Continuous ultrasound versus pulsed ultrasound in terms of thermal effects?

• A. Non-thermal/mechanical effects
• B. No effect
• C. Electrical effects
• D. Thermal effects

Answer: (D)

Continuous ultrasound delivers energy without interruption, so tissue absorbs energy steadily and temperature rises over the treatment time. This sustained energy deposition leads to measurable thermal effects, which is why continuous mode is associated with heating. Pulsed ultrasound, with on and off cycles, allows heat to dissipate during the off periods, reducing overall temperature rise and making non-thermal, mechanical effects (like microstreaming and cavitation) more prominent at typical therapeutic settings. So, when talking about thermal effects, continuous ultrasound produces more heating than pulsed, making thermal effects the best description for continuous delivery.