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PhysicsModule5
Questions from Module 5 of the Physics component
| Question | Answer |
|---|---|
| Describe the Doppler Effect. | Waves transmitted from a moving object have a freq dependent upon relative velocity between transmitter and observer. |
| Explain the Doppler shift phenomenon under the following conditions:Stationary source and stationary receiver. | Frequency is unchanged, because neither of the objects are moving. |
| Explain the Doppler shift phenomenon under the following conditions:Stationary source and moving receiver. | If receiver is moving TOWARDS the Tx- frequency increasesIf receiver is moving AWAY from the Tx- frequency decreases |
| Discusss the relationship between Doppler (frequency)shift, Doppler source/target speed, and Doppler source/target direction. | Doppler shift is the absolute difference between the frequency of the source and the target's echoes. Higher velocities produce higher frequency shifts. |
| What kind of information is presented in a CW Doppler display? | There is no range resolution,it samples all flow along the path, there is fill-in of the window, and displays high velocity without aliasing |
| What kind of information is presented in a PW Doppler display? | It's range specific, subject to aliasing, affected by sample box size, and Max velocity indirectly prop to US freq |
| Describe triphasic flow. | Bidirectional flow (dips below the baseline) that feeds high resistance beds, examples: Ao, femoral arteries, ECA |
| Describe biphasic flow. | Unidirectional flow that feeds low resistance beds, examples: ICA, RA |
| Describe monophasic flow | Unidirectional flow that feeds very low resistance beds, examples, L/R hepatic, arcuate artery |
| Describe laminar flow | indicated by an “open” window on spectral analysis **center of vessel has highest flow freq. / Majority of vessels in body have laminar flow |
| Describe turbulent flow. | blood no longer flows in one direction along the vessel's length but occurs crosswise; indicated by a filled-in window on spectral analysis |
| Describe plug flow. | blood is going at same velocity in the vessel; large diameter aa (Ao and common iliac)/triphasic (bidirectional) |
| Describe parabolic flow. | same as laminar flow |
| Give examples of quantitative data. | Numeric data: peak/mean velocity, pulsatility/resistive index, area under curve, slope |
| Give examples of qualitative data. | descriptive data: characteristics of wave form, presence or absence of flow, patancy of flow, direction of flow, laminar vs turbulent, phasic vs continuous, spectral broadening |
Created by:
sbeard1
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