Identify the option that is not an optimal dose parameter for heating deep muscle.

Identify the option that is not an optimal dose parameter for heating deep muscle.

• A. 3 MHz, 1.5 W/cm2, 14 min
• B. 1 MHz, 1.5 W/cm2, 14 min
• C. 1 MHz, 0.5 W/cm2, 8 min
• D. 3 MHz, 0.5 W/cm2, 8 min

Answer: (A)

The key factor for heating depth with therapeutic ultrasound is the frequency. Lower frequency (about 1 MHz) penetrates deeper into tissue, while higher frequency (about 3 MHz) is absorbed more superficially and mainly heats tissues near the surface. So a setting that uses 3 MHz will deposit most of its energy in the superficial layers and is unlikely to raise deep muscle temperature effectively, even if the intensity and duration are reasonably high. That’s why the combination with 3 MHz is not suitable for heating deep muscle. A deeper-heating setup would typically use 1 MHz with an appropriate intensity (around 1.0–1.5 W/cm²) for a duration that achieves the target therapeutic effect.

The key factor for heating depth with therapeutic ultrasound is the frequency. Lower frequency (about 1 MHz) penetrates deeper into tissue, while higher frequency (about 3 MHz) is absorbed more superficially and mainly heats tissues near the surface. So a setting that uses 3 MHz will deposit most of its energy in the superficial layers and is unlikely to raise deep muscle temperature effectively, even if the intensity and duration are reasonably high. That’s why the combination with 3 MHz is not suitable for heating deep muscle. A deeper-heating setup would typically use 1 MHz with an appropriate intensity (around 1.0–1.5 W/cm²) for a duration that achieves the target therapeutic effect.