Which frequency is preferred for heating superficial tissues?

Which frequency is preferred for heating superficial tissues?

• A. 1 MHz
• B. 3 MHz
• C. 5 MHz
• D. 10 MHz

Answer: (B)

Heating with therapeutic ultrasound depends on frequency because higher frequencies are absorbed more quickly and deposit energy in shallower tissues. The 3 MHz setting heats tissues at a moderate shallow depth—typically around 1 to 2 centimeters—making it well suited for targeting superficial muscles, subcutaneous tissue, and other near-surface structures without delivering much energy to deeper areas. The lower frequency would reach deeper tissues, which isn’t ideal when the goal is superficial heating. The very high frequency would confine energy to an even thinner superficial layer, but it can limit effective heating for most superficial targets and is less commonly used in standard therapy. Therefore, 3 MHz provides a practical balance, giving reliable superficial heating for common clinical targets.

Heating with therapeutic ultrasound depends on frequency because higher frequencies are absorbed more quickly and deposit energy in shallower tissues. The 3 MHz setting heats tissues at a moderate shallow depth—typically around 1 to 2 centimeters—making it well suited for targeting superficial muscles, subcutaneous tissue, and other near-surface structures without delivering much energy to deeper areas.

The lower frequency would reach deeper tissues, which isn’t ideal when the goal is superficial heating. The very high frequency would confine energy to an even thinner superficial layer, but it can limit effective heating for most superficial targets and is less commonly used in standard therapy. Therefore, 3 MHz provides a practical balance, giving reliable superficial heating for common clinical targets.