What does pulsed ultrasound imply?

What does pulsed ultrasound imply?

• A. Anything below 100%
• B. 100% duty cycle
• C. Nonthermal only
• D. High frequency

Answer: (A)

Pulsed ultrasound is delivered in bursts with brief pauses between them, so the energy is on only part of the time. The fraction of time the energy is on is called the duty cycle, and for pulsed ultrasound that duty cycle is less than 100%. That’s why the best description is anything below 100%—the key feature distinguishing pulsed from continuous ultrasound. The other ideas miss this pattern: 100% duty cycle would mean continuous ultrasound with no pauses; pulsed ultrasound isn’t restricted to nonthermal effects—both thermal and nonthermal effects can occur depending on the on/off timing and intensity; and frequency refers to the pitch of the ultrasound rather than the on/off pattern, so pulsing isn’t defined by high frequency alone.

Pulsed ultrasound is delivered in bursts with brief pauses between them, so the energy is on only part of the time. The fraction of time the energy is on is called the duty cycle, and for pulsed ultrasound that duty cycle is less than 100%. That’s why the best description is anything below 100%—the key feature distinguishing pulsed from continuous ultrasound.

The other ideas miss this pattern: 100% duty cycle would mean continuous ultrasound with no pauses; pulsed ultrasound isn’t restricted to nonthermal effects—both thermal and nonthermal effects can occur depending on the on/off timing and intensity; and frequency refers to the pitch of the ultrasound rather than the on/off pattern, so pulsing isn’t defined by high frequency alone.