

decibels

72
Q

Log compression where small differences in _____________ signals are displayed and seen as different gray scale levels

A

Log compression where small differences in weak signals are displayed and seen as different gray scale levels

73
Q

Why is log compression important in clinical ultrasound?

A

most meaningful back scattered signals from biological tissues are very weak and sonographer must be able to see differences in the weak signals

74
Q

The fourth function of the receiver is ________________________

A

demodulation

75
Q

Demodulation is a process of

A

converting the voltage delivered to the receiver from one form to another

76
Q

Demodulation is a two-part process:

A
  1. rectification (converts all neg voltages into pos voltages)
  2. smoothing or enveloping (places a smooth line around the “bumps” and evens them out)
77
Q

Is demodulation adjustable by the sonographer?

A

No

78
Q

demodulation effect on image?

A

none; just changes the form of the electrical signal so that it is appropriate for the system’s display

79
Q

The fifth function of the Receiver is:

A

Reject

80
Q

Reject allows the sonographer to control whether ________-level gray scale information within the data will appear on the displayed image
*Rejection does not affect bright echoes

A

Reject allows the sonographer to control whether low-level gray scale information within the data will appear on the displayed image

81
Q

Can Reject be adjusted by the sonographer

A

Yes

82
Q

Reject effect on image:

A

affects low-level signals on the image, regardless of their location

83
Q

What is the difference between output power and receiver gain?

A

Output power affects image brightness by altering the strength of the sound pulse that the transducer sends to the body - increasing output power improved the signal-to-noise ratio

receiver gain (amplification) alters the strength of the voltages in the receiver that the transducer created during the reception

84
Q

Patient exposure to ultrasound is affected by:

A

alterations in output power but not not by changed in amplification

85
Q

ALARA Principle (As Low As Reasonably Achievable)

A

Radiographic principle that dictates the use of every method available to reduce radiation exposure to the patient in order to minimize risks and adverse consequences of ionizing radiation

86
Q

According to the ALARA principle, if the image is too dark increase the (receiver gain, output power) first.

A

receiver gain

87
Q

According to the ALARA principle, if the image is too bright decrease the (receiver gain, output power)

A

output power

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