3 MHz - absorption occurs up to

3 MHz - absorption occurs up to

• A. 6 cm
• B. 12 cm
• C. 1 cm
• D. 2.5 cm

Answer: (D)

When using therapeutic ultrasound, the depth to which energy is absorbed depends on the frequency: higher frequencies deposit energy more quickly and therefore penetrate less deeply. At 3 MHz, the energy is mainly absorbed in superficial tissues, typically within about 2 to 3 cm, with 2.5 cm being a commonly cited depth. This makes 2.5 cm the best fit for the depth of absorption at 3 MHz. The other depths (much deeper like 6 cm or 12 cm, or very shallow like 1 cm) don’t align with how 3 MHz behaves in soft tissue.

When using therapeutic ultrasound, the depth to which energy is absorbed depends on the frequency: higher frequencies deposit energy more quickly and therefore penetrate less deeply. At 3 MHz, the energy is mainly absorbed in superficial tissues, typically within about 2 to 3 cm, with 2.5 cm being a commonly cited depth. This makes 2.5 cm the best fit for the depth of absorption at 3 MHz. The other depths (much deeper like 6 cm or 12 cm, or very shallow like 1 cm) don’t align with how 3 MHz behaves in soft tissue.