In ultrasound, increasing frequency results in what change to attenuation?

• A. Decreased attenuation
• B. No change in attenuation
• C. Increased attenuation
• D. Attenuation only at tissue interfaces

Answer: (C)

Attenuation is the loss of sound energy as it travels through tissue, and the rate of that loss (the attenuation coefficient) increases with frequency. In soft tissue this relationship is roughly proportional, so higher frequency waves lose more energy per centimeter than lower frequency waves. That means increasing frequency boosts attenuation, making the beam weaken more quickly as it moves deeper. This is why higher-frequency ultrasound gives better resolution but less penetration. The other options don’t fit because attenuation isn’t reduced with frequency, isn’t constant, and isn’t confined only to tissue interfaces—the energy loss accumulates along the path through the tissue.