Which statement correctly describes pulsed ultrasound compared to continuous ultrasound?

Which statement correctly describes pulsed ultrasound compared to continuous ultrasound?

• A. Pulsed minimizes thermal and emphasizes mechanical effects
• B. Pulsed increases thermal effects more than continuous
• C. Pulsed delivers energy at 100% duty cycle
• D. Pulsed has no clinical use

Answer: (A)

Pulsed ultrasound delivers energy in bursts with off time, giving a low duty cycle. This lowers the average intensity and curtails heating, so thermal effects are minimized. The on–off pattern also promotes mechanical effects from the ultrasound waves—like microstreaming and cavitation—without overheating tissue. Continuous ultrasound, by contrast, keeps energy on, which raises tissue temperature and emphasizes thermal effects. So the statement that pulsed minimizes thermal effects and emphasizes mechanical effects is the best description.

Pulsed ultrasound delivers energy in bursts with off time, giving a low duty cycle. This lowers the average intensity and curtails heating, so thermal effects are minimized. The on–off pattern also promotes mechanical effects from the ultrasound waves—like microstreaming and cavitation—without overheating tissue. Continuous ultrasound, by contrast, keeps energy on, which raises tissue temperature and emphasizes thermal effects. So the statement that pulsed minimizes thermal effects and emphasizes mechanical effects is the best description.