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physics final
| Question | Answer |
|---|---|
| what may happen to a color flow image if the gain is set too low ? | false indication of low flow |
| what is the benefit of steering the color field of view (color box) during color flow imaging? | creating a better doppler angle to the red blood cells |
| Adjusting the velocity scale on the color doppling imaging system changes what parameter? | PRF |
| what do lighter shades of color depict in color doppler? | faster velocities (lighter=brighter shades) |
| what will happen if the scanning systems settings are not carefully documented and reused during QA test | false indication of dedgradation |
| according to dr. lili, what component of the modern scanning system is most likely to fail | the trandsucer |
| which component creates the doppler shift during cardiovascular applications | red blood cells |
| in medical imaging, what is the range of most doppler shift frequencies | 2MHz- 20 MHz ? |
| what describes a doppler signal processing technique that removes backscatter signals created by stationary signals | wall filter |
| the doppler shift can only be observed when | when the sound source is relative to a stationary |
| TRUE OR FALSE: when the doppler angle increases the doppler shift also increases | false |
| how many times per cycle must the doppler system sample the frequencies to prevent aliasing | two |
| whats the mathematical process used to break doppler shift frequencies into individual frequencies | FFT (associated with spectral) |
| how is a spectral system able to specify a specific depth for gathering blood flow information | the gate (gives us range specification) |
| what is the function of the wall filter in a doppler system | remove clutter |
| what technique can not eliminate alisasing: - increasing frequency -increasing scale -increasing PRF -lowering angle of insonification | i think its increasing frequency (this is the one she kept going back and forth on) |
| What is the major advantage of continuous wave doppler to pulse wave doppler | will not aliase |
| how does a color doppler system show blood flow that is accelerating | brighter shades of color |
| when is range ambiguity most likely to occur with a pulsed wave doppler system | in shallow depths |
| in a positive doppler shift, the transmitted frequency should be | smaller than the detected frequency |
| if the doppler shift frequency increases the relative velocity should... | increase |
| what are three situations where the echogenecity of blood would increase | stationary blood, turbulent flow, thrombus |
| how does a specular relflection at the wall of a vessel reduce the intensity of a sound beam used to interrogate it | it reflects most of the energy back to the transducer |
| what does turbulant blood flow usually indicate | cardiovascular disease |
| whats considered normal hematocrit for a healthy female | 42% |
| what effect with polycythemia vera have on a patient's hematocrit | increase it |
| the ability to do work | energy |
| the measure of the abilty to hold change in volume over time | capacitance |
| the measure of force per unit area | pressure |
| how does an increase in resistance to flow in an aortic valce affect the heart in the long run | the left ventricle is going to be affected |
| which term describes the increase in pressure in a flowing fluid distal to a narrowing of a tube | pressure recovery |
| what type of flow is arterial side of the body | laminar |
| flow profile demonstrating slow flow at walls with increasing velocities in the center of the vessel | parbolic |
| when examining Posuiallie's law, what effect will doubling a vessels radius have on the volume flow rate | increases by a factor of 16 |
| where is the highest resistance to blood flow found in the cardiovascular system | arterioles |
| what % of blood is stored in the venous system at rest | 65-70% |
| what is pulsatile blood flow | rapid acceleration, gradual deacceleration in diastole |
| flow that changes with respiration | phasic flow (venous flow) |
| how does the body maintain volumetric flow to distal organs in the presence of an arterial stenosis | dilation of the arterial beds, velocity increases, collateral pathways form |
| what makes cardiac ouput increase? | exercise |
| which statement about hemodynamics is correct for vessels connected in a series | overall resistance increases |
| what happens in the vascular system when an arterial stenosis lowers the amount of blood going to an organ? | vasodilation ? |
| when examining P. Law, what does reducing the length of a vessel by half do to volumetric flow? | doubles it |
Created by:
alliemika