To maintain the same tissue heating when switching to water immersion ultrasound applied to the distal calf, which adjustment to parameters would be best?

• A. Utilize the same treatment parameters
• B. Increase the intensity and decrease the time
• C. Increase the intensity and increase the time
• D. Change the frequency to 3 MHz and increase the time

Answer: (C)

When you want the same amount of tissue heating, the key is delivering the same energy to the target tissue. Water immersion changes how ultrasound energy is coupled and how heat is dissipated, so the tissue at depth (like in the distal calf) tends to receive less energy at the same parameters. To compensate, you increase the energy delivered by boosting both intensity and duration. That raises the total energy reaching the tissue to match the prior heating level.

Changing the frequency to 3 MHz would concentrate heating more superficially and is less effective for deeper targets, even with longer time, so it wouldn’t reliably achieve the same heating in the distal calf.