2. Ultrasound Flashcards by Jenessa Beatty

A wave is a traveling variation in quantities called wave _______.

a. lengths
b. variables
c. cycles
d. periods

b. variables

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Sound is a traveling variation in quantities called ________ variables.

a. wave
b. pressure
c. density
d. acoustic

d. acoustic

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Ultrasound is sound with a frequency greater than ___ Hz.

a. 2
b. 15
c. 20,000
d. 1540

c. 20,000

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Acoustic variables include ______, ________, and particle motion.

a. stiffness, density
b. hardness, impedance
c. amplitude, intensity
d. pressure, density

d. pressure, density

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Which of the following frequencies is in the ultrasound range?

a. 15 Hz
b. 15,000 Hz
c. 15 kHz
d. 30,000 Hz
e. 0.004 MHz

d. 30,000 Hz

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Frequency is the number of ______ an acoustic variable goes through in a second.

a. cycles
b. amplitudes
c. pulse lengths
d. Duty factors

a. cycles

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The unit of frequency is ________, which is abbreviated as _______.

a. hertz, Hz
b. megahertz, MHz
c. kilohurts, khts
d. cycles, cps

a. hertz, Hz

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Period is the _______ that it takes for one cycle to occur.

a. length
b. amplitude
c. time
d. height

c. time

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Period decreases while ______ increases.

a. wavelength
b. pulse length
c. frequency
d. bandwidth

c. frequency

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Wavelength is the length of _________over which one cycle occurs.

a. time
b. space
c. propagation
d. power

b. space

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Propagation speed is the speed with which a(n) _______ moves through a medium.

a. wave
b. particle
c. frequency
d. attenuation

a. wave

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Wavelength is equal to _____ _______ divided by _________.

a. propagation speed, frequency
b. media density, stiffness
c. pulse length, frequency
d. wave amplitude, period

a. propagation speed, frequency

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The _______ and ________ of a medium determine propagation speed.

a. amplitude, intensity
b. wavelength, period
c. impedance, attenuation
d. density, stiffness

d. density, stiffness

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Propagation speed increases if _______ is increased.

a. amplitude
b. frequency
c. density
d. stiffness

d. stiffness

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The average propagation speed in soft tissue is ______ m/s or ________ mm/us.

a. 10, 3
b. 1540, 1.54
c. 3, 10
d. 1.54, 1540

b. 1540, 1.54

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Propagation speed is determined by the _______.

a. frequency
b. amplitude
c. wavelength
d. medium

d. medium

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Place the following classifications of matter in order of increasing sound propagation speed.

a. gas, solid, liquid
b. solid, liquid, gas
c. gas, liquid, solid
d. liquid, solid, gas

c. gas, liquid, solid

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The wavelength of 7 MHz ultrasound in soft tissues is ____ mm.

a. 1.54
b. 0.54
c. 0.22
d. 3.33

c. 0.22

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Wavelength in soft tissues ______ while frequency increases.

a. is constant
b. decreases
c. increases
d. weakens

b. decreases

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It takes ________ us for ultrasound to travel 1.54 cm in soft tissue.

a. 10
b. 0.77
c. 154
d. 100

a. 10

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Propagation speed in bone is _______ that in soft tissues.

a. lower than
b. equal to
c. higher than
d. 10 m/s greater than

c. higher than

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Sound travels fastest in ________.

a. air
b. helium
c. water
d. steel

d. steel

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Solids have higher propagation speeds than liquids because they have greater ________.

a. density
b. stiffness
c. attenuation
d. propagation

b. stiffness

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Sound travels most slowly in _________.

a. gases
b. liquids
c. tissue
d. bone

a. gases

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Sound is a _______ __________ wave. a. mechanical expressional b. electromagnetic transverse c. electromagnetic longitudinal d. mechanical longitudinal

d. mechanical longitudinal

If propagation speed is doubled (a different medium) and frequency is held constant, the wavelength is _________. a. decreased b. doubled c. halved d. unchanged

b. doubled

If frequency in soft tissue is doubled, propagation speed is ________. a. decreased b. doubled c. halved d. unchanged

d. unchanged (determined by the medium)

If wavelength is 2 mm and frequency is doubled, the wavelength becomes ____ mm. a. 4 b. 1 c. 2.5 d. unchanged

b. 1

Waves can carry ______ from one place to another. a. information b. density c. impedance d. speed

a. (information or energy)

From given values for propagation speed and frequency, ________ can be calculated. a. amplitude b. impedance c. wavelength d. intensity

c. wavelength

If two media have different stiffnesses, the one with the higher stiffness will have the higher propagation speed. T or F?

True

The second harmonic of 3 MHz is _____ MHz. a. 2 b. 3.2 c. 6 d. 9

c. 6

Odd harmonics of 2 MHz are _____ MHz. a. 1, 3, 5 b. 2, 4, 6 c. 6, 9, 12 d. 6, 10, 14 e. 10, 12, 14

d. 6, 10, 14

Even harmonics of 2 MHz are ____ MHz. a. 1, 3, 5 b. 2, 4, 6 c. 4, 8, 12 d. 6, 10, 14 e. 10, 12, 14

c. 4, 8, 12

Nonlinear propagation means that _________. a. the sound beam does not travel in a straight line b. propagation speed depends on frequency c. harmonics are not generated d. the waveform changes shape while it travels

d. the waveform changes shape while it travels

In nonlinear propagation, additional frequencies appear that are ______ and _______ multiples of the fundamental frequency. They are called _______. a. double, triple, harmonics b. double, triple, subharmonics c. odd, even, harmonics d. odd, even, subharmonics

c. odd, even, harmonics

If the density of a medium is 1000 kg/m3 and the propagation speed is 1540 m/s, the impedance is _______ rayls. a. 1540 b. 2540 c. 540 d. 1,540,000

d. 1,540,000

If two media have the same propagation speed but different densities, the one with the higher density will have the higher impedance. T or F?

True

Impedance is ______ multiplied by ______ ______. a. density, propagation speed b. frequency, oblique incidence c. wavelength, propagation speed d. attenuation, PD

a. density, propagation speed

The abbreviation CW stands for ______. a. corrected waveform b. continuous window c. continuous wave d. contrast waveform

c. continuous wave

PRF is the number of ______ occurring in 1 second. a. cycles b. pulses c. periods d. wavelengths

b. pulses

Pulse-repetition ________ is the time from the beginning of one pulse to the beginning of the next. a. frequency b. time c. duration d. period

d. period

The PRP _______ while PRF increases. a. increases b. decreases c. is unchanged d. is undetermined

b. decreases

PD is the ________ it takes for a pulse to occur. a. frequency b. time c. duration d. period

b. time

SPL is the _________ of ________ that a pulse occupies while it travels. a. length, time b. length, space c. amount, amplitude d. intensity, energy

b. length, space

________ is the fraction of time that pulsed ultrasound is actually on. a. pulse duration b. pulse intensity c. duty factor d. duty frequency

c. duty factor

PD equals the number of cycles in the pulse multiplied by ________. a. frequency b. period c. wavelength d. amplitude

b. period

SPL equals the number of cycles in the pulse multiplied by _______. a. frequency b. period c. wavelength d. amplitude

c. wavelength

The DF of continuous wave sound is ___. a. 1 b. undefined c. 1540 d. 10

a. 1

If the wavelength is 2 mm, the SPL for a three-cycle pulse is ___ mm. a. 6 b. 0.6 c. 0.4 d. 1

a. 6

The SPL in soft tissue for a two-cycle pulse of frequency 5 MHz is ___ mm. a. 6 b. 0.6 c. 0.4 d. 1

b. 0.6 (soft tissue propagation speed is 1.54 mm/us; wavelength is 0.3 mm)

The PD in soft tissue for a two-cycle pulse of frequency 5 MHz is ____ us. a. 6 b. 0.6 c. 0.4 d. 1

c. 0.4 (period is 0.2 us; soft tissue is irrelevant)

For a 1 kHz PRF, the PRP is ____ ms. a. 6 b. 0.6 c. 0.4 d. 1

d. 1 (1000 pulses per second; 1/1000 second from one pulse to the next)

How many cycles are there in 1 second of continuous wave 5-MHz ultrasound? a. 5 b. 500 c. 5000 d. 5,000,000 e. none of the above

d. 5,000,000

How many cycles are there in 1 second of pulsed 5-MHz ultrasound with a DF of 0.01 (1%)? a. 5 b. 500 c. 5000 d. 5,000,000 e. none of the above

e. none of the above (50,000)

For pulsed ultrasound, the DF is always ______ 1. a. less than b. greater than c. equal to

a. less than

______ is a typical DF for sonography. a. 0.1 b. 0.5 c. 0.7 d. 0.9

a. 0.1

Amplitude is the maximum _______ that occurs in an acoustic variable. a. time b. variation c. distance d. frequency

b. variation

Intensity is the _________ in a wave divided by ______. a. amplitude, power b. area, power c. power, amplitude d. power, area

d. power, area

A unit for intensity is ______. a. mW/cm2 b. MHz/cm2 c. cm/MHz d. mm/cm2

a. mW/cm2 (also W/cm2)

If power is doubled and area remains unchanged, intensity is _______. a. unchanged b. halved c. doubled d. quadrupled

b. halved

If both power and area are doubled, intensity is ______. a. unchanged b. halved c. doubled d. quadrupled

a. unchanged

If amplitude is doubled, intensity is ________. a. unchanged b. halved c. doubled d. quadrupled

d. quadrupled

If a sound beam has a power of 10 mW and a beam area of 2 cm2, the spatial average intensity is ______ mW/cm2. a. 10 b. 2 c. 20 d. 5

d. 5

Attenuation is the reduction in ______ and ________ as a wave travels through a medium. a. amplitude, intensity b. amplitude, wavelength c. intensity, speed d. amplitude, speed

a. amplitude, intensity

Attenuation consists of ______, ________, and _______. a. amplitude, intensity, power b. amplitude, wavelength, power c. absorption, reflection, scattering d. scattering, amplitude, speed

c. absorption, wavelength, power

The attenuation coefficient is attenuation per ________ of sound travel. a. second b. centimeter c. cycle d. wavelength

b. centimeter

Attenuation and the attenuation coefficient are given in units of ______ and _____, respectively. a. dB, dB/cm b. mW/cm2, mW {VO6} c. dB, dB/cm2 d. dB2, mW

a. dB, dB/cm

For soft tissues, there is approx. _____ dB of attenuation per centimeter for each MHz of frequency. a. 1.54 b. 3 c. 5 d. 0.5

d. 0.5

For soft tissues, the attenuation coefficient at 3 MHz is approx ___. a. 15 dB/cm b. 3 dB c. 1.5 dB/cm d. 15 cm

c. 1.5 dB/cm

The attenuation coefficient in soft tissue ______ while frequency increases. a. increases b. decreases c. weakens d. decelerates

a. increases

For soft tissue, if frequency is doubled, attenuation is _____. If path length is doubled, attenuation is ______. If both frequency and path length are doubled, attenuation is _____. a. doubled, doubled, quadrupled b. doubled, doubled, doubled c. doubled, quadrupled, quadrupled d. quadrupled, quadrupled, quadrupled

a. doubled, doubled, quadrupled

If frequency is doubled and path length is halved, attenuation is _______. a. doubled b. halved c. quadrupled d. unchanged

d. unchanged

Absorption is the conversion of ________ to ______. a. energy, amplitude b. heat, sound c. sound, heat d. sound, intensity

c. sound, heat

Absorption can be greater than attenuation in a given medium at a given frequency. T or F?

False. (attenuation = absorption + scattering)

Attenuation is higher in bone than in soft tissue. T or F?

True

The imaging depth (penetration) ______ while frequency increases. a. increases b. decreases c. is unchanged d. is undetermined

b. decreases

If the intensity of a 4 MHz ultrasound entering soft tissue is 2 W/cm2, the intensity at a depth of 4 cm is _______ W/cm2. a. 0.16 b. 0.32 c. 0.48 d. 0.64

b. 0.32 (attenuation is 8 dB, and intensity ratio is 0.16)

The depth at which half-intensity occurs in soft tissues at 7.5 MHz is _______. a. 0.6 cm b. 0.7 cm c. 0.8 cm d. 0.9 cm

c. 0.8 cm (0.5 x 7.5 MHz x 0.8 cm = 3 dB)

If the intensity of a 40 MHz ultrasound entering soft tissue is 2 W/cm2, the intensity at a depth of 4 cm is ____ W/cm2. a. 0.00002 b. 0.000002 c. 0.0000002 d. 0.00000002

d. 0.00000002 (attenuation is 80 dB, and intensity ratio is 0.00000001)

When ultrasound encounters a boundary with perpendicular incidence, the _______ of the tissues must be different to produce a reflection (echo). a. impedances b. densities c. speeds d. hardnesses

a. impedances

With perpendicular incidence, two media _____ and the incident _____ must be known to calculate the reflected intensity. a. impedances, amplitude b. amplitudes, impedance c. impedances, intensity d. amplitudes, intensity

c. impedances, intensity

With perpendicular incidence, two media _____ must be known to calculate the intensity reflection coefficient. a. densities b. speeds c. hardnesses d. impedances

d. impedances

For an incident intensity of 2 mW/cm2 and impedances of 49 and 51 rayls, the reflected intensity is ______ mW/cm2, and the transmitted intensity is _____ mW/cm2. a. 0.8, 1.2 b. 0.08, 1.92 c. 0.008, 1.992 d. 0.0008, 1.9992

d. 0.0008, 1.9992

If the impedances of the media are equal, there is no reflection. T or F?

True, for perpendicular incidence

With perpendicular incidence, the reflected intensity depends on the _____. a. density difference b. impedance difference c. impedance sum d. b and c e. a and b

d (difference in numerator; sum in denominator)

Refraction is a change in _______ of sound when it crosses a boundary. Refraction is caused by a change in ______ ______ at the boundary. a. speed, sound direction b. direction, propagation speed c. amplitude, media impedance d. direction, media attenuation

b. direction, propagation speed

Under what two conditions does refraction not occur? a. perpendicular incidence or equal media propagation speeds b. oblique incidence or equal media propagation speeds c. perpendicular incidence or unequal media propagation speeds d. oblique incidence or unequal media propagation speeds

a. perpendicular incidence or equal media propagation speeds

The low speed of sound in fat is a source of image degradation because of refraction. If the incidence angle at a boundary between fat (1.45 mm/us) and kidney (1.56 mm/us) is 30 degrees, the transmission angle is ______ degrees. a. 28 b. 30 c. 32 d. 33

c. 32

Reflection of sound in many directions while it encounters rough media junctions or particle suspensions (heterogeneous media) is called __________. a. specular b. refraction c. propagation d. scattering

d. scattering

Backscatter helps make echo reception less dependent on incident angle. T or F?

True

What must be known to calculate the distance to a reflector? a. attenuation, speed, density b. attenuation and impedance c. attenuation and absorption d. travel time and speed e. density and speed

d. travel time and speed

No reflection will occur with perpendicular incidence if the media ________ are equal. a. impedances b. speeds c. densities d. attenuations

a. impedances

Scattering occurs at smooth boundaries and within homogeneous media. T or F?

False