Tests/Quizzes Flashcards
(283 cards)
1
Q
Which of the following is true of all waves?
a) they travel through a medium
b) all carry energy from one site to another
c) their amplitudes do not change
d) they travel in a straight line
A
b) all carry engery from one site to another
2
Q
The intensity of a signal declines from 1.5 mW/cm2 to 0.75 mW/cm2. How many decibels is this change in intensity?
A
-3dB
3
Q
Which of the following describes the characteristics of a sound wave?
a) longitudinal, non-mechanical
b) mechanical, transverse
c) transverse, acoustic
d) mechanical, longitudinal
A
d) mechanical, longitudinal
4
Q
Sound is best described as:
a) a series of compressions and rarefactions
b) a transverse wave
c) a wave that humans can hear
d) an oblique displacement of acoustic energy
A
a) a series of compressions and rarefactions
5
Q
What are three acoustic variables?
A
partical motion (distance), density, and pressure
6
Q
Ultrasound is defined as a sound with a frequency of:
a) greater than 20,000 kHz
b) less than 1 kHz
c) greater than 10 MHz
d) greater than 0.02 MHz
A
d) greater than 0.02 MHz
7
Q
log 100,000 = x
A
x = 5
8
Q
log (100/2) = x
A
x = 1.7
9
Q
log 2 = x
A
x = 0.3
10
Q
log 8 = x
A
x = 0.9
11
Q
An increase in power by a factor of 10,000 is equal to an increase of ___ dB.
A
40 dB
12
Q
True/False?
If the amplitude of a wave is increased to 3 times its original value, the intensity is increased by 6 times.
A
FALSE
13
Q
True/False?
Propagation speed increases as frequency increases.
A
FALSE
14
Q
Which of the following characteristics will create the fastest speed of sound?
a) high density, high stiffness
b) low density, high stiffness
c) high density, low stiffness
d) low density, low stiffness
A
b) low density, high stiffness
15
Q
If the power in a beam is 1 W and the area is 5 cm2, what is the beams intensity?
A
I = 0.2 W/cm2
or 1/5 W/cm2
16
Q
What is the wavelength of 2 MHz sound in soft tissue?
a) 1.54 mm
b) 0.77 mm
c) 0.51 mm
d) 0.31 mm
A
b) 0.77 mm
17
Q
What is a decibel?
a) the absolute value of a number
b) a range of values
c) a relationship between 2 numbers
d) none of the above
A
c) a relationship between 2 numbers
18
Q
The intensity of an ultrasound wave is changed by -6 dB. This means that the current intensity is ___ as much as its original level.
a) one tenth
b) four times
c) one fourth
d) one sixth
A
c) one fourth
19
Q
As sound propagates through a medium, the total power in the wave decreases. What is this entire process called?
a) absorption
b) scattering
c) attenuation
d) reflection
A
c) attenuation
20
Q
Attenuation is determined by which of the following factors?
a) density and stiffness of the medium
b) frequency of sound and propagation
c) PRF of sound and path length
d) path length and frequency of sound
A
d) path length and propagation of sound
21
Q
Which of the following is not one of the physical processes that contributes to attenuation of ultrasound waves passing through soft tissue?
a) reflection
b) redirection of sound in many directions
c) focusing
d) conversion of acoustic energy to heat
A
c) focusing
22
Q
A sound wave reaches a rough or irregular border between 2 media. Under these explicit circumstances, which process is most likely to occur?
a) backscatter reflection
b) specular reflection
c) Rayleigh scattering
d) refraction
A
a) backscatter reflection
23
Q
A sound beam travels 9 cm in soft tissue. The attenuation coefficient is 3 dB/cm. What is the total attenuation that the sound beam experienced?
a) 9 dB
b) 3 dB
c) 27 dB
d) 18 dB
A
c) 27 dB
24
Q
Acoustic impedance is property of the ___ and has units of ___.
a) source and medium, Imps
b) medium, dB
c) medium, rayls
d) medium, Ohms
A
c) medium, rayls
25
Which 2 attributes help establish the acoustic impedance of a medium?
a) density and temperature
b) density and stiffness
c) stiffness and elastance
d) elasticity and compressibility
b) density and stiffness
26
Which value is closest to the impendance of soft tissue?
a) 1.5 kRayls
b) 2.5 dRayls
c) 19 MRayls
d) 2,000,000 Rayls
d) 2,000,000 Rayls
27
A sound wave with an intensity of 50 W/cm2 strikes a boundary and is totally reflected. What is the intensity reflection coefficient?
a) 50 W/cm2
b) 25 W/cm2
c) 0 W/cm2
d) 100%
e) 0
d) 100%
28
A sound wave with an intensity of 50 W/cm2 strikes a boundary and is totally reflected. What is the reflected intensity?
a) 50 W/cm2
b) 25 W/cm2
c) 0 W/cm2
d) 100%
e) 0
a) 50 W/cm2
29
Which of the following terms does not belong with the others?
a) orthogonal
b) oblique
c) normal
d) perpendicular
b) oblique
30
Sound that is traveling in Jell-o passes through an interface at 90 degrees and continues to travel in whipped cream. The impedance of Jell-o and whipped cream are nearly identical. What percentage of the intensity is transmitted?
a) 2%
b) 25%
c) 78%
d) 99%
d) 99%
31
A sound pulse travels in Medium 1 and strikes an interface with another tissue, Medium 2, at 30 degrees. The angle of transmission is 10 degrees. In which medium does sound travel slowest?
Medium 2
32
A sound wave strikes a boundary with normal incidence. The impedance of the two media are identical. What percentage of the sound wave is refracted?
0%
33
Two sound waves with frequencies of 5 and 3 MHz travel to a depth of 8 cm in a medium and then reflect back to the surface of the body. Which acoustic wave arrives first at the surface of the body?
a) the 5MHz wave
b) the 3 MHz wave
c) neither
d) cannot be determined
c) neither
34
Decibel notation is a ___ between 2 numbers.
a) difference
b) sum
c) product
d) ration
d) ratio
35
The logarithm of a numeral is defined as how many times ___ must be multiplied together to get that number.
a) 1
b) 2
c) 5
d) 10
d) 10
36
Which of the following reports the relative strength of an ultrasound wave?
a) decibels
b) watts
c) W/cm2
d) pascals
a) decibels
37
What is the major reason that the speed of sound in bone is faster than soft tissue?
a) bone is stiffer
b) bones are generally larger than soft tissue
c) bone is more dense
d) there is no difference, the speed of sound is the same for both
a) bone is stiffer
38
If you consider a speaker as a source of sound, what happens to the density of the air when the speaker diaphragm moves forward (toward the listener)?
a) the density increases
b) the density decreases
c) a region of rarefaction is created
d) no change in density, the density of air is only changed if the temperature changes
a) the density increases
39
Ultrasound creates an image by considering how long it takes for the sound to bounce off of a reflector and then return to the transducer. If the speed of sound in air is 330 m/s and you receive an echo 10 seconds after you send the sound pulse, how far away is the wall that the sound was reflected from?
1650 m
40
How many cycles occur in a 10 second time period for a 10 MHz sound?
100 cycles
41
How many msec are in 1 second?
1,000 msec
42
Can sound travel in a vacuum?
a) no; sound requires a medium that can vibrate
b) yes; just like light, sound can propogate as long as there is energy
c) no; sound would destroy the vacuum and let air in
d) yes; you just need a sound source and that's enough
a) no; sound requires a medium that can vibrate
43
Which is most likely to produce scatter?
a) RBC
b) diaphragm
c) skull
d) distilled water
a) RBC
44
Which tissue type has the lowest rate of attenuation?
a) blood
b) fat
c) bone
d) soft tissue
a) blood
45
If the time between transmission and reception of the echo is 26 microseconds, how far is the reflector from the transducer?
a) 2 cm
b) 8 cm
c) 4 cm
d) 10 cm
a) 2 cm
46
What effects the magnitude of the scattered ultrasound intensity?
a) frequency
b) number of scatters
c) size of scatters
d) all of the above
d) all of the above
47
An interface composed of which of the following is most likely to generate the strongest echo?
a) fat and soft tissue
b) air and soft tissue
c) bone and soft tissue
d) echo strength does not depend of composition of interface
b) air and soft tissue
48
In what form is ultrasound energy dissipated by soft tissue?
a) heat
b) radio waves
c) light
d) X-rays
a) heat
49
If the reflected intensity is 50% of the incident intensity for a 3 MHz sound wave, what is the percent of transmitted intensity? Assume specular reflection.
50%
50
A sound wave encounters a large interface composed of soft tissue and fat. What thickness of the fat layer produces the strongest echo?
a) 0.5 mm
b) 2.0 mm
c) 1.0 mm
d) independent of thickness
d) independent of thickness
51
What interaction causes a change of direction in the sound beam as it moves from one medium into another?
a) absorption
b) reflection
c) interference
d) refraction
d) refraction
52
What is an exaple of specular reflection?
a) diaphragm
b) RBC
c) liver parenchyma
d) amniotic fluid
a) diaphragm
53
If ultrasound intensity is reduced by a factor of 2, what is the intensity change in decibels?
-3 dB
54
What factor, other than output intensity, affects the echo intensity detected by the transducer?
a) transmitted frequency
b) acoustic velocity
c) beam width
d) pulse length
a) transmitted frequency
55
What is the duty factor for an ultrasound pulse at 5 MHz that contains 5 cycles? The PRP is 100 microseconds.
a) 1%
b) 100%
c) 5%
d) 10%
a) 1%
56
If you want to be able to recieve echoes from a depth of 10 cm, how long should your PRP be?
a) 130 microseconds
b) 65 microseconds
c) 2 seconds
d) 0.5 seconds
a) 130 microseconds
57
What is the wavelength in fat for a 5 MHz ultrasonic wave?
a) 0.14 cm
b) .014 mm
c) 0.29 cm
d) 0.29 mm
d) 0.29 mm
58
What is the period for a 5 MHz ultrasonic wave?
0.2 microseconds
59
What term describes the region of increased molecular density induced by sound propagation in a medium?
a) compression
b) focal
c) fresnel
d) rarefaction
a) compression
60
What is the compression zone?
region of high particle density
61
What is the rarefaction zone?
region of low particle density
62
What term describes the distance between compression zones?
a) acoustic velociy
b) frequency
c) period
d) wavelength
d) wavelength
63
What term describes the distance of one cycle for a wave?
wavelength
64
In which material does a 10 MHz sound wave have the longest wavelength?
a) bone
b) fat
c) muscle
d) air
a) bone
material with the greatest acoustic velocity has the greatest wavelength
65
What characterizes the elasticity of a medium?
a) fractional change is shape from an applied force
b) return to orignial shape after removal of applied force
c) high particle velocity during propagation
d) low particle velocity during propagation
b) return to original shape after removal of applied force
66
What denotes a longitudinal wave?
a) particle motion is along the direction of propagation
b) particle motion is perpendicular to the direction of propagation
c) wavelength over 1 mm
d) wavelength over 1 cm
a) particle motion is along the direction of propagation
67
What describes a transverse wave?
a) particle motion is along the direction of propagation
b) particle motion is perpendicular to the direction of propagation
c) wavelength over 1 mm
d) wavelength over 1 cm
b) particle motion is perpendicular to the direction of propagation
68
Which type of wave exhibits particle motion along the direction of propagation?
a) longitudinal
b) sheer
c) transverse
d) light
a) longitudinal
69
What term describes the rate of flow energy over a small area?
a) compression
b) intensity
c) pressure
d) frequency
b) intensity
70
What is the frequency range for human hearing?
a) 20-20,000 Hz
b) 20-20,000 kHz
c) 20-1500 Hz
d) 20-20,000 kHz
a) 20-20,000 Hz
71
Which acoustic variable is equal to acoustic velocity divided by the frequency?
a) intensity
b) pressure
c) period
d) wavelength
d) wavelength
72
Which medium type is likely to have the slowest acoustic velocity?
a) gas
b) liquid
c) tissue
d) metal
a) gas
73
Which tissue type has the lowest rate of attenuation?
a) blood
b) bone
c) fat
d) soft tissue
a) blood
74
Which acoustic parameter determines the intensity reflection coefficient?
a) acoustic impedance
b) acoustic velocity
c) frequency
d) intensity
a) acoustic impedance
75
Which frequency of the incident sound wave produces the strongest echo for a large interface composed of soft tissue and fat? Assume each incident wave has eaual intencity.
a) 2 MHz
b) 4 MHz
c) 6 MHz
d) independent of frequency
d) independent of frequency
76
How does frequency affect the rate of absorption in soft tissue?
a) directly
b) indirectly
c) threshold at 5 MHz
d) no effect
a) directly
77
What property of the medium affects acoustic impedance?
a) density
b) thickness
c) viscosity
d) specific heat
a) density
78
What is the effect on echo intensity if the media that compose the interface are reversed?
a) increased
b) decreased
c) depends on frequency
d) no effect
d) no effect
79
What does Snell's Law predict?
a) beam direction transmitted through an interface
b) frequency of wave transmitted through an interface
c) rate of absorption
d) rate of divergence from a source
a) beam direction transmitted through an interface
80
What factor is explicitly stated in Snell's Law?
a) acoustic velocity
b) acoustic impedance
c) frequency
d) intensity
a) acoustic velocity
81
If the acoustic velocity in the first medium is greater than that in the second, what is the effect on the angle of transmission?
a) bend toward normal
b) bend away from normal
c) no change in direction
d) total reflection occurs
a) bend toward normal
82
Which interaction describes the algebraic summation of waves?
a) absorption
b) reflection
c) refreaction
d) interference
d) interference
83
Which is a characteristic of destructive interference?
a) increased amplitude
b) decreased amplitude
c) increased acoustic velocity
d) decreased acoustic velocity
b) decreased amplitude
84
Which is most likely to produce scatter?
a) RBC
b) skull
c) diaphragm
d) distilled water
a) RBC
85
If the reflected intensity is 50% of the incident intensity for a 3 MHz sound wave, what is the percent of transmitted intensity? Assume specular reflection.
50
86
What effect does divergence have on beam intensity as the sound wave radiates outward from a small source?
a) decreased
b) increased
c) depends on the medium
d) no effect
a) decreased
87
What is the effect on the instantaneous intensity if the pressure decreases by a factor of 2?
a) decreased by a factor of 2
b) decreased by a factor of 4
c) decreased by a factor of 1.4
d) no effect
b) decreased by a factor of 4
88
What effects the rate of loss of beam intensity as the pulsed wave propagates through tissue?
a) PZT crystal diameter
b) beam width
c) frequency
d) pulse duration
c) frequency
89
What affects the intensity loss for a pulsed wave that ahs traveled from the transducer to the specular reflector at a depth of 5cm?
a) PZT crystal diameter
b) beam width
c) frequency
d) pulse duration
c) frequency
90
What affects the intensity loss for a pulsed wave that ahs traveled from the transducer to the specular reflector at a depth of 5cm?
a) PZT cyrstal diameter
b) beam width
c) medium type
d) pulse duration
c) medium type
91
What is the duty factor for a pulsed wave transducer used in imagaing?
a) 0.01
b) 0.10
c) 0.50
d) 0.99
a) 0.01
92
What is the duty factor for a continuous wave transducer used in Doppler?
a) 0.01
b) 0.10
c) 0.50
d) 1.0
d) 1.0
93
What term describes the fraction of time that the transducer is actively generating ultrasound waves?
a) derating factor
b) duty factor
c) PRP
d) Q value
b) duty factor
94
Which statement describes intensity measurements using the decibel nomenclature?
a) based on a logarithmic scale
b) measure of absolute intensity
c) limited to intensity values that are less than the reference value
d) all of the above
a) based on a logarithmic sale
95
The intensity loss from the surface to point 1 is 5 dB. The intensity loss from point 1 to point 2 is 3 dB. What is the total loss from the surface to point 2?
8 dB
96
Which equation symbolizes intensity change in dB?
a) 10 exp (I/Io)
b) 10 log I/Io)
c) Io(1/2n)
d) p2/pc
b) 10 log (I/Io)
97
What is the attenuation coefficient for soft tissue?
a) 0.3 dB/MHz/cm
b) 0.7 dB/MHz/cm
c) 0.3 dB/MHz/mm
d) 0.7 dB/MHz/mm
b) 0.7 dB/MHz/cm
98
What is the time duration for averaging of the SPPA intensity?
a) one cycle
b) transmitted pulse
c) PRP
d) one frame
b) transmitted pulse
99
What is the time duration for averaging of the SPTP intensity?
a) one cycle
b) transmitted pulse
c) PRP
d) instantaneous (no duration)
d) none
100
What is the spatial extent for averaging of the SATA intensity?
a) wavelength
b) beam width
c) propagation speed
d) focal zone
b) beam width
101
Which intensity descriptor has the lowest numerical value?
a) SPTP
b) SPTA
c) SAPA
d) SATA
a) SPTP
102
What is power?
a) energy per time
b) energy per time per area
c) intensity per area
d) intensity per time
a) energy per time
103
What are the units for the attenuation coeefficient?
a) dB/(cm-s)
b) dB/ (cm-MHz)
c) mW/cm2
d) mW
b) dB/cm/MHz
104
What is the wavelength in soft tissues for a 10 MHz ultrasound wave?
a) 0.15 cm
b) 0.30 cm
c) 0.15 mm
d) 0.30 mm
c) 0.15 mm
105
What term decribes the number of pressure oscillations per unit time?
a) acoustic velocity
b) period
c) frequency
d) wavelength
c) frequency
106
What term describes the time of one cycle for a wave?
a) acoustic velocity
b) period
c) frequency
d) wavelength
b) period
107
In which material does a 10 MHz sound wave have the shortest wavelength?
a) bone
b) muscle
c) soft tissue
d) lung
d) lung
108
What characterizes the compressibility of a medium?
a) fractional change in shape from an applied force
b) return to original shape after removal of applied force
c) high particle velocity during propagation
d) low particle velocity during propagation
a) fractional change in shape from an applied force
109
What is the lower frquency limit for ultrasound?
20,000 Hz
110
What parameter is a measure of resistance to sound passing through a medium?
a) acoustic impedance
b) bulk modulus
c) dielectric constant
d) compressibility
a) acoustic impedance
111
Which of the following interactions with matter is independent of frequency?
a) absorption
b) attenuation
c) specular reflection
d) scattering
c) specular reflection
112
What information regarding the reflector is obtained by echo ranging principle?
a) depth
b) physical size
c) density
d) velocity
a) depth
113
What affects the magnitude of the scattered ultrasound intensity?
a) frequency
b) number of scatterers
c) size of scatterers
d) all of the above
d) all of the above
114
Attenuation in a medium depends on all of the following EXCEPT:
a) acoustic velocity
b) absorption
c) scattering
d) distance traveled
a) acoustic velocity
115
Why is high frequency problematic in imaging?
a) alters the acoustic impedance
b) alters the acoustic velocity
c) loss of penetration depth
d) reduced reflection coefficient
c) loss of penetration depth
116
If ultrasound intensity is increased by a factor of 100, what is the gain in dB?
a) 2 dB
b) 10 dB
c) 20 dB
d) 100 dB
c) 20 dB
117
After a 6 MHz ultrasound beam passes through 5 cm of soft tissue, what is the intensity loss for an ultrasound beam? Assume att. coeff. is 0.5 dB/cm/MHz.
a) 4 dB
b) 5 dB
c) 15 dB
d) 30 dB
c) 15 dB
118
Which intensity descriptor has the lowest numerical value?
a) SPTP
b) SPTA
c) SAPA
d) SATA
d) SATA
119
Four waves have PRP as listed below. Which of the following four waves has the lowest PRF?
a) 8s
b) 80 microseconds
c) 8000 nanoseconds
d) 800 miliseconds
a) 8s
120
True/False?
| Two waves can have identical PRFs, even if their PRPs are different.
False
121
True/False?
| Two waves can have identical PRFs, even if their frequencies are different.
True
122
True/False?
| PRF and PRP are determined only by the imaging depth.
True
123
Which of the following terms does not belong with the others?
a) high duty factor
b) shallow imaging
c) low PRF
d) short PRP
c) low PRF
124
All of the following correctly describe an imaging transducer except:
a) high sensitivity
b) low Q
c) wide bandwidth
d) damped
a) high sensitivity
125
In an imaging transducer, what is the purpose of attaching the backing material to the PZT?
a) increase the bandwidth
b) decrease the Q factor
c) improve image quality
d) decrease the transducer's sensitivity
c) improve image quality
126
The distance that a pulse occupies in space from the start to the end of a pulse is:
a) SPL
b) pulse duration
c) duty factor
d) PRP
a) SPL
127
SPL is:
a) directly proportional to the number of cycles in a pulse
b) directly proportional to wavelength
c) inversely proportional to frequency
d) all of the above
d) all of the above
128
Which of these four values for PRF would have the longest PRP?
a) 1 kHz
b) 2 kHz
c) 6 Hz
d) 4,000 Hz
c) 6 Hz
129
What is the duty factor for an ultrasound pulse at 5 MHz that contains five cycles? The PRP is 100 microseconds.
a) 1%
b) 100%
c) 5%
d) 10%
a) 1%
130
If you want to be able to receive echoes from a depth of 10 cm, how long should your PRP be?
a) 0.5 s
b) 2s
c) 65 micros
d) 130 micros
d) 130 micros
131
The piezoelectric effect is found in crystalline materials that contain __.
a) water
b) dipoles
c) high density
d) fuzzy edges
b) dipoles
132
If you apply a short voltage pulse to a PZT element, what happens?
a) you will feel an electric shock
b) it disintegrates
c) mechanical motion
d) it glows
c) mechanical motion
133
If you want a tuning fork to vibrate at a certain frequency, say middle C, how many times do you have to strike it?
a) 1
b) twice
c) continuously
d) never
a) 1
134
What determines the natural frequency of a PZT element?
a) thickness
b) width
c) acoustic impedance
d) intensity
a) thickness
135
What is the purpose of the backing material in a transducer?
a) shorten duration of the sound pulse
b) reduce the intensity of the sound pulse
c) lengthen the sound pulse
d) add harmonics to the sound pulse
a) shorten duration of the sound pulse
136
Bandwidth refers to __.
a) the size of the wire from the ultrasound unit to transducer
b) the width of an individual scan line
c) the range of frequencies in the sound pulse
d) the range of intensites in the sound pulse
c) the range of frequencies in the sound pulse
137
Typical imaging transducers should have a Q value of __.
a) 2
b) 10
c) 100
d) 0.5
a) 2
138
If you set the ultrasound system to 6 MHz, what frequency (lies) will be transmitted into the patient?
a) 3 MHz
b) a range of frequencies from 5-7 MHz (if the Bw=2MHz)
c) 12 MHz
d) a range of frequencies from 6 to 12 MHz
b) a range of frequencies from 5-7 MHz (if the Bw=2MHz)
139
What is another name for the near field (the zone before the focal zone)?
a) fresnel
b) fraunhofer
c) far
d) focal
a) fresnel
140
If the time between transmission and reception of the echo is 130 micros, how far is the reflector from the transducer?
a) 2cm
b) 8cm
c) 4cm
d) 10cm
d) 10cm
141
What adjustments will improve axial resolution by decreasing the SPL?
a) increase the frame rate
b) increase the output power
c) increase gain
d) increase frequency
d) increase frequency
142
What is the range of echo intensities present if we set our dynamic range at 60 dB?
a) 1,000,000
b) 100,00
c) 10,000
d) 1,000
a) 1,000,000
143
An ultrasonic pulse has a PRP of 1.2 msec, an SPL of 2.0mm, and a wavelength of 0.4mm. What is the axial res?
a) 2mm
b) 1mm
c) 0.4mm
d) 1.8mm
b)1mm
144
How thick is the active element of a 3MHz pulsed wave transducer?
a) 1.54mm
b) 0.51mm
c) half the wavelength of the sound wave in the PZT
d) 1/4 the wavelength of the sound in the matching layer
c) half the wavelength of the sound wave in the PZT
145
What is the purpose of the backing material?
a) reduce SPL
b) reduce transmitted bandwidth
c) increase the transmitted frequency
d) increase the PRF
a) reduce SPL
146
Where is the matching layer?
a) next to the backing layer
b) contiguous with the RF shield
c) next to the crystal
d) at the cable connection to the transducer
c) next to the crystal
147
What is the usual thickness of the matching layer?
a) one wavelength
b) 1/2 wavelength
c) 1/4 wavelength
d) twice wavelength
c) 1/4 wavelength
148
What determines the maximum PRF?
a) scan range
b) center frequency
c) transmit power
d) crystal material
a) scan range
149
What is the pulse duration?
a) length in mm of the transmitted pulse
b) time of the pulse/listen cycle
c) length of one cycle in the transmitted pulse
d) time between consecutive transmitted pulses
e) none of the above
e) none of the above
150
What is the Q-value of a transducer?
a) bandwidth divided by the center frequency
b) maximum transmit power
c) inverse of the fractional bandwidth
d) ratio of axial resolution to later resolution
c) inverse of the fractional bandwidth
151
What is the PRP?
a) time of the transmitted pulse
b) time of the pulse/listen cycle
c) time of one cycle in the transmitted pulse
d) time to receive echo from the depth of the scan range
b) time of the pulse/listen cycle
152
What piezoelectric material is used in the transducer?
a) carbon
b) PZT
c) cesium iodide
d) graphite in epoxy
b) PZT
153
What is the design goal of the backing material?
a) acoustic impedance similiar to that of crystal
b) reduce the transmitted bandwidth
c) increase the transmitted frequency
d) acoustic velocity similiar to that of crystal
a) acoustic impedance similiar to that of crystal
154
What factors determine the SPL?
a) number of cycles and wavelength
b) pulse duration and PRF
c) frequency and PRF
d) wavelength and period of wave
a) number of cycles and wavelength
155
What is the Q value of a continuous wave transducer?
a) 2
b) 100
c) 250
d) 700
d) 700
156
What is a characteristic of rapidly damped, pulsed wave?
a) broad bandwidth
b) high Q value
c) high frequency greater than 5 MHz
d) short focal zone
a) broad bandwidth
157
What is a characteristic of transducers with composite ceramic elements compared with solid piezoelectric elements?
a) high acoustic impedance
b) broad bandwidth
c) formed as thin membranes
d) low sensitivity
b) broad bandwidth
158
What is a characteristic of transducers with composite ceramic elements compared with solid piezoelectric elements?
a) low acoustic impedance
b) narrow bandwidth
c) formed as thin membranes
d) low sensitivity
a) low acoustic impedance
159
What is the function of a transducer?
a) creates magnetic fields
b) converts energy from one form to another
c) measures acoustic impedance
d) generates x-rays
b) converts energy from one form to another
160
What is the effect of voltage applied to a piezoelectric element?
a) emits x-rays
b) changes thickness
c) changes area of radiating surface
d) emits light
b) changes thickness
161
Which operating frequency will have the thickest crystal?
a) 2 MHz
b) 4 MHz
c) 6 MHz
d) 8 MHz
a) 2 MHz
162
Which of the following statements is true about the SPL?
a) as the number of cycles in the pulse decreases, the SPL decreases
b) as the frequency increases, the SPL increases
c) as the SPL increases, the axial resolution is improved
d) SPL is shortened by damping
d) SPL is shortened by damping
163
Which adjustment can improve the axial resolution?
a) increase the PRF
b) increase the pulse duration
c) increase the operating frequency
d) increase the power
c) increase the operating frequency
164
What is the best estimate of axial resolution?
a) 1/2 the beam width
b) 1/2 the SPL
c) equal to the beam width
d) equal to the SPL
b) 1/2 the SPL
165
Where within the scan range is axial resolution superior?
a) near the transducer
b) in the focal zone
c) at the scan range limit
d) independent of depth
d) independent of depth
166
Lateral resolution is the ability to resolve objects __.
a) along the propagation path
b) with similar reflectivites
c) perpendicular to the propagation path
d) within the focal zone
c) perpendicular to the propagation path
167
What is the best predictor of lateral resolution?
a) beam width
b) SPL
c) PRF
d) frequency
a) beam width
168
Which modification increases the near-field depth for a nonfocused, single-element transducer?
a) decrease the crystal diameter
b) increase the center frequency
c) increase the wavelength
d) decrease the thickness of the matching layer
b) increase the center frequency
169
Which modification increases the near-field depth for a nonfocused, single-element transducer?
a) increase the crystal diameter
b) decrease the center frequency
c) increase the wavelength
d) decrease the thickness of the matching layer
a) increase the crystal diameter
170
Which modification increases the angle of divergence in the far field for a nonfocused, single-element transducer?
a) decrease the crystal diameter
b) increase the center frequency
c) decrease the wavelength
d) increase damping of ringing crystal
a) decrease the crystal diameter
171
What term describes the ultrasonic beam near the transducer with relatively constant beam width?
a) compression zone
b) focal zone
c) fraunhofer zone
d) near zone
d) near field
172
What does not affect the beam width in the focal zone of a single-element transducer?
a) aperature
b) frequency
c) focal length
d) SPL
d) SPL
173
What is the purpose of focusing?
a) reduce the SPL
b) reduce the beam width
c) increase the center frequency
d) increase the bandwidth
b) reduce the beam width
174
What is the depth of field?
a) distance to the focal point
b) length of the focal zone
c) depth of the near field
d) width of the near field
b) length of the focal zone
175
What determines the degree of focusing for a single-element transducer?
a) acoustic impedance of the matching layer
b) crystal thickness
c) curvature of the crystal
d) excitation voltage
c) curvature of the crystal
176
What is the smallest distance between reflectors that generate two distinct echoes from a two-cycle, 5 MHz pulse?
a) 0.15mm
b) 0.31mm
c) 0.62mm
d) 1.24mm
b) 0.31mm
177
How is attenuation loss along the path corrected in A-mode?
a) signal level adjusted during integration
b) application of reject
c) TGC
d) no correlation is possible
c) TGC
178
What is the beam width of an unfocused transducer at a distance of twice the near field depth?
a) twice the transducer diameter
b) 1.4 times the focal width
c) the same as the transducer diameter
d) need the F# to calculate this width
c) the same as the transducer diameter
179
What is the piezoelectric effect?
a) conversion of acoustic energy to/from electrical energy
b) transfer of acoustic energy to heat by the attenuating medium
c) scattering of acoustic energy in a radial symmetric pattern
d) reduction in ultrasound frequency by the absorbing medium
a) conversion of acoustic energy to/from electrical energy
180
What is the purpose of the matching layer?
a) increase the PRF
b) reduce the transmitted bandwidth
c) increase the transmitted frequency
d) enhance transmission into the patient
d) enhance transmission into the patient
181
What is the SPL for a 3 cycle pulse if the frequency is 5 MHz?
a) 0.15mm
b) 0.31mm
c) 0.62mm
d) 0.92mm
d) 0.92mm
182
What is the Q-value of a transducer?
a) maximum transmit power
b) ratio of center frequency to bandwidth
c) maximum scan range in tissue
d) ratio of axial resolution to later resolution
b) ratio of center frequency to bandwidth
183
If a 5MHz wave is generated in the piezoelectric crystal, what is the frequency when the wave enters the patient?
a) 2.5MHz
b) 4 MHz
c) 5 MHz
d) 10 MHz
c) 5 MHz
184
Which operating frequency will have the thinnest crystal?
a) 2 MHz
b) 4 MHz
c) 6 MHz
d) 8 MHz
d) 8 MHz
185
Which of the following statements is true about the SPL?
a) as the number of cycles in the pulse decreases, the SPL increases
b) as the frequency increases, the SPL decreases
c) as the SPL increases, the axial resolution is improved
d) SPL is increased by damping
b) as the frequency increases, the SPL decreases
186
Axial resolution is the ability to resolve objects __.
a) along the propagation path
b) with similiar reflectivities
c) perpendicular to the propagation path
d) within the focal zone
a) along the propagation path
187
True/False?
| Many frequencies are present in short pulses.
True
188
What are side lobes?
a) secondary ultrasound beams offset from the main beam
b) multiple echoes produced during specular reflection
c) energy transmitted at twice the fundamental frequency
d) interference pattern from multiple, small scatterers
a) secondary ultrasound beams offset from the main beam
189
What is the focal length?
a) distance from the transducer to the focal point
b) width at the focal depth
c) depth of the far field
d) width of the near field
a) distance from the transducer to the focal point
190
What is your estimate for the range resolution for a 2 cycle, 10 MHz pulse?
a) 0.15mm
b) 0.31mm
c) 0.62mm
d) 1.24mm
a) 0.15mm
191
Which of the following transducers has the best range resolution in the far field?
a) low frequency, large diameter
b) high frequency, large diameter
c) low frequency, small diameter
d) high frequency, small diameter
b) high frequency, large diameter
192
What happens to the pulse duration when a sonographer decreases the maximum depth?
a) increases
b) decreases
c) remains the same
d) cannot be determined
c) remains the same
193
The acoustic impedance of the PZT is 35 MRayl and soft tissue is 1.6 MRayl. What is an appropriate acoustic impedance for the matching layer?
a) 1.6 MRayl
b) 2.0 MRayl
c) 7.5 MRayl
d) 35 MRayl
c) 7.5 MRayl
194
At which depth is axial resolution?
a) near the transducer
b) in the focal zone
c) at the scan range limit
d) independent of depth
d) independent of depth
195
Which adjustment can improve the transverse resolution?
a) select a lower frequency
b) move the focal zone to the area of interest
c) select a smaller diameter transducer
d) increase the power
b) move the focal zone to the area of interest
196
The PRF of ultrasound produced by a transducer typical of diagnostic imaging systems ___.
a) can be changed by the sonographer
b) depends on the medium through which the sound travels
c) is unchanged as long as the same ultrasound system is used
d) has nothing to do with clinical imaging
a) can be changed by the sonographer
197
Which of the following explains why a sound beam created by a disc-shaped crystal is hour-glass shaped?
a) Bernouli's principle
b) Fraunhofer's law
c) Hendrick's theory
d) Huygen's principle
d) Huygens principle
198
What does the brightness level for each pixel in the ultrasound image correspond to?
a) attenuation
b) frequency
c) echo strength
d) delay time
c) echo strength
199
One of the drawbacks of static B-mode imaging is __.
a) small field of view
b) single depth focusing
c) border definition
d) expensive transducers
single depth focusing
200
True/False?
| Static B-mode systems are commonly using in patient care.
False
201
What device is necessary to retain the spatial location of signals in the static B-mode?
a) analog to digital converter
b) log amplifier
c) monitor
d) scan converter
d) scan converter
202
Which imaging modality places time of flight information on the x-axis and echo amplitude on the y-axis?
a) B-mode
b) color doppler
c) M-mode
d) A-mode
d) A-mode
203
Which imaging modality technique usually displays a single jagged line of varying heights?
a) M-mode
b) b-mode
c) c-mode
d) a-mode
d) a-mode
204
How is data stored from one scan line to the next in a-mode scanning?
a) in the image matrix
b) digital scan converter
c) analog to digital converter
d) data is not stored
d) data is not scored
205
Which imaging mode accurately displays reflector depth?
a) I-mode
b) c-mode
c) a-mode
d) L-mode
c) a-mode
206
What is shown in the A-mode display of a single reflector?
a) signal level of reflector versus depth
b) physical size of the reflector versus depth
c) movement of the reflector with time
d) variation in signal level with time
a) signal level of reflector versus depth
207
How many lines of sight compose the a-mode display?
a) 0
b) 1
c) 2
d) 150
b) 1
208
How often is the a-mode display refreshed with new scan data?
a) once every second
b) at the PRF
c) at the transmitted frequency
d) each line of sight is sampled once
b) at the PRF
209
How is attenuation loss along the path corrected in a-mode?
a) signal level adjusted during integration
b) application of reject
c) TGC
d) no correction is possible
c) TGC
210
What is the minimum seperation that two reflectors are resolved in the a-mode display?
a) one half the SPL along the propagation path
b) wavelength along the propagation path
c) one half the beam width perpendicular to the propagation path
d) wavelength perpendicular to the propagation path
a) one half the SPL along the propagation path
211
What is shown in the static b-mode display of a single reflector?
a) signal level of reflector and location
b) reflector in three dimensions
c) movement of the reflector with time
d) signal level of reflector with time
a) signal level of reflector and location
212
How many lines of sight compose the static b-mode display?
a) 0
b) 1
c) 2
d) 150
d) 150
213
How is echo strength depicted in the static b-mode display of a single reflector?
a) height of peak
b) brightness of dot
c) size of dot
d) displacement of dot
b) brightness of dot
214
What device is necessary to retain the spatial location of signals in the static b-mode?
a) analog to digital converter
b) log amplifier
c) scan converter
d) monitor
c) scan converter
215
What device is necessary to retain the spatial location of signals in the static b-mode?
a) analog to digital converter
b) log amplifier
c) registration arm
d) monitor
c) registration arm
216
What is represented by the value stored in a pixel of the scan converter?
a) reflector size
b) reflector position
c) reflector reflectivity
d) reflector density
c) reflector reflectivity
217
What is a characteristic of static b-mode?
a) large field of view
b) good temporal resolution
c) electronic focusing
d) unrestricted transducer movement
a) large field of view
218
What is a characteristic of static b-mode?
a) very limited field of view
b) subject to motion artifacts
c) electronic focusing
d) unrestricted transducer movement
b) subject to motion artifacts
219
What is a characteristic of static b-mode?
a) very limited field of view
b) subject to motion artifacts
c) single depth mechanic focusing
d) unrestricted transducer movement
c) single depth mechanic focusing
220
What is a characteristic of static b-mode?
a) very limited field of view
b) subject to motion artifacts
c) electronic focusing
d) restricted transducer movement
d) restricted transducer movement
221
What is the makeup of a static b-mode transducer?
a) single nonfocused element
b) single focused element
c) multiple crystal array with no electronic focusing
d) multiple crystal array with electronic focusing
b) single focused element
222
How is scan data spatially registered along a scan line during b-mode scanning?
a) echo ranging
b) frequency encoding
c) directional beam scanning
d) demodulation
a) echo ranging
223
How is scan data spatially registered across the field of view during b-mode scanning?
a) echo ranging
b) frequency encoding
c) directional beam scanning
d) demodulation
c) directional beam scanning
224
What is a common frame rate during b-mode scanning of the abdomen?
a) 1-2 frames per sec
b) 15-20 frames per sec
c) 100-200 frames per sec
d) 4000-5000 frames per sec
b) 15-20 frames per sec
225
What is a scan line or line of sight?
a) the directed path of the ultrasound beam
b) the depth of focal zone
c) width of the field of view
d) width of the transmitted beam
a) the directed path of the ultrasound beam
226
How many scan lines compose one b-mode image?
a) 1
b) 150
c) 1000
d) 10,000
b) 150
227
Why is the registration arm not necessary in the b-mode scanner?
a) slow frame rate
b) autoscanning by crystal movement or activation
c) high PRF
d) narrow beam width
b) autoscanning by crystal movement or activation
228
What device translates the scan data to the image format in the b-mode?
a) analog to digital converter
b) computer clock speed
c) scan line density
d) width of the field of view
c) scan line density
229
What is affected by the bit depth in analog to digital conversion?
a) number of digitization steps
b) computer clock speed
c) scan line density
d) width of the field of view
a) number of digitization steps
230
What can increase the dynamic range of the signals stored in the scan converter?
a) increase matrix size
b) increased bit depth
c) increased reciever gain
d) increased monitor gray levels
b) increased bit depth
231
What is a pixel?
a) smallest component of a digital image?
b) one scan line
c) one b-mode image
d) a type of sisplay monitor
a) smallest component of a digital image
232
Where is the signal level associated with a reflector stored in the scan converter?
a) analog to digital converter
b) digital to analog converter
c) pixel
d) monitor
c) pixel
233
How is the signal level associated with a reflector spatially registered in the scan converter?
a) value of pixel in the scan converter
b) row and column of pixel in scan converter
c) recording beam orientation coordinates in scan converter
d) recording of timing gates in the scan converter
b) row and column of pixel in scan converter
234
If the scan range for a b-mode transducer is decreased from 10 cm to 5cm, what is the effect on the maximum frame rate?
a) increase by a factor 4
b) increase by a factor 2
c) remain unchanged
d) decrease by a factor 2
b) increase by a factor 2
235
If the scan range for a b-mode transducer is unchanged but scan line density is decreased by a factor of 2. what is the effect on the maximum frame rate?
a) increase by a factor 4
b) increase by a factor 2
c) remain unchanged
d) decrease by a factor 2
b) increase by a factor 2
236
Whic combination of scan range and scan line number yields the maximum frame rate?
a) scan range 10cm, 100 scan lines
b) scan range 5cm, 100 scan lines
c) scan range 10cm, 200 scan lines
d) scan range 5cm, 200 scan lines
b) scan range 5cm, 100 scan lines
237
What affects lateral resolution in the b-mode image?
a) beam width
b) SPL
c) gray scale map
d) frame rate
a) beam width
238
What affects lateral resolution in the b-mode image?
a) range gate
b) SPL
c) gray scale map
d) number of scan lines
d) number of scan lines
239
What determines the field of view of the transducer?
a) frequency
b) transmit power
c) PRF
d) directional beam scanning
d) directional beam scanning
240
Which matrix size has the potential to provide the best spatial resolution?
a) 350x750
b) 480x640
c) 600x800
d) 720x960
d) 720x960
241
What determines temporal resolution?
a) beam width
b) SPL
c) frame rate
d) degree of focusing
c) frame rate
242
Which of the following is best described as an analog number?
a) the number of stars in the sky
b) the number of tires on a car
c) the number of people in a room
d) the weight of a person
d) the weight of a person
243
What happens to a digital image when the pixel density decreases?
a) spatial detail is degraded
b) temporal resolution increases
c) the field of view decreases
d) there are less shades of grey
a) spatial detail is degraded
244
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 determine
b) system b
245
What is the smallest part of a digital picture called?
a) pixel
b) bit
c) byte
d) fractal
a) pixel
246
What is the smalled amount of digital storage called?
a) pixel
b) bit
c) byte
d) fractal
b) bit
247
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 determine
b) system b
248
How can the accuracy of the digitization of the analog signal from a detector be imporved?
a) increase the bit depth
b) using a higher capacity memory
c) changing the clock frequency
d) increasing the voltage of the analog signal
a) increasing the bit depth
249
How many different numerical combinations of 0s and 1s can be represented by a byte (8 bits)?
a) 8
b) 16
c) 256
d) 1024
c) 256
250
What configuration name is given to a computer with high resolution monitors used for image interpretation?
a) ROM
b) RAID
c) PACS workstation
d) Server
c) PACS workstation
251
How is the signal level associated with a reflector spatially registered in the scan converter?
a) value of pixel in the scan converter
b) row and column of pixel in scan converter matrix
c) recording beam orientation coordinates in scan converter
d) recording of timing gates in the scan converter
b) row and column of pixel in scan converter matrix
252
How is the signal level associated with a reflector spatially registered in the scan converter?
a) value of pixel in the scan converter
b) row and column of pixel in scan converter matrix
c) recording beam orientation coordinates in scan converter
d) recording of timing gates in the scan converter
b) row and column of pixel in scan converter matrix
253
With a-mode, what parameter is displayed on the x-axis and y-axis, respectively?
a) intensity and time
b) depth and time
c) time of flight and intensity
d) voltage and intensity
c) time of flight and intensity
254
What is shown in the a-mode display of a single reflector?
a) signal level of reflector versus depth
b) physical size of the reflector versus depth
c) movement of the reflector with time
d) variation in voltage with time
a) signal level of reflector versus depth
255
With static b-mode, which axis is related to the signal intensity?
a) x-axis
b) y axis
c) z axis
d) none of the above
c) z axis
256
Which factor affects the acoustic velocity in a medium?
a) density of the medium
b) cross sectional area of ultrasound beam
c) wavelength
d) frequency
a) density of the medium
257
If the acoustic velocity in the first medium is less than that in the second, what is the effect on the angle of transmission?
a) bend toward normal
b) bend away from normal
c) no change in direction
d) total reflection occurs
b) bend away from normal
258
What is the expected axial resolution for a 2.5 cycle pulse if the frequency is 5 MHz?
a) 0.12mm
b) 0.24mm
c) 0.39mm
d) 0.77mm
d) 0.77mm
259
Which signal processing technique attempts to correct for attenuation of the ultrasound beam along the beam path?
a) apodization
b) compression
c) gray scale mapping
d) TGC
d) TGC
260
What factor affects the ratio of echo intensity compared with transmitted intensity?
a) pulse duration
b) path length
c) transmitted intensity
d) PRF
b) path length
261
What term describes the region of increased molecular density induced by sound propagation in a medium?
a) compression
b) focal
c) fresnel
d) rarefaction
a) compression
262
What term describes the number of pressure oscillations per unit of time?
a) acoustic velocity
b) frequency
c) period
d) wavelength
b) frequency
263
In which material does a 10 MHz sound wave have the longest wavelength?
a) bone
b) fat
c) muscle
d) air
a) bone
264
Which term describes the reflection of ultrasound at large, smooth interfaces?
a) specular
b) diffuse
c) nonspecular
d) scattering
a) specular
265
If ultrasound intensity is reduced by a factor of 4, what is the intensity change in decibels?
6
266
What is the importance of focusing?
a) less divergence in the far field
b) extends the depth of the near field
c) reduced beam width in focal zone
d) minimizes the need for TGC
c) reduced beam width in focal zone
267
If the bandwidth is 4 MHz and the operating frequency is 8 MHz, what is the Q value?
a) 2
b) 2 MHz
c) 4
d) 6 dB
a) 2
268
Which transducer has the longest near zone?
a) 6mm diameter, 5 MHz
b) 8mm diameter, 5 MHz
c) 8mm diameter, 10 MHz
d) 6mm diameter, 10 MHz
c) 8mm diameter, 10 MHz
269
What is the focal beam width for a transducer that has an F# of 4 and is operating at 3 MHz?
a) 1.0mm
b) 1.0cm
c) 2.8mm
d) 6.2mm
c) 2.8mm
270
Which material has the highest acoustic velocity?
a) bone
b) fat
c) muscle
d) water
a) bone
271
Which is an example of a specular reflector?
a) RBC
b) liver parenchyma
c) diaphragm
d) amniotic fluid
c) diaphragm
272
An interface composed of which of the following is most likely to generate the strongest echo?
a) fat and soft tissue
b) bone and soft tissue
c) muscle and soft tissue
d) echo strength does not depend of composition of interface
d) echo strength does not depend of compostion of interface
273
If the intensity reflection coefficient is 0.25 for a 3 MHz sound wave, what is the percent of the intensity transmitted? Assume specular reflection.
a) 0
b) 25
c) 50
d) 75
d) 75
274
What affects the rate of loss of beam intensity as the pulsed wave propagates through tissue?
a) PZT diameter
b) beam width
c) frequency
d) pulse duration
c) frequency
275
What is the design goal of the matching layer?
a) increase the transmitted frequency
b) reduce the transmitted bandwidth
c) reduce acoustic impedance mismatch between the crystal and the patient
d) increase the PRF
c) reduce acoustic impedance mismatch between the crystal and the patient
276
What is the duty factor if the PRF is 1000 Hz and the pulse duration is 20 microseconds?
a) 0.1%
b) 2%
c) 10%
d) 20%
b) 2%
277
What is the typical Q-value of a pulsed wave imaging transducer?
a) 2
b) 100
c) 250
d) 700
a) 2
278
What determines the pulse duration?
a) the source of the wave
b) the medium
c) both a and b
d) neither a nor b
a) the source of the wave
279
What is the spatial extent for averaging of the SATA intensity?
a) cross section of the beam
b) peak intensity
c) one cycle
d) instantaneous
a) cross section of the beam
280
Which of the following terms does not belong with the others?
a) increased depth of view
b) decreased duty factor
c) increased PRP
d) decreased SPL
d) decreased SPL
281
Which of these lists indicates media with increasing attenuation of ultrasound?
a) water, lung, soft tissue, bone, air
b) lung, fat, muscle
c) lung, air, soft tissue, bone
d) water, blood, fat, muscle, bone, air
d) water, blood, fat, muscle, bone, air
282
Which of these lists indicates media with increasing attenuation of ultrasound?
a) water, lung, soft tissue, bone, air
b) lung, fat, muscle
c) lung, air, soft tissue, bone
d) water, blood, fat, muscle, bone, air
d) water, blood, fat, muscle, bone, air
283
Which component of an ultrasound system exposes the patient to the greatest risk?
a) high voltage display tube
b) transducer
c) spark autoregulator
d) beam former
e) pulser
b) transducer
