What is the typical ultrasound frequency range used therapeutically?

• A. 0.75-3.0 MHz
• B. 1.0-5.0 MHz
• C. 5.0-10.0 MHz
• D. 10-20 MHz

Answer: (A)

Therapeutic ultrasound delivers energy at frequencies chosen to control how deep the energy penetrates into tissue. Lower frequencies travel deeper, while higher frequencies are absorbed more quickly and affect only superficial layers. The standard therapeutic window is about 0.75 to 3.0 MHz, which provides a balance to reach tissues such as muscle and tendons without causing excessive heating of the skin. Frequencies well above this range don’t penetrate far and aren’t typical for treating deeper structures, while ranges that only consider very high frequencies are generally not used for standard therapeutic heating. For these reasons, 0.75 to 3.0 MHz is the typical, appropriate range.