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Spring: Physics > Chapter 12/13 Q&A: test 1 > Flashcards

Chapter 12/13 Q&A: test 1 Flashcards

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1
Q

Mechanical scanning produces pictures that are similar in shape to linear phased array images

A

True

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2
Q

Many active elements fire at almost the same time in a mechanical scanner

A

False

There is only one active element in a mechanical scanner

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3
Q

Many active elements fire at almost the same time in a phased array scanner

A

True

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4
Q

Which transducer is best described as mechanically steered and fixed, single focus?

A

mechanical

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5
Q

Which transducer is best described as mechanically steered and multi-focus?

A

Annular phased array

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6
Q

Which transducer creates a rectangular shaped image?

A

linear sequential array

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7
Q

A linear phased array transducer has 128 crystals. How many of these crystals are fired to create a single sound beam?

A

128

With linear phased array transducers, all the active elements are fired

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8
Q

A linear sequential array transducer has 128 crystals. How many of these crystals are fired to create a single sound beam?

A

a small group

With linear sequential array transducers, a small group of active elements are fired

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9
Q

In a linear phased array, what is the firing pattern that steers a beam to the left or right?

A

The firing pattern that steers a beam to the left or right is electronic slope

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10
Q

In linear phased arrays, what is the firing pattern that focuses a sound beam?

A

The firing pattern that focuses a sound beam is electronic curvature

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11
Q

There are large time delays in the firing pattern of a linear phased array transducer

A

False

there are tiny time delays

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12
Q

A machine that displays A-mode and two-dimensional images is called a duplex scanner

A

False

a machine that displays Doppler and 2D images is a duplex scanner

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13
Q

Which transducer improves elevational resolution?

A

1 1/2 dimensional array

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14
Q

Side lobes degrade axial resolution

A

False

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15
Q

Side lobes degrade lateral resolution

A

True

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16
Q

Which form of resolution improves when frame rate increases?

A

temporal resolution

temporal resolution is directly related to frame rate

higher frame rates improve temporal resolution

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17
Q

What is consistent with improved temporal resolution?

A

higher frame rate

Frame rate determines temporal resolution

Higher frame rates(lower Tframe) result in improved temporal resolution

18
Q

What decreases temporal resolution?

A

lower frame rate

deeper imaging

multi-focus

19
Q

A sonographer adjusts an ultrasound scan to double the depth of view from 5cm to 10cm.

What happens to the frame rate?

A

the frame rate is halved

frame rate and imaging depth are inversely related

20
Q

A sonographer adjusts an ultrasound scan to double the depth of view from 5cm to 10cm.

If the frame rate remains the same, what will also occur?

A

narrower sector

21
Q

A sonographer adjusts an ultrasound machine to change the sector size from 90 to 45 degrees. Nothing else changes. What happens to the frame rate?

A

the frame rate is doubled

22
Q

A sonographer adjusts an ultrasound system to change the sector size from 90 to 45 degrees. The frame rate was unchanged. What else must have happened?

A

line density was doubled

23
Q

A sonographer, using a phased array ultrasound system, turns off the multi-focus feature. What is the most likely consequence of this action?

A

temporal resolution improves

24
Q

A sonographer increases the line density from 1 line per degree of sector to 3 lines per degree of sector. What is the most likely consequence of this action?

A

temporal resolution decreases

25
Q

A sonographer reduces the sector angle from 90 degrees to 30 degrees. At the same time, the ultrasound system automatically increases the line density from 1 line per degree to 2 lines per degree. No other changes are made. What will happen to the frame rate?

A

frame rate increases

26
Q

A sonographer reduces the sector angle from 90 degrees to 30 degrees. At the same time, the ultrasound system automatically increases the line density from 1 line per degree to 3 lines per degree. No other changes are made. What will happen to temporal resolution?

A

temporal resolution is unchanged

27
Q

What is most important in determining the frame rate of a system?

A

speed of sound in a medium

28
Q

What is most important in determining the frame rate of a system?

A

depth of view

29
Q

What is the frame rate if each image of the ultrasound system is created in 0.02sec (1/50sec)?

A

50Hz

frame rate and Tframe are reciprocals

30
Q

What is the time needed to make a single image if the frame rate of an ultrasound system is 20Hz?

A

0.05s (1/20)

frame rate and Tframe are reciprocals

31
Q

The critical factor in determining frame rate, line density, and imaging depth is the transducer style

A

false

its time

32
Q

The number of lines per frame and the frame rate determine the frequency.

A

false

it determines PRF

33
Q

The number of lines per frame and the frame rate determine the PRF.

A

true

34
Q

If the imaging depth of a scan is 15cm and there are 100 lines in the image, then the number of pulses making up the scan is 1500.

A

false

number of pulses would be 100

35
Q

If the imaging depth of a scan is 15cm and there are 100 lines in the image, then the number of pulses making up the scan is 100.

A

true

36
Q

If 100 scan lines make up an image and the frame rate is 30 per second, then the transducer’s frequency is 3,000Hz.

A

false

a transducer’s frequency is independent of the characteristics of the image that it creates.

37
Q

If 100 scan lines make up an image and the frame rate is 30 per second, then the system’s pulse repetition frequency is 3,000Hz.

A

true

PRF is the number of pulses created per second. It is lines per image multiplied by frame rate.

38
Q

When the frame rate is 30Hz, how long does it take to create a frame?

A

1/30 sec

frame rate and Tframe are reciprocals

39
Q

Under certain conditions, an ultrasound system creates each image in 0.01 seconds. What is the frame rate?

A

100Hz

frame rate and Tframe are reciprocals

40
Q

What is the fundamental limitation of temporal resolution?

A

speed of sound in the medium

Spring: Physics (10 decks)

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