At a tissue interface, what primary ultrasound phenomenon occurs due to impedance mismatch?

At a tissue interface, what primary ultrasound phenomenon occurs due to impedance mismatch?

• A. Reflection
• B. Refraction
• C. Absorption
• D. Diffraction

Answer: (A)

At a boundary between two tissues with different acoustic impedances, part of the incoming ultrasound energy is reflected back toward the transducer. This boundary reflection is what generates the echoes that create the ultrasound image, and its strength increases with greater impedance difference. This is why tissue interfaces produce the bright echoes seen on the screen. Refraction would bend the transmitted beam, absorption would mainly reduce energy along the path, and diffraction involves bending around edges rather than the boundary reflections that form the image.

At a boundary between two tissues with different acoustic impedances, part of the incoming ultrasound energy is reflected back toward the transducer. This boundary reflection is what generates the echoes that create the ultrasound image, and its strength increases with greater impedance difference. This is why tissue interfaces produce the bright echoes seen on the screen. Refraction would bend the transmitted beam, absorption would mainly reduce energy along the path, and diffraction involves bending around edges rather than the boundary reflections that form the image.