Which statement about intensity ranges is true?

Which statement about intensity ranges is true?

• A. 0.01 to 300 W/cm^2
• B. 1.0 to 100 W/cm^2
• C. 0.1 to 10 W/cm^2
• D. 10 to 1000 W/cm^2

Answer: (D)

Intensities in ultrasound span a wide range depending on the application. Diagnostic imaging uses very low acoustic powers to minimize bioeffects, so the intensities are typically in the milliwatts per square centimeter or a few watts per square centimeter at most. Therapeutic ultrasound, on the other hand, deliberately uses much higher powers to achieve heating or mechanical effects, and its practical intensities range from about 10 up to 1000 W/cm^2 depending on the modality.

That’s why the statement describing a range from 10 to 1000 W/cm^2 is the best fit: it reflects the high-intensity levels used in therapeutic applications, which is much higher than diagnostic imaging. The other ranges either start too low or don’t consistently represent the higher-intensity end characteristic of therapeutic ultrasound.