Increasing the duty cycle during therapeutic ultrasound will most directly increase which of the following?

Increasing the duty cycle during therapeutic ultrasound will most directly increase which of the following?

• A. Tissue heating
• B. Cavitation risk
• C. Mechanical disruption
• D. Cooling

Answer: (A)

Duty cycle is the fraction of time the ultrasound is actively emitting during each pulse. When you raise the duty cycle, more energy is delivered to the tissue over a given period, so the tissue absorbs more energy and the temperature rises more—directly increasing heating. While higher duty cycle can influence other effects, the most immediate and direct outcome is increased heating because the tissue is receiving energy more continuously and has less time to dissipate it between bursts. Cavitation risk and mechanical disruption depend more on peak pressures and other parameters, and cooling actually becomes harder, not easier, as the ultrasound stays on longer. So the correct outcome is tissue heating.

Duty cycle is the fraction of time the ultrasound is actively emitting during each pulse. When you raise the duty cycle, more energy is delivered to the tissue over a given period, so the tissue absorbs more energy and the temperature rises more—directly increasing heating. While higher duty cycle can influence other effects, the most immediate and direct outcome is increased heating because the tissue is receiving energy more continuously and has less time to dissipate it between bursts. Cavitation risk and mechanical disruption depend more on peak pressures and other parameters, and cooling actually becomes harder, not easier, as the ultrasound stays on longer. So the correct outcome is tissue heating.