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Attenuation, Reflection, and Refraction Flashcards

7 cards from real ARDMS SPI practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. Which tissue type has the highest attenuation coefficient at a given frequency?

    Answer: Bone

    Bone has the highest attenuation coefficient among soft tissues and calcified structures due to its density and composition.

  2. When a sound beam travels from muscle into fat, which phenomenon occurs because fat has a lower propagation speed?

    Answer: Refraction

    Refraction occurs when sound crosses an interface at an oblique angle between media with different propagation speeds, causing the beam to bend.

  3. What is the half-value layer (HVL) in ultrasound attenuation?

    Answer: The depth at which intensity is reduced by 50%

    The half-value layer is the tissue depth at which the beam's intensity is reduced to half its original value.

  4. A specular reflector produces a strong echo only when:

    Answer: The beam strikes the surface perpendicularly

    Specular reflectors return maximum echo amplitude when the beam strikes perpendicular (90°) to the smooth, large surface.

  5. How does increasing ultrasound frequency affect attenuation in soft tissue?

    Answer: Attenuation increases

    Attenuation increases with frequency because higher-frequency sound waves are more readily absorbed and scattered by tissue.

  6. Which formula correctly relates the attenuation in dB for soft tissue?

    Answer: Attenuation (dB) ≈ 0.5 × frequency (MHz) × depth (cm)

    The standard approximation is 0.5 dB/cm/MHz for soft tissue, so total attenuation = 0.5 × frequency × depth.

  7. Rayleigh scattering is characterized by scatterers that are:

    Answer: Much smaller than the wavelength

    Rayleigh scattering occurs when scatterers (e.g., red blood cells) are much smaller than the ultrasound wavelength, scattering energy in all directions.