In continuous ultrasound, what is the duty cycle and effect?

In continuous ultrasound, what is the duty cycle and effect?

• A. 100% duty cycle, sound waves are present, thermal
• B. 50% duty cycle, nonthermal
• C. 0% duty cycle, no effect
• D. 25% duty cycle, cavitation only

Answer: (A)

Continuous ultrasound delivers energy without interruption, so the duty cycle is 100%. With energy flowing constantly, tissue absorbs it and heat builds up, producing a thermal effect. This heating is the primary outcome of continuous US, which is why it’s typically used when warming tissue or increasing tissue extensibility is the goal. Lower duty cycles deliver energy in pulses, reducing heating and emphasizing nonthermal mechanical effects; 0% would mean no energy delivery at all, and the idea of cavitation-only doesn’t describe continuous ultrasound, where heating dominates.

Continuous ultrasound delivers energy without interruption, so the duty cycle is 100%. With energy flowing constantly, tissue absorbs it and heat builds up, producing a thermal effect. This heating is the primary outcome of continuous US, which is why it’s typically used when warming tissue or increasing tissue extensibility is the goal. Lower duty cycles deliver energy in pulses, reducing heating and emphasizing nonthermal mechanical effects; 0% would mean no energy delivery at all, and the idea of cavitation-only doesn’t describe continuous ultrasound, where heating dominates.