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Ultrasound Physics > Finals > Flashcards

Finals Flashcards

1
Q

Sound waves are:
a. electric
b. mechanical, transverse
c. spectral
d. longitudinal, mechanical

A

longitudinal, mechanical

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2
Q

The speed of US in soft tissue is closest to:
a. 1,540 km/sec
b. 1.54 km/msec
c. 1,500m/s
d. 1,540mm/sec

A

c. 1,500m/s

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3
Q

The frequency closest to the lower limit of US is:
a. 19,000kHz
b. 10,000MHz
c. 20,000 msec
d. 15,000Hz

A

d. 15,000Hz

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4
Q

Which is not an acoustic variable?
a. density
b. pressure
c. distance
d. intensity

A

d. intensity

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5
Q

The effects of soft tissue on US are called:
a. acoustic proliferation
properties
b. dynamic effects
c. acoustic propagation properties
d. biologic effects

A

c. acoustic propagation properties

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6
Q

Al of the following are true EXCEPT:
a. Two waves with identical frequencies must interfere constructively.
b. Constructive interference is associated with waves that are in-phase.
c. Out-of-phase waves interfere destructively
d. Waves of different frequencies may exhibit both constructive and destructive interference at different times.

A

a. Two waves with identical frequencies must interfere constructively.

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7
Q

Put in decreasing order:
a. deca
b. deci
c. micro
d. centi

A

Deca, deci, centi,micro

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8
Q

—–is the time to complete one cycle.
a. pulse duration
b. pulse period
c. period
d. duration period

A

c. period

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9
Q

Which of the
following sound waves is ultrasonic and least useful in diagnostic imaging?
a. 30 KHz
b. 8 MHZ
c. 8,000 Hz
d. 3,000 kHz
e. 15 Hz

A

a. 30 KHz

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10
Q

What is the frequency of a wave with 1 msec period?
a. 10,000 Hz
b.1000 KHz
c. 1 KHz
d. 1 MKz

A

c. 1 KHz

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11
Q

is the distance covered by one cycle.
a. pulse length
b. wavelength
c. cycle distance
d. cycle duration

A

b. wavelength

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12
Q

Which of the following is determined by the source and the medium?
a. frequency
b. period
c. propagation speed
d. range resolution

A

d. range resolution

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13
Q

Propagation speed = wavelength
a. pulse duration
b. period
e. number of cycles in the puls e
d. frequency

A

d. frequency

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14
Q

As a result of the
propagation speed increases.
a. increasing stiffness and increasing density
b. increasing stiffness and increasing elasticity
c. decreasing compressibility and decreasing den
sity
d. decreasing stiffness and decreasing density

A

c. decreasing compressibility and decreasing density

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15
Q

Put in decreasing order of propagation speed.
a. gas
b. liquid
c. solid

A

Solid, liquid, gas

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16
Q

If the frequency of US is increased from 0.77MHz to 1.54MHz, what happens to the wavelength?
a. doubles
b. halved
c. remains the same
d. 4 times greater

A

b. halved

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17
Q

A sound waves’ frequency is 10 MHz. The wave is traveling in soft tissue. What is its wavelength?

a. 0.15 mm
b. 1.54mm
c. 15.4mm
d. 0.77 mm
e. 10 MHz

A

a. 0.15 mm

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18
Q

If the frequency of an US wave
is doubled, what happens to the period?
a. doubles
b. halved
c. remains the same
d. 4 times greater

A

b. halved

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19
Q

If the frequency of US is increased from 0.77MHz to 1.54MHz, what happens to the propagation speed?

a. doubles
b. halved
c. remains the s a m e
d. 4times

A

c. remains the s a m e

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20
Q

The units of pulse repetition frequency are

a. per minute
b. msec
c. mm/us
d. MHx

A

b. msec

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21
Q

The time from the beginning of a pulse until its end is
a. period
b. pulse duration
c. puise length
d. PRF

A

b. pulse duration

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22
Q

What happens to the speed of sound in a medium when the
bulk modulus of the medium increases?
a. faster
b. slower
c. u n c h a n g e d

A

a. faster

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23
Q

—–resolution is determined by the spatial pulse length.
a . r a d i a l
b. image
c. axial
d. a n g u l a r

A

c. axial
a . r a d i a l

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24
Q

If a wave’s amplitude is doubled, what happens to the power?
a. nothing
b. halved
c. doubled
d. quadrupled

A

d. quadrupled

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25
Q

If the level of an acoustic variable ranges from 55 to 105, what is the amplitude?
a. 105
b. 50
c. 25
d. 55

A

c. 25

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26
Q

Power of sound has units of
a. dB
b. dB/cm
c. watts
d. watts/cm

A

c. watts

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27
Q

If the intensity of a sound beam remains unchanged while the beam area is reduced in half, what has happened to the power?
a. quadrupled
b. doubled
c. halved
d. unchanged

A

c. halved

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28
Q

Which of these intensities is smallest?
a. SATP
b. SPTP
C. SATA

A

C. SATA

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29
Q

The duty factor for continuous wave ultrasound is
а. 10.0
b. 1%
c. 1.0
d. 0 . 0 %

A

c. 1.0

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30
Q

What is the minimum value of the duty factor?
a. 10.0
b. 1%
c. 1.0
d. 0.0%

A

d. 0.0%

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31
Q

What are the units of intensity?
a. watts
b. decibels
c. watts/cm squared
d. d e c i b e l s

A

c. watts/cm squared

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32
Q

What happens to the speed of sound in a medium when the bulk modulus of the medium decreases?
a. faster
b. Slower
c . u n c h a n g e d

A

b. Slower

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33
Q

The units of attenuation
a r e ——- this is a ——–scale.
a. mm/cm, parametric
b. dB/m, multiplicative
c. none, relative
d. dB, logarithmic

A

d. dB, logarithmic

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34
Q

Sound intensity is decreased by 75%. How many decibels of attenuation is this?
‘a. 6dB
b. 9dB
c. 5dB
d. 10dB

A

a. 6dB

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35
Q

The fundamental frequency of a transducer is 2.5MHz. What
is the second harmonic frequency?
a. 1.25MHz
b. 4.5MHz
c. 5MHz
d. 5cm

A

c. 5MHz

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36
Q

A pulse emitted by a transducer and is traveling in soft tissue. The go-return time, or time-of-flight, of a sound pulse is 130
microseconds.
What is the reflector depth?
a. 10 cm
b. 10 mm
.c 10 m
d. 130 mm
e. 13 cm

A

a. 10 cm

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37
Q

If a 5MHz sound wave is traveling in the tissues listed below, which will have the longest wavelength?
a. Fat
b. Air
c. Muscle
d. Bone

A

d. Bone

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38
Q

If a 5MHz sound wave is traveling in the tissues listed below, which wil
l have the shortest wavelength?
a. Fat I
b. A i r
c. Muscle
d. Bone

A

b. A i r

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39
Q

What is the approximate attenuation coefficient of 1MHz US in soft tissue? “
a. 0.5dB/cm
b . 1 c m
c. 3dB/cm
d. 1dB

A

a. 0.5dB/cm

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40
Q

The rayl is the unit of:
a. intensity
b. reflectance
c. density
d . impedance

A

d . impedance

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41
Q

Impedance is the —-of —— and—–

a. product, propagation speed, density
b. sum, stiffness, density
c. quotient, stiffness, propagation speed
d. difference, attenuation, density

A

a. product, propagation speed, density

42
Q

What are attenuation’s three components?

A

Reflection, Scattering, absorption

43
Q

For soft tissue, the
approximate attenuation coefficient in dB/cm is equal to one-half
in
a. wavelength, mm
b. frequency, Hz
c. frequency, MHz
d. impedance, rayls

A

c. frequency, MHz

44
Q

As the impedances of two
media become vastly different, the

a . reflection increases
b. transmission increases
c. refraction increases
d. absorption increases

A

reflection increases

45
Q

The angle between an US pulse and the boundary between two media is 90°. What is this called?
a. direct incidence
b. oblique incidence
c. indirect incidence
d. orthogonal incidence

A

d. orthogonal incidence

46
Q

The angle between an US pulse and the boundary between two media is 56°. This is called:
a. direct incidence
b. oblique incidence
c. indirect incidence
d. orthogonal incidence

A

b. oblique incidence

47
Q

Refraction only occurs if there

a. normal incidence & different impedances
b. indirect intensity &different propagation speeds
c. oblique incidence & different propagation speeds
d. oblique frequency & identical impedances

A

c. oblique incidence & different propagation speeds

48
Q

With normal incidence, what factors affect refraction of US?
a. propagation speeds
b. frequencies
c. attenuation coefficients
d. none of the above

A

d. none of the above

49
Q

(True or False) With right angle incidence, reflections are always generated at a boundary if the propagation speeds of the media are different.

A

False

50
Q

——–is a redirection of US in many directions as a result of a rough boundary between two media.
a. refraction
b. Rayleigh scattering
c . scattering
d. reflection

A

c . scattering

51
Q

Which of the following tissues is most likely to create Rayleigh scattering?
a. red blood cells
b. muscle
c fat
d. bone

A

a. red blood cells

52
Q

(True or False) With normal incidence the angle is 180°.

A

False

53
Q

Under which of the follow
ing conditions is axial resolution improved?
a. decreased spatial pulse length
b. decreasedpulseamplitude
c. decreased imaging depth
d. decreased pixel size
e. decreased beam diameter

A

a. decreased spatial pulse length

54
Q

Snell’s law describes physics
of
a. ultrasound
b. reflection
c. refraction
d. transmission

A

c. refraction

55
Q

The most likely amount of
reflection at a boundary between soft tissues is:
a. 1%
b. 22%
с. 34%
d. 99%

A

a. 1%

56
Q

The most typical amount of
transmission at a boundary in biologic media is:
a. 1%
b. 22%
c. 34%
d. 99%

A

d. 99%

57
Q

Sound si traveling from medium 1to medium 2. Propagation speeds of My and M2 are 1,600m/s and 1,500m/s, respectively. There is oblique incidence.
a. angle of incidence › angle of reflection
b. angle of incidence = angle of reflection
c. angle of incidence <angle of reflection

A

b. angle of incidence = angle of reflection

58
Q

(True or False) Doppler shifts always occur if the sound source and the receiver are in motion.

A

False

59
Q

which of the following is associated with power mode doppler?

a. poor temporal resolution and flash artifact
b. lower sensitivity and good temporal resolution
.c high sensitivity and high frame rates
d. flash artifact and reduced sensitivity
e. good temporal resolution and flash artifact

A

a. poor temporal resolution and flash artifact

60
Q

The Doppler shift is a measure of:

a. ratio of incident frequency to reflector frequency
b. sum of incident frequency & reflected frequency
c. difference between incident &reflected frequency
d. product of incident and reflected frequencies

A

c. difference between incident &reflected frequency

61
Q

(True or False) The sonographer cannot change, directly or indire
ctly, the duty factor of an US machine.

A

False

62
Q

Depth calibration of a machine measures 100mm spaced wires to be 90mm apart. Scanning reflectors 50 mm apart, what wil the machine calculate the distance to be?
a. 40mm
b. 45mm
.c 60mm
d. 65mm

A

b. 45mm

63
Q

(True or False) There have not been biological effects from US found in the laboratory

A

False

64
Q

In an analog scan converter, what component stores the image data?

a. computer memory
b. video tape recorder
c. dielectric matrix
d. none of the above

A

c. dielectric matrix

65
Q

Which has the correct order?
mega-milli-kilo-micro-

a. 106 10-6 103 10-3
b. 10-6 106 102 10-3
с. 10 6 10-3 103 10-6
d. 106 10-6 103 10-4

A

c. 10 6 10-3 103 10-6

66
Q

How many cm are
60 millimeters?
a. 600
b. 6
с. 0.6
d. 0.06

A

b. 6

67
Q

(True or False) Lateral resolution is also called:
axial
azimuthal
longitudinal
range

A

azimuthal

68
Q

Whcih has the corect units?

Freq, Speed, Intens, Atten
a. Hz mm/s joules dB/cm
b. mHz m/sec Wc/m2 DB
c. KH2 mm/us Wc/m3 dB/cm

A

b. mHz m/sec Wc/m2 DB

69
Q

What increases patient exposure?
a. exam time
b. frequency
c. video taping
d. Wave length

A

a. exam time

70
Q

Shadowing may result from high amount of reflection of US energy. Tor F

A

True

71
Q

Where are harmonics created?
a, in the receiver
b. in the transducer
c. in the tissues
d. in the beam former

A

c. in the tissues

72
Q

How is range ambiguity artifact eliminated?

a. lower the PRF
b. raise the PRF
.c increase the gain
d. use a lower frequency
transducer

A

a. lower the PRF

73
Q

How is lateral resolution measured fi this test object is scanned from the top?

a. measure the distance from Ato E
b. measure length of line C and divide by 2
c. measure the length of line B

A
74
Q

For Doppler, which incident angle results in no shift?
a. 180°
b. 90°
с. 0°

A
75
Q

Which transducer would be best to image superficial structures?

a. small diameter, high frequency
b. small diameter, low frequency
.c large diameter, high frequency
d. large diameter, low frequency

A

a. small diameter, high frequency

76
Q

A transducer with more than one active element is called:

a. multipurpose
b. annular
.c mechanical
d. array

A

d. array

77
Q

How many bits are needed to represent 16 shades of grey?
a. 2
b. 3
c. 4
d. 5

A

c. 4

78
Q

What information does Doppler shift provide?

a. flow
b. cardiac output
c. velocity
d. speed

A

c. velocity

79
Q

A sound wave is a pressure wave made of compressions and rarefactions

A

true

80
Q

A hydrophone is used to measure
a. velocity
b. frequency
c. intensity
d. phase

A

b. frequency
c. intensity

81
Q

Images on videotape are stored using:
a. magic
b. magnetism
c. Paper
d. Computer Memory

A

b. magnetism

82
Q

Circumferences may be measured in unit of:
a. cm
b. cm squared
c. cubic cm
d. cubits

A

a. cm

83
Q

Decimal uses a base of 10, binary uses a base of
a. 1
b. 2
c. 5
d. 10

A

b. 2

84
Q

If the frame rate increases and the lines per frame is unchanged, what else must happen?
a US speed increases .
b frequency increases
c.depth increases
d. depth decreases

A

d. depth decreases

85
Q

Which of these cannot be performed by a sonographer?

a. adjust overall gain
b. clean VCR recording heads
c. clean pixels
d. adjust time gain compensation

A

c. clean pixels

86
Q

which of the following is not a beam steering technique for a mechanical scan head
a. rotating wheel
b. phased beam
c. oscillating disc
d. oscillating mirror

A

b. phased beam

87
Q

A system which was working well now does not display clear images in the far field. This may be a problem with the
a. transducer
b. receiver
c. monitor
d. scan converter

A

a. transducer
b. receiver
c. monitor
d. scan converter

88
Q

How many decibels is related to a 90% decrease in imaging power?
a. -1 dB
b. -10 dB .
c -90 dB
d. -10dB

A

b. -10 dB

89
Q

If the output of an US machine is calibrated in dB and the
the output is increased by 20db, increased
a. 100 times
b. 1,000,000 times
c. 20 times
d. 10 times

A

a. 100 times

90
Q
  • Which has the greatest amount of attenuation?
    .a bone
    b. fat
    c. water
    d. muscle
A

.a bone

91
Q

Which of the following will result in the greatest number of shades of gray in a digital image display?

.a large pixels with many bits/pixel
b. small pixels with few bits/pixel
c. many VT lines per frame
d. high contrast
e. narrow dynamic range

A

.a large pixels with many bits/pixel

92
Q

What is not the responsibility
of the sonographer?
a. clean the filters
b. adjust the recorder
c. adjust converter matrix
d. change paper

A

c. adjust converter matrix

93
Q

With good images on the display but not on the printer, one should

a. increase the gain
b. check the scan head
c. check scan converter
d. adjust the recorder

A

d. adjust the recorder

94
Q

To measure the US
beam - intensity, use a

a. calibrated hydrophone
b. lateral oscilloscope
c. water filled phantom
d. tissue equivalent phantom

A

a. calibrated hydrophone

95
Q

When the US machine displays only strong reflecting objects and nothing else, the sonographer should

a. adjust far gain
b. increase output power
c. increase lateral resolution
d. adjust TGC

A

b. increase output power

96
Q

Compression is used to

a. decrease the amplitude
b. decrease the range of
amplitudes
c. decrease the range of frequencies

A

b. decrease the range of
amplitudes

97
Q

Reject is used to

a. adjust the appearance of highly reflective objects
b. adjust the appearance of lowly reflective objects
c. improve axial resolution d. improve digital scan
conv
erter sensitivity

A

b. adjust the appearance of lowly reflective objects

98
Q

If a reflector is moved twice as far away from the transducer, how will this affect the time- of-flight of a sound pulse?

a. quadruple it
b. double it
c. no change
d. halve it

A

b. double it

99
Q

A single element transducer is focused

a. by the manufacturer
b. cannot be focused
c. by increasing power
d. by the sonographer

A

a. by the manufacturer

100
Q

An US machine has a digital
scan converter but has an analog input signal. The machine needs to have a

a. hybrid multiplexer
b. m o d e m
c. analog to digital converter
d. digital monitor

A

c. analog to digital converter

Ultrasound Physics (11 decks)

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