What duty cycle is used in pulsed ultrasound to achieve nonthermal effects?

What duty cycle is used in pulsed ultrasound to achieve nonthermal effects?

• A. 40%
• B. 20% or lower
• C. 60%
• D. 80%

Answer: (B)

The main idea is that duty cycle controls how long the ultrasound is on versus off in each cycle, which directly influences heating. Nonthermal effects rely on mechanical interactions—like cavitation and microstreaming—rather than temperature rise. To favor those mechanical effects while minimizing heating, you keep the on-time fraction low. A duty cycle around 20% or lower provides enough peak energy to promote mechanical stimulation but lets most of the energy be off between bursts, so the tissue doesn’t heat up significantly. Higher duty cycles increase the average energy delivered and tend to produce more thermal effects, which shifts the effect away from nonthermal mechanisms.

The main idea is that duty cycle controls how long the ultrasound is on versus off in each cycle, which directly influences heating. Nonthermal effects rely on mechanical interactions—like cavitation and microstreaming—rather than temperature rise. To favor those mechanical effects while minimizing heating, you keep the on-time fraction low. A duty cycle around 20% or lower provides enough peak energy to promote mechanical stimulation but lets most of the energy be off between bursts, so the tissue doesn’t heat up significantly. Higher duty cycles increase the average energy delivered and tend to produce more thermal effects, which shifts the effect away from nonthermal mechanisms.