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)

Ultrasound intensity varies a lot because the energy you deliver depends on the application. Imaging uses very low energy to avoid heating, while therapeutic uses much higher energy to produce tissue effects, sometimes reaching into the tens, hundreds, or even thousands of W/cm^2 in high‐energy focused applications. So a range of about 10 to 1000 W/cm^2 captures the broad spectrum of therapeutic levels and includes the upper end used in focused therapies, which is why this statement is true. The other ranges either miss the high end seen in therapies or start too low to represent typical therapeutic exposures.