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16 Cards in this Set
- Front
- Back
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Explain positive Doppler shifts. |
Towards the transducer, returning frequency is higher than transmitting frequency. E x a train moving towards you |
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Explain a negative Doppler shift |
Away from the transducer, returning frequency is lower than transmitting frequency. Ex: an airplane flying away from you. |
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Identify the required number of pzt crystals needed for continuous wave |
At least 2 PCT crystals for CW. One talks one listens |
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Identify the required number of pzt crystals needed for pulse Doppler PW |
Only one crystal is needed. Transmits impulse, then waits for returning Echo. |
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Which type of Doppler range is ambiguous? |
CW. Sometimes called a blind Doppler. (no range gate, depth not known - range ambiguity) |
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According to the color bar, which portion depicts flow towards the transducer and which depicts Flow Away from the transducer? |
🔹Top color = always towards trans. 🔹Bttm color = always away |
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Describe the artirial flow pattern |
Sounds like your heartbeat. Oxygenated blood coming from the left ventricle of the heart into the circulation. |
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Describe the venous flow pattern |
Continuous rhythmic flow. Affected by respiration. Deoxygenated blood returning to the heart |
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Describe the high resistance arterial flow pattern |
High systolic Peak and low diastolic flow. Describe as pulsatile. Between incident pulses, hydraulic Reflections travel back up the vessel from the periphery, producing flow reversal. |
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Describe low resistance arterial flow pattern. |
Relatively high level of flow in diastole. Described as continuous. Steady flow throughout systole and diastole. |
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Identify High Resistance vascular beds |
High Resistance vascular beds, 🔹external carotid (ECA) , 🔹subclavian, 🔹aorta, 🔹iliac, 🔹extremity arteries. |
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Identify low resistance vascular beds |
Organs Constantly need flow. 🔹Internal carotid (ICA) 🔹vertebal 🔹Cranial arteries 🔹Renal arteries 🔹Splenic 🔹Celiac 🔹Hepatic arteries |
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Describe Normal and abnormal flow |
🔹Laminar flow = normal 🔹Turbulent flow = maybe abnormal Indicating stenosis. |
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Describe spectral broadening |
Fill in of spectral window. May indicate stenosis |
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Explain how aliasing and can be fixed |
🔹Increase PRF - ⬆️ sampling rate 🔹 Move baseline |
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Explain what ALARA stands for. |
🔹As Low As Reasonably Achievable 🔹Scanning safely |
