What is the therapeutic US frequency range?

• A. 0.1 - 0.5 MHz
• B. 0.75 - 3 MHz
• C. 2 - 6 MHz
• D. 5 - 10 MHz

Answer: (B)

Therapeutic ultrasound relies on frequency to control how far into tissue the sound waves travel and how much heat they generate. The standard therapeutic window is 0.75 to 3 MHz. Lower frequencies within this range reach deeper tissues, while higher frequencies deposit energy more in superficial layers. This range lets clinicians tailor treatment to the target depth by choosing the appropriate frequency and intensity. Frequencies outside this range are not typical for standard therapeutic US: too low and penetration shifts toward non-therapeutic uses, too high and energy is confined to very shallow tissue. So, the frequency range used in therapy is 0.75–3 MHz.