What does attenuation refer to in ultrasound physics?

• A. Increasing intensity of sound as it passes through medium
• B. Decreasing intensity of sound as it passes through medium
• C. Increasing frequency of the sound
• D. Change in color of the image

Answer: (B)

Attenuation is the reduction of the ultrasound beam’s intensity as it travels through tissue. This loss comes from absorption (energy turned into heat), scattering (sound redirected in many directions), and reflections at interfaces. Because attenuation increases with frequency, higher-frequency beams lose more energy and don’t penetrate as deeply, making deeper structures appear dimmer on the image. So attenuation is about decreasing intensity, not increasing it, not increasing frequency, and not a color change in the image.