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29 Cards in this Set
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- Back
- 3rd side (hint)
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What is attenuation? |
Is how sound weakens as it travels through the body |
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Is a measurement used to report (attenuation) changes; used to report the relative changes of sound beams. A ratio |
Decibel notation |
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What is the unit for attenuation? |
dB (decibel) |
dog Butt |
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This represents the number of 10s that are multiplied to create a number |
Log |
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Is the number of decibels of attenuation that occurs when sound travels one centimeter |
Attenuation coefficient |
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Is a Mathew mathematical construct or method of rating numbers |
Logarithm |
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Describes Ultrasound signals increasing in strength |
Positive decibels |
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Describes Ultrasound signals decreasing in strength |
Negative decibels |
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Is when sound strikes a boundary and a portion of the wave's energy may be redirected back to the sound source |
Reflection |
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Occurs when sound waves reflect off an irregular boundary and radiate in different directions |
Diffuse reflection |
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Occurs when the ultrasound beam hits a smooth boundary, and the sound is reflected in only one direction |
Specular reflection |
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Is when ultrasound energy is converted to another energy form and is the most sizable component of attenuation |
Absorption |
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Is the distance sound travels in a tissue that reduces intensity by 1/2 |
Half-value layer thickness aka half-boundary layer |
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Random redirection of sound waves in many directions |
Scattering |
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When the sound beam is redirected equally in all directions |
Rayleigh scattering |
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Is the process of sound energy being extracted from a wave by absorption, scattering and reflection |
Attenuation |
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An angle that is greater than 90° |
Obtuse angle |
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An angle less than 90° |
Acute angle |
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An angle exactly 90° |
Right angle |
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Is the acoustic resistance to sound traveling in a medium |
Impedance |
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Reflected intensity+ transmitted intensity= |
Incident intensity |
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Is the intensity of a sound beam that returns after striking a boundary |
Reflected intensity |
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Is the sound waves intensity before it strikes a boundary |
Incident intensity |
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Is when the incident angle of sound beam strikes a boundary at an angle other than 90° |
Oblique incidence |
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Is the intensity of a sound beam that continues forward after striking a boundary |
Transmitted intensity |
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Intensity reflection coefficient (IRC)Is a percentage of ultrasound intensity that bounces back when the beam strikes interface between two media |
Intensity reflection coefficient (IRC) |
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Percentage of ultrasound intensity that continues when the beam strikes interface between two media |
Intensity transmission coefficient |
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Intensity reflection coefficient + intensity transmission coefficient = |
100% |
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Is the amount of ultrasound intensity reflected at a boundary in soft tissue (%) |
<1% |
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