What is the primary characteristic of pulsed ultrasound?

The primary characteristic of pulsed ultrasound is the periodic interruptions of waves. In pulsed ultrasound therapy, the ultrasound energy is emitted in a series of bursts rather than a continuous stream. This pulsing action creates a pattern where the ultrasound waves are alternately transmitted and then stopped, allowing for specific therapeutic effects.

This pulsing nature of ultrasound is particularly beneficial for certain therapeutic applications, such as promoting tissue healing and reducing pain. The intervals of no output allow for periods of rest for the tissues, which can minimize thermal effects and help to target the treatment more effectively. By adjusting the duty cycle, practitioners can control the amount of energy delivered to the tissues, enhancing the treatment's efficacy while reducing the risk of overheating.

The other choices do not accurately describe pulsed ultrasound, as they focus on aspects not characteristic of pulsed waveforms. Uninterrupted streams refer to continuous wave ultrasound, while the injection of medication relates to other modalities, such as phonophoresis. Lastly, constant high frequency output also describes a continuous wave rather than a pulsed approach.