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Which of the lines above A, B, C, or D, is most likely to be the reciprocal of frequency?
line D
Peak and Average are two of the five key words used to describe the intensities of the same wave in different ways. Which of the following statements below is correct?
peak is greater than average
Which of the following best describes line A?
pulse duration
What is 10^-6 x 10^-3?
10^-9
These intensities describe the same wave in different ways. See below.
1. SPTP
2. SATP
3. SPTA
4. SATA
true
What happens to the speed of sound in a medium when the bulk modules increases?
faster
Which of the following best describes waves D and E?
in phase, different amplitudes*
Which of the following best describes line B?
amplitude
Which of the following best describes line F?
peak to peak amplitude
True or False. Intensities may not be reported in various ways in relations to bioeffects.
false
If the intensity remains the same while the power is doubled, what happens to the beam area?
doubled
Which of the following best describes line E?
listening time
Which of the following waves will have the shortest wavelength?
high frequency traveling in a slow medium
Which of the following best describes line C?
amplitude*
Which of the following best describes waves B and C?
in phase, different amplitudes
PRF is the reciprocal of ____
Pulse repetition period (PRP)
Which of the following best describes line B?
none of the above
Which of the following best describes waves A and E?
different frequencies same amplitude
How many hertz is 3MHz?
3,000,000
Which of the following best describes line D?
wavelength
____ intensity is the highest intensity in bioeffects.
SPTP
Which of the following statements is correct regarding intensities.
SPTP is the highest intensity, and SATA is the lowest intensity.
How much bigger is a billion than a million?
1000 times
All of the following apply to intensity?
all of the above
SPTA is related to tissue cooling?
false
True or False. Intensities may not be reported in various ways with respect to time and space.
false
What of the following best describes line D?
period
Which of the following best describes line A?
spatial pulse length
Which of the following intensities is the most important for thermal bioeftects?
spatial peak, temporal average
(Intensity) Pulse is referring only to
the time the pulse exists (transmit only)
____ is the time from the start of a pulse to the end of that pulse.
pulse duration
Which of the following best describes waves A and B?
out of phase, same amplitude
____ intensity is the lowest intensity in bioeffects.
SATA
SPTA is related to tissue heating?
true
SAPA is an abbreviation for?
spatial average, pulse average
Which of the following best describes line C?
pulse repetition period
How many liters are in 80 ml of fluid?
0.080
Which of the following best describes waves A and C?
out of phase, different amplitude
Which of the following does not apply as a key word relating to intensity.
uniformity
Intensity is the relevant intensity with respect to tissue heating.
SPTA
Which of the following characteristics will create the fastest speed of sound?
low density, high stiffness
____ is the time from the start of a pulse to the start of the next pulse.
pulse repetition period*
If the frequency of sound is doubled, what happens to the wavelength?
wavelength is halved
How many milliliters are contained in a jar filled with 5 liters of fluid?
5,000
SPTA is an abbreviation for?
spatial peak, temporal average
Which of the lines above A, B, C is most likely to be determined by the source and the medium?
line B
What is 10^-6 divided by 10^-3?
10^-3
Which of the following best describes line D?
period
What is 10^-6 seconds / 10^-3 seconds?
10^-3
Reflections from a smooth reflector are considered to be?
specular reflections
Rayleigh scattering is related to
frequency
Which of the following terms does not belong with the others?
oblique
There is normal incidence between the sound wave and the boundary between media 2 and media 3. What happens at the boundary between media 2 and 3?
transmission only
True or False. Acoustic impedance density x propagation speed.
true
As the path length increases, attenuation of US in soft tissue
increases
Every 3 dB means that the intensity will?
double
-10 dB means that the intensity is reduced to ____ of its original value.
one-tenth
An ultrasound system is operating at 100% power and the power setting is 0 dB. What would the power setting be when the system is operating at 25% power?
-6 dB
A sound wave strikes a boundary at normal incidence. The impedance of the two media are identical. What percentage of the sound wave refracted?
0%
The power of a system is at 100% and this is 0 dB. The system is changed to -6 dB. What is the system's power?
25%
The relative change in a sound beam's intensity is measured in?
dB
What are the units of attenuation?
decibels
100 mW/cm2. Answer the following question based on the chart above. What does the 100 mW/cm^2 stand for?
the incident intensity of the ultrasound beam
Which of the following mathematically describes the physics of refraction?
Snell's Law
What property has units of rayls? How is it determined?
impedance
Which of the following terms best describes a reflection arising from a rough boundary?
non-specular
If the final intensity is less than the initial intensity then the gain in dB must have been (+ or -)?
negative
A drop in intensity to one-quarter of its original value is?
-6 dB
The initial intensity of a wave is 2 mW/cm^2, and there is a change of 9 dB. What is the final intensity?
16 mW/cm^2
A 3 MHz sound beam travels 10 cm, 6 cm in medium A and 4 cm in medium B. The total attenuation is 14 dB. If the sound beam attenuated 4 dB in medium A, then how much attenuation occurred in medium B?
10 dB
A sound wave with an intensity of 50 W/cm^2 strikes a boundary and is totally reflected. What is the intensity reflection intensity?
50 W/cm^2
Every 10 dB means that the intensity will?
increase ten times
Which of the following components is the dominant contributor to attenuation?
absorption
The intensity transmission coefficient of sound is 99.9%. What percent of sound is reflected back to the transducer?
0.1%
Answer the following question based on the chart above. What does the 3.5 dB/cm represent?
The attenuation coefficient of the sound in the media.
True or False. Acoustic impedance does not equal density x propagation speed.
false
Answer the following question based on the chart above. If the media are soft tissue, what is an estimate of the US frequency?
7 MHz. Approximately 7 MHz, the attenuation coefficient multiplied by 2 approximates the frequency (3.5 x 2 = 7)
The power of a system is at 100% and this is 0 dB. What is the dB change when the system's power is 50%?
-3 dB
dB is mathematical representation with a ____ scale.
logarithmic
Name the three components of attenuation.
absorption, reflection, and scattering
A 3 MHz sound beam travels through two media, it attenuates 5 dB in medium A and 6 dB in medium B. What is the total attenuation that the sound beam undergoes it travels through both media?
11 dB
Answer the following question based on the chart above. What happens at the boundary between media 3 and 4?
reflection may occur
A sound wave with an intensity of 50 W/cm^2 strikes a boundary and is totally reflected. What is the intensity reflection coefficient?
100%
Answer the following question based on the chart Above. What type of incidence is there between media 3 and 4?
oblique*
What is the log of 100?
log of 100 is 2
As the path length increases, the attenuation coefficient of US in soft tissue
remains the same
An ultrasound system operating at 100% power and the power setting is 0 dB. What would the power setting be when the system is operating at 10% power?
-10 dB
What are the units of relative amplitude?
dB
A reduction of intensity to one-half of its original value is?
-3 dB
Which is better to use while examining a carotid artery, a 7.5 or 3.0 MHz transducer?
7.5 MHz
Impedance is important at boundaries ____.
reflections
Total attenuation in soft tissue is related to ____ and ____.
path length and frequency of sound
A hint that is commonly used when solving for logarithms (log). Count the ____.
count the zeros
What is the relationship between US frequency and the attenuation coefficient in soft tissue?
In soft tissue, the attenuation coefficient in dB per centimeter is about 0.5 times the ultrasonic frequency in MHz.
What process occurs as the US passes through all media?
attenuation (scattering, absorption, and reflection)
A signal's power increases from 1 watt to 100 watts. How is this expressed in decibles?
20 dB
What is the log of 1000?
log of 1000 is 3
A sound wave strikes a boundary between two media with different impedances. The angle of incidence is non-orthogonal. Which of the following statements is most correct?
some of the sound may be reflected
Impedance is a characteristic of
only the medium
Attenuation in bone is ____ than soft tissue.
greater than
Note
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