How does increasing frequency affect attenuation and penetration in soft tissue?

How does increasing frequency affect attenuation and penetration in soft tissue?

• A. Penetration increases with higher frequency
• B. Attenuation is independent of frequency
• C. Attenuation increases, reducing penetration
• D. Attenuation decreases with higher frequency

Answer: (C)

In soft tissue, how far the ultrasound wave travels before it becomes too weak is controlled by attenuation, which increases as frequency rises. This happens because more energy is lost to absorption and scattering at higher frequencies. So higher frequency waves are damped more quickly, reducing how deeply they can penetrate. This is why you get better detail (higher resolution) with higher frequencies but shallower imaging depth, and why the attenuation coefficient in soft tissue is often cited as roughly proportional to frequency (for example around 0.5 dB/cm per MHz). Consequently, increasing frequency leads to more attenuation per centimeter and therefore less penetration.

In soft tissue, how far the ultrasound wave travels before it becomes too weak is controlled by attenuation, which increases as frequency rises. This happens because more energy is lost to absorption and scattering at higher frequencies. So higher frequency waves are damped more quickly, reducing how deeply they can penetrate. This is why you get better detail (higher resolution) with higher frequencies but shallower imaging depth, and why the attenuation coefficient in soft tissue is often cited as roughly proportional to frequency (for example around 0.5 dB/cm per MHz). Consequently, increasing frequency leads to more attenuation per centimeter and therefore less penetration.