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27 Cards in this Set
- Front
- Back
What is the speed of sound in soft tissue? |
1540 m/s |
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Sound waves can be described best as... |
Mechanical and longitudinal |
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1 MHz is how many cycles per second? |
1 million cycles per second |
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10,000 m is how many km |
10 km |
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The effects of the sound wave upon the biologic tissue through which it passes is called? |
Biologic effects |
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What are the acoustic variables? |
Pressure, density, and distance |
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As frequency increases, propagation speed decreases. |
False |
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Frequency of audible sound |
20 Hz and 20,000Hz |
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True or False: Lower numerical values of axial resolution indicates a shorter pulse, creating a more accurate image. |
True |
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Wavelength is determined by... |
Sound source and medium |
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Propagation speed is determined by... |
Medium |
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How are Pulse repetition periods (PRP) and Pulse repetition frequency (PRF) related? |
Inversely related to each other |
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What are the 7 acoustic parameters |
Frequency, period, wavelength, speed, intensity, amplitude,and power |
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What is the concentration of the energy in a sound beam? |
Intensity |
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Sound moving in decreased pressure and density is called |
Rarefactions |
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For each cm of reflector depth in soft tissue how many microseconds is the time of flight? |
13 microseconds |
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The time of flight is ____ related to the depth |
Directly |
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The most relevant intensity with respect to tissue heating... |
SPTA |
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T or F: 26 microseconds= 4 cm total distance traveled |
True |
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Whatever percentage remains must be the intensity transmission coefficient. There must be what kind of energy at the boundary? |
Conservation of energy |
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T or F: US penetrates further with lower frequency |
True |
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Sound waves weakens as they propagate in a medium. This decrease in intensity, power, and amplitude as sound travels is called... |
Attenuation |
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What are the units that all intensities have? |
W/cm² |
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What are the two bio effects? |
Heat and cavitation |
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A reduction in the intensity of a sound beam to one quarter of its original value is how many dB? |
-6 dB |
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Advantage of describing sound weakening with an attenuation coefficient is that it's value ____ _____, regardless how far it travels |
Remains constant |
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is the change in directions of a wave propagation when traveling from one medium to another. |
Refraction |