Attenuation in air is described as:

Attenuation in air is described as:

• A. Moderate
• B. Low
• C. Extremely low
• D. Extremely high

Answer: (D)

Attenuation is the loss of wave intensity as it travels through a medium, arising from absorption, scattering, and reflection. For ultrasound, air is a very poor transmitting medium because of its low density and huge impedance mismatch with soft tissues. Most of the ultrasound energy is reflected at the air-tissue boundary, and the energy that does penetrate is quickly dissipated by viscous and thermal losses in the air itself. Because of this, the ultrasound signal decays almost immediately, making any meaningful transmission through air essentially impossible at clinical frequencies. That’s why coupling gels or water baths are used—to replace air and provide a medium where the wave can propagate with far less attenuation. So attenuation in air is described as extremely high.

Attenuation is the loss of wave intensity as it travels through a medium, arising from absorption, scattering, and reflection. For ultrasound, air is a very poor transmitting medium because of its low density and huge impedance mismatch with soft tissues. Most of the ultrasound energy is reflected at the air-tissue boundary, and the energy that does penetrate is quickly dissipated by viscous and thermal losses in the air itself. Because of this, the ultrasound signal decays almost immediately, making any meaningful transmission through air essentially impossible at clinical frequencies. That’s why coupling gels or water baths are used—to replace air and provide a medium where the wave can propagate with far less attenuation. So attenuation in air is described as extremely high.