What acoustic parameter determined by the product of tissue density and sound velocity (Z = rho * v) (Hard) governs echo reflection in ultrasound?
Answer and explanation
Correct answer: C. Acoustic impedance
- Step 1: When an ultrasound beam hits a boundary between two anatomical tissues, the reflected echo fraction depends on the difference in acoustic impedance (Z = rho v). Step 2. Large differences in acoustic impedance (e.g. between soft tissue and bone, or tissue and air) cause strong reflections. Answer: Acoustic impedance. Why not the others:* Capacitance measures electrical charge storage; attenuation measures intensity loss; permittivity measures dielectric response.
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