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Sonography > Ch. 14 Physics: Pulse Echo Instrumentation > Flashcards

Ch. 14 Physics: Pulse Echo Instrumentation Flashcards

1
Q

What are the 2 major functions of the US machine?

A

creation of the sound beam

processing the received signals into diagnostic information.

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2
Q

What are the 6 components of the US system?

A

Transducer

Pulser and beam former

Receiver

Display

Storage

Master synchronizer

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3
Q

What does the transducer do during transmission?

A

transforms electrical energy into acoustic energy.

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4
Q

What does the transducer do during reception?

A

converts returning acoustic energy into electrical energy.

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5
Q

Creates electrical voltages that excite the transducer’s PZT to produce sound beams

A

Pulser

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6
Q

When does the pulser function?

A

During transmission

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7
Q

What determines the amplitude, PRP, PRF?

A

Pulser

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8
Q

What are the ranges for the Transducer Output?

A

0 to 100 volts

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9
Q

What controls the overall brightness of the reflected echoes?

A

Output

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10
Q

If the pulser is set low, will the image be dark or bright?

A

Dark

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11
Q

If the pulser is set high, will the image be dark or bright?

A

bright

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12
Q

What are the synonyms for pulse voltage?

A

Output gain, acoustic power, transmitter output, power, or gain

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13
Q

True or false:
Output gain/Transducer output is controlled by the sonographer

A

True

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14
Q

Transducer Output is standardized by what two mathematical calculations?

A

Thermal index (TI)

Mechanical Index (MI)

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15
Q

True or false:
Thermal index (TI) and Mechanical Index (MI) help determine bioeffects.

A

True

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16
Q

_________ voltages increase the likelihood of thermal heating or bioeffects to occur.

A

Higher

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17
Q

_______ voltages are most desired, when overall image quality is still optimal.

A

Lower

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18
Q

Decreased energy =

A

less bioeffects

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19
Q

a disturbance that degrades image quality by interfering with the clarity of a signal.

A

Noise

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20
Q

A comparison of the meaningful information in an image, compared to the amount of contamination present.

A

Signal-to-noise ratio

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21
Q

Meaningful information =

A

signal

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22
Q

Contamination =

A

noise

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23
Q

High ratio =

A

high quality/high signal

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24
Q

Low ratio =

A

low quality/low signal, high noise presence resulting in a less diagnostic image

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25
Q

Increasing power output will ________ the signal-to-noise ratio

A

increase

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26
Q

In addition to the transmission output, the pulser also determines the __________ of the voltage being given

A

timing

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27
Q

Longer delays means

A

longer pulses (long PRP)

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28
Q

Shorter delays means

A

shorter pulses (short PRP)

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29
Q

PRP is affected by what?

A

depth

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30
Q

A short PRP means ______ PRF

A

high

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31
Q

A long PRP means _______ PRF

A

low

32
Q

creates and distributes the delay pattern for array transducers.

A

Beam former

33
Q

What happens to the beam former during transmission?

A

Coordinates the signals sent to each active element to optimize the transmitted beams

Adjusts the electrical spike voltages to reduce lobe artifacts (apodization)

34
Q

What happens to the beam former during reception?

A

Establishes the time delays used for dynamic receive focusing

Controls dynamic aperture by varying the # of crystals used during transmission and reception

35
Q

What Protects sensitive components from the high voltage transmit signals in the beam former?

A

the switch

36
Q

What Directs electrical signals from the transducer to the appropriate electronic and processing components in the beam former?

A

The switch

37
Q

What is made up of A single PZT element in the transducer, The electronics in the beam former/pulser, and The wire that connects them all?

A

The channel

38
Q

The number of elements that can be excited simultaneously is determined by

A

The number of channels

39
Q

How many channels do most systems have?

A

32-256

40
Q

What prepares the information in the received signals for display on the system’s monitor?

A

The receiver

41
Q

The 5 receiver operations must be performed in this order:
(conveniently in alphabetical order)

A

Amplification

Compensation

Compression

Demodulation

Reject

42
Q

contains the pieces that create, carry, and transmit the voltage into a signal

A

the channel

43
Q

processes the electric signals returned from the transducer and prepares the information for display.

A

The receiver

44
Q

the first process performed by the receiver upon reception of reflected signals

A

Amplification

45
Q

All returning signals undergo …..

A

amplification

46
Q

True or false:
Amplification cannot distinguish between signal and noise; it increases both identically.

A

True

47
Q

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

A

True

48
Q

the second function performed by the receiver

A

Compensation

49
Q

True or false :
The sonographer can adjust compensation with a series of slider bars

A

True

50
Q

What are the synonyms for compensation?

A

Time Gain Compensation (TGC)

Depth Gain Compensation (DGC)

Swept Gain

51
Q

Sound waves weaken the deeper they travel producing progressively dark images. _______________ counteracts this natural occurrence, by creating uniform brightness at ALL depths.

A

Compensation

52
Q

What controls allow the Sonographer to make the appropriate adjustments to compensate for the loss of gain as the image depth increases, and signal strength decreases?

A

TGC -Time Gain Compensation

53
Q

the third function of the receiver

A

compression

54
Q

What decreases the dynamic range of a signal?

A

compression

55
Q

Compression is also known as …..

A

log compression or dynamic range

56
Q

Compression is reported in what?

A

dB

57
Q

True or false:
Compression increases the contrast resolution of only part of the image

A

False
entire image

58
Q

the fourth function of the receiver

A

Demodulation

59
Q

What are the two-part process that changes the electrical signals within the receiver into a form suitable for display on a monitor?

A

Rectification

Smoothing

60
Q

Can the sonographer adjust demodulation?

A

no, it is not adjustable

61
Q

What is the purpose of demodulation?

A

to change the form of the electrical signal, but has no visible effect on the image

62
Q

AKA Threshold or Suppression

A

reject

63
Q

allows the sonographer to control whether low-level gray scale information will appear on the image, reducing electronic noise

A

reject or threshold

64
Q

By increasing the threshold, you _______ the appearance of weak echo signals

A

decrease

65
Q

What are the two levels of reject in the ultrasound system?

A

One that is built into the system

And the other is user adjustable

66
Q

What are the 5 functions of the reciever?

A

Amplification of both pulses

Compensation for weaker pulses

The difference between the pulse amplitudes are reduced

The pulses are converted to another form

The weaker pulses are removed

67
Q

Are Output Power and Receiver Gain adjustable by the sonographer?

A

yes

68
Q

When is output power adjusted?

A

during transmission

69
Q

when is receiver gain adjusted?

A

during reception

70
Q

What Affects image brightness by altering the strength of the sound being transmitted into the body and Improves signal-to-noise ratio?

A

output power

71
Q

What Alters the strength of the voltage received in the transducer during reception and Signal-to-noise ratio remains unchanged ?

A

Receiver gain

72
Q

Which exposes the patient to bioeffects? output power or receiver gain?

A

output power

73
Q

What is ALARA?

A

As

Low

As

Reasonably

Achievable

74
Q

when should the principle known as ALARA be used?

A

when making power output changes

75
Q

To correct an extremely bright image, what adjustment would you make first?

Decrease Receiver Gain?

Decrease Output Power?

A

Decrease Output Power

76
Q

To correct an extremely dark image, what adjustment would you make first?

Increase Receiver Gain?

Increase Output Power?

A

Increase Receiver Gain

Sonography (39 decks)

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