450 Formula Upper Extremity Practice Exam

Ultrasound modes determine whether energy is delivered continuously or in bursts, which drives whether the primary effect is heating or mechanical effects. When energy is transmitted without interruption in continuous mode, tissue absorbs energy steadily, leading to thermal buildup. This heating effect is capable of affecting deeper tissues, especially when using the lower frequency (which penetrates further) and appropriate intensity, so continuous ultrasound is the mode most associated with deep-tissue heating.

Pulsed ultrasound, on the other hand, delivers energy in short bursts with off times, reducing the average energy delivered and thus the amount of heating. The off times also favor mechanical effects like cavitation and microstreaming, which are less about sustained heat and more about tissue interaction at the cellular level. So the statement that continuous provides heating to deep tissues best captures the primary distinction and typical therapeutic use of the two modes.