Diagnostic Ultrasound: chpt 2
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Created by:
CarrieMines on August 29, 2010
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Description:
Sound, pulsed ultrasound,attenuation, echoes
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17 terms
Terms | Definitions |
|---|---|
 What type of propagation is that in which speed depends on pressure and the wave shape changes? | nonlinear propagation |
| What type of waveform is characterized by a single frequency? | sinusoidal waveform |
| What is the term for the original frequency? | fundamental frequency |
| What is described as the even and odd multiples of the fundamental frequency? | harmonics |
| What is the range of frequencies contained in a pulse? | bandwidth |
| The bandwidth divided by the operating frequency is what? (it is unitless) | fractional bandwidth |
| What is the greatest intensity found across the beam? (usually in the center) | spatial peak |
| What is the average for all values found across the beam? | spatial average |
| What is the greatest intensity found in the pulse as it passes by? | temporal peak |
| What is the average for all values found in a pulse? (the lowest value since it includes the "dead" time between pulses)` | pulse average |
| What is the attenuation that occurs with each cm the sound wave travels? (units are Db/cm) | attenuation coefficient |
| This is a direction of travel of the ultrasound wave perpendicular to the boundary between two media. | perpendicular incidence |
| What determines how much of an incident sound wave is reflected back through the first medium and how much is transmitted into the second medium? (units are rayls) | acoustic impendence |
| If you divide the reflected intensity by the incident intensity you will calculate what? | intensity reflection coefficient |
| If you divide the transmitted intensity by the incident intensity you will calculate what? | intensity transmission coefficient |
| What is the direction of travel of incident ultrasound that is not perpendicular to the boundary between two medias? (the reflected sound does not return to the transducer but travels off in some other direction | oblique incidence |
| What is a change in direction of sound when crossing a boundary? | refraction |
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