Ch. 1 Review Questions
All of the following are true of power except: a. as amplitude increases, power remains the same b. power is proportional to amplitude squared c. intensity is proportional to power d. power is measured in milliwatts
a. power is proportional to amplitude squared, so power decreases as amplitude decreases
An increase in PRF would lead to: a. an increase in DF b. a decrease in PD c. an increase in the number of cycles d. a decrease in resolution
a. DF DF=PD/PRP PRP is inversely related to PRF
What time is defined as the beginning of one pulse to the beginning of the next pulse and, therefore, includes both the "on" and "off" time? a. PRP b. PD c. DF d. PRF
a. PRP
As a sound wave travels through the human body, the intensity of the sound wave decreases as a result of: a. attenuation b. elevational resolution c. Huygen's principle d. refraction
a. attenuation
All of the following are true of wavelength except: a. it is determined by both the medium and the sound source b. it is equal to the period divided by the frequency c. it is inversely related to frequency d. it is directly related to period
b. wavelength = propagation speed / frequency
The typical range of frequency for diagnostic ultrasound imaging is: a. 20 to 20,000 Hz b. 1 to 20 MHz c. 2 to 15 kHz d. 12 to 100 MHz
b. 1 to 20 MHz
The DF for CW ultrasound is: a. 1.0% b. 100% c. 20,000 Hz d. 8 Pa
b. 100%
What is the total amount of attenuation that occurs if a 6.0-MHz sound beam travels through 4 cm of soft tissue? a. 24 dB b. 12 dB c. 6 dB d. 1.5 dB
b. 12 dB Attenuation = (f/2) x path length
The major component of attenuation is: a. scatter b. absorption c. transmission d. refraction
b. absorption
Which of the following would have the highest propagation speed? a. air b. bone c. soft tissue d. water
b. bone
The prefix "centi" denotes: a. thousandths b. hundredths c. millions d. hundreds
b. hundredths
The percentage of time that the ultrasound system is producing pulses of ultrasound describes the: a. PRP b. PD c. DF d. PRF
c. DF
Which of the following is defined as the number of ultrasound pulses emitted in 1 second? a. PRP b. DF c. PRF d. SPL
c. PRF
Adding damping to the transducer improves which type of resolution? a. transverse resolution b. temporal resolution c. axial resolution d. elevational resolution
c. axial resolution axial is improved when the pulse is shorter
As imaging depth increases, the PRF must: a. not change b. increase c. decrease d. PRF does not relate to imaging depth
c. decrease depth and PRF are inversely related
The inertia of the medium describes its: a. attenuation characteristics b. stiffness c. density d. elasticity
c. density
What term is defined as "the power of a wave divided by the area over which the power is distributed?" a. amplitude b. power c. intensity d. absorption
c. intensity
In clinical imaging, the wavelength typically measures between: a. 1 and 10 Hz b. 1540 and 2000 m/s c. 0 and 1 d. 0.1 to 0.8 mm
d. 0.1 to 0.8 mm
Which of the following is considered the speed of sound in soft tissue? a. 1.54 m/s b. 0.77 m/s c. 100 mW/cm^2 d. 1540 m/s
d. 1540 m/s
Which of the following is defined as only the active time? a. DF b. PRF c. Period d. PD
d. PD
Which of the following describes the amount of refraction that occurs at an interface? a. Bernoulli's law b. Poiseuille's law c. Law of reflection d. Snell's law
d. Snell's law
The maximum value or minimum value of an acoustic variable minus the equilibrium value of that variable describes the: a. power b. intensity c. DF d. amplitude
d. amplitude
What is the change in power if the amplitude triples? a. it doubles b. it triples c. it quadruples d. it increases nine times
d. it increases nine times power is proportional to amplitude squared
Areas of high pressure and density are referred to as: a. compressions b. rarefactions c. diffractions d. refractions
a. compressions
Which of the following is determined by the sound source only? a. frequency b. wavelength c. SPL d. propagation speed
a. frequency
Density and propagation speed are: a. inversely related b. directly related c. directly proportional d. unrelated
a. inversely related
Density is typically measured in: a. kilograms per centimeter cubed b. millimeters c. Watts per square centimeter d. pascals
a. kilograms per centimeter cubed
Which of the following is an approximate unit of measurement for propagation speed? a. millimeters per microsecond (mm/us) b. watts per square centimeter (W/cm^2) c. microseconds (ms) d. kilohertz (kHz)
a. millimeters per microsecond (mm/us)
Micro denotes: a. millionth b. hundredth c. million d. billionth
a. millionth
The attenuation coefficient in soft tissue is equal to: a. one-half of the operating frequency b. double the operating frequency c. frequency times path length d. the total decibels
a. one-half of the operating frequency
Damping of the sound beam: a. reduces the SPL b. increases the SPL c. increases the PD d. has no impact on SPL or PD
a. reduces the SPL damping decreases the number of cycles in a pulse
Which of the following is described as the ability of an object to resist compression and relates to the hardness of a medium? a. stiffness b. density c. pressure d. inertia
a. stiffness
If the angle of incidence is 40', what is the angle of transmission at the interface if medium 1 has a propagation speed of 1320 m/s and medium 2 has a propagation speed of 1700 m/s? a. 0' b. >40' c. <40' d. cannot tell the angle of transmission
b. >40'
As imaging depth increases, PRP: a. remains constant b. increases c. decreases d. doubles
b. increases Depth and PRP are directly related
What is the change in intensity if the power decreases by half? a. intensity doubles b. intensity is halved c. intensity is one-fourth d. intensity does not change
b. intensity is halved intensity and power are directly related
Pressure is typically expressed in: a. frequency b. pascals c. decibels d. kilograms per centimeter cubed
b. pascals
What are the units for pressure? a. feet, inches, centimeters, or miles b. pascals or pounds per square inch c. kilograms per centimeter cubed d. hertz, kilohertz, or megahertz
b. pascals or pounds per square inch
If only the density of a medium is increased, then the: a. propagation speed will increase b. propagation speed will decrease c. propagation speed will stay the same d. none of the above
b. propagation speed will decrease density and propagation speed are inversely related
The portion of the sound beam where the molecules are farther apart describes an area of: a. compression b. rarefaction c. refraction d. amplitude
b. rarefaction
Which of the following requires an oblique interface and a propagation speed mismatch? a. reflection b. refraction c. normal incidence d. damping
b. refraction
All of the following relate to the strength of the sound wave except: a. amplitude b. wavelength c. intensity d. power
b. wavelength
Which of the following would be considered ultrasonic? a. 10 Hz b. 18 kHz c. 0.5 MHz d. 200 Hz
c. 0.5 MHz
Transducers have material within them that, when electronically stimulated, produces ultrasound waves. This is most likely some form of: a. tungsten acetate b. dilithium zirconium c. lead zirconate titanate d. barium sulfate
c. lead zirconate titanate
SPL can be calculated by: a. multiplying the number of cycles by the frequency b. dividing the period by the frequency c. multiplying the number of cycles by the wavelength d. dividing the number of cycles by the wavelength
c. multiplying the number of cycles by the wavelength
The change in the direction of the original sound wave that occurs when sound interacts with two different tissue types that have a different propagation speed is referred to as: a. wavelength b. scattering c. refraction d. absorption
c. refraction
Which of the following would have the lowest propagation speed? a. water b. soft tissue c. bone d. lung tissue
d. lung tissue
Sound is technically a: a. transverse and longitudinal wave b. mechanical and transverse wave c. nonmechanical and pressure wave d. mechanical and longitudinal wave
d. mechanical and longitudinal wave
What are the units of DF? a. dB b. dB/cm c. Hz d. unitless
d. unitless It is a percentage of time that sound is being transmitted
Which of the following is described as the distance over which one cycle occurs? a. PD b. DF c. period d. wavelength
d. wavelength
Which of the following is determined by the sound source and medium? a. propagation speed b. frequency c. period d. wavelength
d. wavelength Wavelength is determined by frequency and propagation speed