Which statement best describes the energy delivery difference between pulsed and continuous ultrasound?

Which statement best describes the energy delivery difference between pulsed and continuous ultrasound?

• A. Pulsed delivers energy in bursts with off times, while continuous delivers energy continuously.
• B. Pulsed uses higher frequency than continuous.
• C. Pulsed always travels faster in tissue.
• D. Pulsed beams are always larger in area.

Answer: (A)

Energy delivery pattern distinguishes pulsed from continuous. Pulsed ultrasound sends energy in short bursts with off times between them. Those silent intervals mean the energy is not delivered all the time, so the average energy reaching the tissue can be kept lower by adjusting the duty cycle. Continuous ultrasound, on the other hand, emits energy without interruption, delivering energy steadily and thus producing a higher average dose and greater thermal effect at the same peak intensity. The frequency, speed of sound in tissue, and beam size are not defined by whether the emission is pulsed or continuous; frequency is set by the transducer, speed of sound is a tissue property, and beam area depends on transducer design and focusing.

Energy delivery pattern distinguishes pulsed from continuous. Pulsed ultrasound sends energy in short bursts with off times between them. Those silent intervals mean the energy is not delivered all the time, so the average energy reaching the tissue can be kept lower by adjusting the duty cycle. Continuous ultrasound, on the other hand, emits energy without interruption, delivering energy steadily and thus producing a higher average dose and greater thermal effect at the same peak intensity. The frequency, speed of sound in tissue, and beam size are not defined by whether the emission is pulsed or continuous; frequency is set by the transducer, speed of sound is a tissue property, and beam area depends on transducer design and focusing.