Which statement about attenuation is true?

Which statement about attenuation is true?

• A. Attenuation is the weakening of the beam due to absorption, scattering, and reflection
• B. Attenuation refers to beam focusing
• C. Attenuation is the increase in frequency
• D. Attenuation only occurs at interfaces

Answer: (A)

Attenuation is the decrease in beam strength as it travels through a medium. In ultrasound, this happens because energy is absorbed by the tissue (turned into heat), scattered out of the main beam, and partially reflected at interfaces where there’s an impedance mismatch. These processes reduce the forward-propagating energy, so the beam appears weaker the farther it travels. The statement that lists absorption, scattering, and reflection captures all the ways energy can leave the forward path, making it the best description. The other ideas—beam focusing, a frequency increase, or attenuation occurring only at interfaces—don’t describe the energy loss along the path in the same way.

Attenuation is the decrease in beam strength as it travels through a medium. In ultrasound, this happens because energy is absorbed by the tissue (turned into heat), scattered out of the main beam, and partially reflected at interfaces where there’s an impedance mismatch. These processes reduce the forward-propagating energy, so the beam appears weaker the farther it travels. The statement that lists absorption, scattering, and reflection captures all the ways energy can leave the forward path, making it the best description. The other ideas—beam focusing, a frequency increase, or attenuation occurring only at interfaces—don’t describe the energy loss along the path in the same way.