SPI  Flashcards. Read the Question then click “show answer” to see the answer.

SPI - Ultrasound Physics Flashcards

Question 1

Sounds waves are comprised of what?

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Question 1 Explanation: 
Rarefactions and compressions
Question 2

Name the 7 parameters that describe a sound wave.

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Question 2 Explanation: 
1. Period 2. Frequency 3. Amplitude 4. Power 5. Intensity 6. Propagation speed 7. Wavelength
Question 3
Penetration and Axial resolution are related to what sound wave characteristic?
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Question 3 Explanation: 
Frequency
Question 4
What is the formula for intensity?
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Question 4 Explanation: 
I = p / a intensity = power (watts) / beam area (cm2)*Easy (but gross) way to remember this. I pee over an area.
Question 5
What is the propagation speed of sound in soft tissue?
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Question 5 Explanation: 
1540 m/s 1.54 km/s 1.54 mm/us (don't let this one confuse you, it's millimeters per microsecond)
Question 6
If density increases, what happens to the propagation speed?
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Question 6 Explanation: 
It decreases.
Question 7
If density decreases, what happens to the propagation speed?
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Question 7 Explanation: 
It increases.
Question 8
If stiffness decreases, what happens to the propagation speed?
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Question 8 Explanation: 
It decreases.
Question 9
If stiffness increases, what happens to the propagation speed?
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Question 9 Explanation: 
It increases.
Question 10
What is the formula to calculate propagation speed?
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Question 10 Explanation: 
Propagation Speed (mm/microsecond) = Wavelength (mm) X Frequency(MHz)
Question 11
What is the formula to calculate the wavelength?
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Question 11 Explanation: 
Wavelength (mm) = Propagation Speed (mm/microsecond) / Frequency(MHz)
Question 12
What is the formula for frequency?
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Question 12 Explanation: 
Frequency(MHz) = Propagation Speed (mm/microsecond) / Wavelength (mm)
Question 13
Name the five values that are determined by the source:
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Question 13 Explanation: 
Period Frequency Amplitude Power Intensity
Question 14
The propagation speed is determined by what?
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Question 14 Explanation: 
The medium
Question 15
This is determined by both the sound source and the medium.
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Question 15 Explanation: 
The wavelength
Question 16
What can increase the pulse duration of a transducer?
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Question 16 Explanation: 
Lower the frequency (longer period) Increase the cycles in a pulse (more ringing)
Question 17
This measurement of intensity is the most relevant to tissue heating.
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Question 17 Explanation: 
Spatial Peak Temporal Average (SPTA)
Question 18
This form of  intensity has the highest value.
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Question 18 Explanation: 
Spatial Peak Temporal Peak (SPTP)
Question 19
This measurement of intensity has the lowest value.
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Question 19 Explanation: 
Spatial Average Temporal Average (SATA)
Question 20
This measure of intensity is maximum in time.
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Question 20 Explanation: 
Temporal peak (TP)
Question 21
This measurement of intensity is averaged only during the pulse duration (on time only)
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Question 21 Explanation: 
Peak Average (PA)
Question 22
This measurement of intensity is averaged during the pulse repetition period (both on and off times)
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Question 22 Explanation: 
Temporal Average (TA)
Question 23
The rank of intensities from the largest to the smallest is what?
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Question 23 Explanation: 
SPTP > IM > SPPA > SPTA > SATA
Question 24
Pertaining to the original intensity vs the final intensity what does 3 DB mean?
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Question 24 Explanation: 
2 X The final intensity is 2 times greater than the original intensity.
Question 25
Pertaining to the original intensity vs the final intensity what does 6 DB mean?
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Question 25 Explanation: 
2 X 2 X The final is 4 times greater than the original.
Question 26
Pertaining to the original intensity vs the final intensity what does 20 DB mean?
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Question 26 Explanation: 
10 X 10 X The final is 100 times greater than the original.
Question 27
The decrease in intensity, power and amplitude as the sound wave travels is termed what?
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Question 27 Explanation: 
Attenuation
Question 28
Units for attenuation are what?
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Question 28 Explanation: 
dB (must be negative, since the attenuation causes intensity to decrease)
Question 29
In soft tissue if we increase the frequency, what happens to the attenuation?
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Question 29 Explanation: 
It increases. Frequency and Attenuation have a direct relationship. This is why we do not image deep with high frequency sound.
Question 30
Name the three components of attenuation.
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Question 30 Explanation: 
1. Absorption 2. Scattering 3. Reflection
Question 31
What is absorption (form of attenuation)?
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Question 31 Explanation: 
Sound energy converted into heat energy
Question 32
When the boundary between two media have irregularities (with a size similiar to or smaller than pulse's wavelength) then the wave may be redirected into a number of different directions. What does this describe.
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Question 32 Explanation: 
Scattering
Question 33
When the reflector is much smaller than the wavelength, the ultrasounic energy is uniformly diverted in all directions. Higher frequency sound undergoes more of this than lower frequencies. A good example of this is a Red Blood Cell.
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Question 33 Explanation: 
Rayleigh scattering
Question 34
Reflection occurs when what happens?
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Question 34 Explanation: 
When some of the propagating sound energy strikes a boundary between two media and is returned toward the transducer.
Question 35
The amount of attenuation per centimeter (dB/cm) is known as what?
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Question 35 Explanation: 
Attenuation coefficient.
Question 36
In soft tissue, the attenuation coefficient (dB/cm) is estimated at approximately what value?
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Question 36 Explanation: 
Half of the frequency (Mhz), or 0.5 dB/cm/Mhz
Question 37
If impedance is increased then density is what?
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Question 37 Explanation: 
Increased
Question 38
With an increase in propagation speed what change do we see in the density?
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Question 38 Explanation: 
Increased
Question 39
When the path length changes this coefficient does not change.
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Question 39 Explanation: 
Attenuation Coefficient
Question 40
This value is higher in both bone and lung compared to soft tissue.
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Question 40 Explanation: 
Attenuation
Question 41
What two conditions must be met for refraction to occur?
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Question 41 Explanation: 
Differing propogation speeds and an oblique incidence.
Question 42
What change will cause impedance to increase?
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Question 42 Explanation: 
Either an increase in density or an increase in propogation speed. They are proportional. Formula: impedance (rayls) = density (kg/m3) x propagation speed (m/s)
Question 43
What is the formula for impedance?
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Question 43 Explanation: 
Formula: impedance (rayls) = density (kg/m3) x propagation speed (m/s)
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I am the founder and lead Instructor here at ExamRefresh.com. I strive to help those that are entering the field of Ultrasound to be the best that they can be. Ultrasound is my passion.

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