2. Ultrasound Flashcards
A wave is a traveling variation in quantities called wave _______.
a. lengths
b. variables
c. cycles
d. periods
b. variables
Sound is a traveling variation in quantities called ________ variables.
a. wave
b. pressure
c. density
d. acoustic
d. acoustic
Ultrasound is sound with a frequency greater than ___ Hz.
a. 2
b. 15
c. 20,000
d. 1540
c. 20,000
Acoustic variables include ______, ________, and particle motion.
a. stiffness, density
b. hardness, impedance
c. amplitude, intensity
d. pressure, density
d. pressure, density
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
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
The unit of frequency is ________, which is abbreviated as _______.
a. hertz, Hz
b. megahertz, MHz
c. kilohurts, khts
d. cycles, cps
a. hertz, Hz
Period is the _______ that it takes for one cycle to occur.
a. length
b. amplitude
c. time
d. height
c. time
Period decreases while ______ increases.
a. wavelength
b. pulse length
c. frequency
d. bandwidth
c. frequency
Wavelength is the length of _________over which one cycle occurs.
a. time
b. space
c. propagation
d. power
b. space
Propagation speed is the speed with which a(n) _______ moves through a medium.
a. wave
b. particle
c. frequency
d. attenuation
a. wave
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
The _______ and ________ of a medium determine propagation speed.
a. amplitude, intensity
b. wavelength, period
c. impedance, attenuation
d. density, stiffness
d. density, stiffness
Propagation speed increases if _______ is increased.
a. amplitude
b. frequency
c. density
d. stiffness
d. stiffness
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
Propagation speed is determined by the _______.
a. frequency
b. amplitude
c. wavelength
d. medium
d. medium
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
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
Wavelength in soft tissues ______ while frequency increases.
a. is constant
b. decreases
c. increases
d. weakens
b. decreases
It takes ________ us for ultrasound to travel 1.54 cm in soft tissue.
a. 10
b. 0.77
c. 154
d. 100
a. 10
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
Sound travels fastest in ________.
a. air
b. helium
c. water
d. steel
d. steel
Solids have higher propagation speeds than liquids because they have greater ________.
a. density
b. stiffness
c. attenuation
d. propagation
b. stiffness
Sound travels most slowly in _________.
a. gases
b. liquids
c. tissue
d. bone
a. gases
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
