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Ultrasound Physics Review > Displays > Flashcards

Displays Flashcards

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1
Q

A video display that is limited to black and white only, with no shades of gray, is called _____.

a. binary
b. bistable
c. monochrome
d. inchworm

A

b. binary

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2
Q

What is the approximate number of frames that must be presented each second for the human eye to perceive the display without flickering?

a. 2
b. 30
c. 100
d. 500

A

b. 30

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3
Q

What was the original purpose for the ultrasound system’s analog scan converter?

a. to increase the dynamic range of ultrasound systems
b. to make real-time imaging possible
c. to increase the sensitivity of ultrasound systems
d. to allow for gray scale imaging

A

d. to allow for gray scale imaging

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4
Q

Which of the following is best described as an analog number?

a. the weight of a person
b. the number of people in a room
c. the number of stars in the sky
d. the number of tires on a car

A

a. the weight of a person

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5
Q

True or False?

A digital representation of a number can achieve only specific fixed values.

A

True

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6
Q

True or False?

Digital scan converters do not use computer technology to process electronic data into images.

A

False

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7
Q

Two digital scan converters are undergoing evaluation. Both produce images of the same size. System A has 1,000,000 pixels, with 10 bits assigned to each. System B has 250,000 pixels, with 12 bits assigned to each. Which system is more likely to have the capability to display very small details in an image?

a. System A
b. System B
c. both are the same
d. cannot be determined

A

a. System A

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8
Q

What happens to a digital image when the pixel density increases?

a. spatial detail improves
b. temporal resolution increases
c. the field of view expands
d. there are more shades of gray

A

a. spatial detail improves

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9
Q

Two digital scan converters are undergoing evaluation. System A has 1,000,000 pixels and the picture size is 100 square inches. System B has an image size of 10 square inches composed of 250,000 pixels. Which image is more likely to display very small details?

a. System A
b. System B
c. both are the same
d. cannot be determined

A

b. System B

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10
Q

What is the smallest part of a digital picture?

a. bit
b. byte
c. pixel
d. fractel

A

c. pixel

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11
Q

True or False?

The greater the number of bits assigned to each pixel of a digital image, the greater the number of shades of gray the image has.

A

True

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12
Q

What is the smallest amount of digital storage called?

a. bit
b. byte
c. pixel
d. fractel

A

a. bit

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13
Q

Which of these is a binary number?

a. 12211221
b. 10000000
c. 98765432
d. 01010102

A

b. 10000000

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14
Q

Two digital scan converters are undergoing evaluation. System A has 1,000,000 pixels, with 4 bits assigned to each. System B has 250,000 pixels, with 12 bits assigned to each. Which system is more likely to display images with very subtle differences in grayscale?

a. System A
b. System B
c. both are the same
d. cannot be determined

A

b. System B

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15
Q

A byte is composed of _____ bits. A word is composed of _____ bytes.

a. 2, 2
b. 8, 2
c. 16, 16
d. 8, 16

A

b. 8, 2

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16
Q

True or False?

The greater the number of bits assigned to each pixel of a digital image, the greater the spatial resolution of the image is.

A

False

17
Q

What happens to an image when the number of bits allocated to each pixel increases?

a. spatial detail improves
b. frame rate increases
c. field of view expands
d. more shades of gray

A

d. more shades of gray

18
Q

What is the maximum number of shades of gray that are represented with 4 bits.

a. 4
b. 8
c. 12
d. 16

A

d. 16

19
Q

With 6 bits, what is the largest number of different gray shades that can be stored?

a. 8
b. 16
c. 64
d. 256

A

c. 64

20
Q

How many bits are required to display 10 different shades of gray? 14 shades? 15 shades?

a. 4 bits, 5 bits, 6 bits
b. 10 bits, 14 bits, 15 bits
c. 4 bits, 4 bits, 2 bits
d. 4 bits, 4 bits, 4 bits

A

d. 4 bits, 4 bits, 4 bits

21
Q

What is the number of binary digits required to store 29 levels of gray?

a. 4
b. 5
c. 6
d. 29

A

b. 5

22
Q

True or False?

For digital image information to be displayed on a conventional television screen, the data must be processed by a digital-to-analog converter.

A

True

23
Q

True or False?

Preprocessing of image data occurs after the data has been stored in the scan converter.

A

False

24
Q

True or False?

Postprocessing of image data occurs after the data has been stored in the scan converter.

A

True

25
Q

All of the following are true of read zoom except:

a. preprocessing function of a receiver
b. same number of pixels are in the original ROI and the zoomed image
c. on the screen, the pixels in the zoomed image are larger than those in the ROI
d. the same number of ultrasound pulses are used to create the original ROI and the zoomed image

A

a. preprocessing function of a receiver

26
Q

All of the following are true of write zoom except:

a. preprocessing function of the receiver
b. the same number of pixels are in the original ROI and the zoomed image
c. the pixel size in the zoomed image and the ROI are the same
d. in comparison to the zoomed image, fewer ultrasound pulses are used to create the original ROI

A

b. the same number of pixels are in the original ROI and the zoomed image

27
Q

True or False?

The assignment of different shades of gray to the digital numbers stored in the scan converter acts to improve the diagnostic value of an ultrasound exam.

A

True

28
Q

The relationship between the largest and the smallest signal amplitudes processed by a component of an ultrasound system is called the _____ and has units of _____.

a. decibels, watts
b. intensity, W/cm^2
c. dynamic range, dB
d. proportionality, dB

A

c. dynamic range, dB

29
Q

Which of these components typically has the greatest dynamic range?

a. display
b. pulser
c. amplifier
d. demodulator

A

c. amplifier

30
Q

Which of the following components typically has the lowest dynamic range?

a. display
b. pulser
c. amplifier
d. demodulator

A

a. display

31
Q

Why is it necessary for the receiver to perform compression on the electrical signals that it processes?

a. the dynamic range of the system’s electronics is less than the dynamic range of the received sound reflection
b. the display’s dynamic range exceeds the transducer’s dynamic range
c. the dynamic range of the receiver is less than the dynamic range of the image processor
d. the dynamic range of the display exceeds the dynamic range of all other components of the ultrasound system

A

a. the dynamic range of the system’s electronics is less than the dynamic range of the received sound reflection

32
Q

A signal with 120 dB dynamic range is compressed by 40 dB. What is the dynamic range of the compressed signal?

a. 40 dB
b. 120 dB
c. 3 dB
d. 80 dB

A

d. 80 dB

33
Q

A signal with a 120 dB dynamic range was previously by 40 dB. What is the dynamic range of the original uncompressed signal?

a. 160 dB
b. 120 dB
c. 3 dB
d. 80 dB

A

a. 160 dB

34
Q

Which display is limited to a single pair of brightness or display levels?

a. CRT
b. binary
c. bistable
d. gray scale

A

c. bistable

35
Q

All of the following are consistent with an image containing black and white only with no shades of gray except:

a. bistable
b. high contrast
c. wide dynamic range

A

c. wide dynamic range

36
Q

Which of the following terms is not associated with a wide dynamic range image?

a. low contrast
b. many shades of gray
c. bistable

A

c. bistable

Ultrasound Physics Review (30 decks)

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