Attenuation coefficient is typically expressed as

Attenuation coefficient is typically expressed as

• A. 3 dB/MHz
• B. 0.6 dB/cm/MHz
• C. 2 dB/cm
• D. 1 dB/cm/Hz

Answer: (B)

Attenuation coefficient describes how quickly the ultrasound signal loses intensity as it travels, and it is expressed as dB per centimeter per megahertz. This format captures both the distance traveled and the frequency dependence, since higher frequencies attenuate more and longer paths accumulate more loss. In soft tissues, a typical value is about 0.5–0.7 dB/cm/MHz, with 0.6 dB/cm/MHz used as a standard approximation. So the total attenuation over a depth L at a frequency f MHz is roughly 0.6 × f × L dB. The other expressions don’t fit because they either omit the distance term, omit the frequency dependence, or use an incorrect unit (per Hz instead of per MHz).

Attenuation coefficient describes how quickly the ultrasound signal loses intensity as it travels, and it is expressed as dB per centimeter per megahertz. This format captures both the distance traveled and the frequency dependence, since higher frequencies attenuate more and longer paths accumulate more loss. In soft tissues, a typical value is about 0.5–0.7 dB/cm/MHz, with 0.6 dB/cm/MHz used as a standard approximation. So the total attenuation over a depth L at a frequency f MHz is roughly 0.6 × f × L dB. The other expressions don’t fit because they either omit the distance term, omit the frequency dependence, or use an incorrect unit (per Hz instead of per MHz).