Sound wave properties, transducer types, resolution, Doppler physics, artifacts and knobology for the ARDMS SPI exam.
38 cards · basic cards · AI-written, checked twice. Edit anything.
- What unit is used to measure the frequency of a sound wave?
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Hertz (Hz), cycles per second- How are frequency and period related?
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Frequency equals 1 divided by period (f = 1/T)- What frequency range is typically used in diagnostic medical ultrasound?
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About 2 to 15 MHz- What property of a medium primarily determines the speed of sound through it?
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The medium's stiffness and density (not the sound's frequency)- What is the average propagation speed of sound used for soft tissue in ultrasound machines?
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1,540 meters per second- Is the propagation speed of sound in bone faster or slower than in soft tissue?
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Faster, because bone is stiffer- What is acoustic impedance?
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The density of a medium multiplied by the propagation speed of sound in it- What causes an ultrasound beam to be reflected at a tissue boundary?
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A difference in acoustic impedance between the two adjacent media- What is attenuation in ultrasound?
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The progressive loss of sound wave intensity as it travels through tissue- What are the three main mechanisms of attenuation?
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Absorption, scattering, and reflection- What is the approximate attenuation coefficient of soft tissue?
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About 0.5 dB per centimeter per MHz- What is the piezoelectric effect?
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The production of an electrical voltage when a crystal is mechanically deformed, and the reverse (deformation when voltage is applied)- What material is commonly used as the active element inside an ultrasound transducer?
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Lead zirconate titanate (PZT)- What is the Curie point of a piezoelectric crystal?
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The temperature above which the crystal permanently loses its piezoelectric properties- What is the purpose of the damping (backing) material in a transducer?
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To shorten the pulse length, improving axial resolution, by absorbing backward-traveling vibrations
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