What is the duty cycle in ultrasound therapy?

What is the duty cycle in ultrasound therapy?

• A. Duty cycle
• B. Frequency
• C. Amplitude
• D. Wavelength

Answer: (A)

Duty cycle is the fraction of time that ultrasound energy is actually being emitted during each treatment cycle. It’s calculated as the on-time divided by the total cycle time (on time plus off time). For example, if the transducer is on for 2 milliseconds and off for 8 milliseconds, the duty cycle is 2 / (2 + 8) = 0.2, or 20%. This pattern matters because it determines how much heating occurs. A higher duty cycle delivers more energy over the same period and increases tissue heating, while a lower duty cycle reduces heating and emphasizes non-thermal, mechanical effects like microstreaming and cavitation. Continuous ultrasound is a 100% duty cycle, with energy on all the time. Other ultrasound parameters are different: frequency is how often the wave cycles per second, amplitude is the strength of the energy, and wavelength is the distance between successive wave crests.

Duty cycle is the fraction of time that ultrasound energy is actually being emitted during each treatment cycle. It’s calculated as the on-time divided by the total cycle time (on time plus off time). For example, if the transducer is on for 2 milliseconds and off for 8 milliseconds, the duty cycle is 2 / (2 + 8) = 0.2, or 20%.

This pattern matters because it determines how much heating occurs. A higher duty cycle delivers more energy over the same period and increases tissue heating, while a lower duty cycle reduces heating and emphasizes non-thermal, mechanical effects like microstreaming and cavitation. Continuous ultrasound is a 100% duty cycle, with energy on all the time.

Other ultrasound parameters are different: frequency is how often the wave cycles per second, amplitude is the strength of the energy, and wavelength is the distance between successive wave crests.