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21 Cards in this Set
- Front
- Back
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Infrasound |
<20 Hz |
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Audible sound |
20Hz - 20,000 Hz (20kHz) |
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Ultrasound frequency |
>20 kHz |
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Identify the condition where ultrasound does not exist |
A vacuum |
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Describe the piezoelectric effect |
Converting energy by applying pressure or electrical signals to a crystal |
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Identify the beam angle that ensures strong returning echoes |
Strongest are perpendicular to what you are Imaging. |
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What happens to the sound beam as it travels through the body? |
Attenuation |
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List of forms of attenuation |
🔹 reflections 🔹 scattering 🔹 absorption |
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How the degree of impedance mismatch in tissue density affects the strength of returning echoes |
The higher the degree of impedance mismatch, the greater amount of reflections |
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Acoustic impedance of air |
. 0004 low |
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Acoustic impedance of bone |
7.8 high |
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Which organ conducts sound so low that they cannot be imaged with ultrasound? |
The lungs |
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How does frequency affect resolution |
Increasing the frequency improves resolution but decreases penetration |
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How does frequency affect penetration |
Decreasing the frequency increases penetration but diminishes resolution |
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Explain how transducers should be chosen |
Transducers are chosen according to the structure being examined and the size of the patient |
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Transducer frequency for deep abdomen, OB / GYN, Echo |
2.5 MHz |
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Transducer frequency General abdomen, OB / GYN / Echo |
3.5 MHz |
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Transducer frequency vascular, GYN |
5 MHz |
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Transducer frequency for breast, thyroid, testes |
7.5 MHz |
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Transducer frequencies for breast, thyroid, testes, superficial veins, superficial masses |
10 + MHz |
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Region of the transducer where the beam is relatively narrow |
Focal Zone |
