Which ultrasound parameters produce purely nonthermal effects?

The parameters that produce purely nonthermal effects in ultrasound therapy are characterized by low intensity combined with a low duty cycle.

When using ultrasound in a therapeutic context, nonthermal effects are primarily associated with mechanical and biochemical changes at the cellular level rather than an increase in temperature. Low intensity minimizes the heating effects caused by ultrasound waves, while a low duty cycle indicates that the ultrasound is on for a smaller percentage of the treatment time compared to being off. This combination allows for the mechanical effects of ultrasound, such as cavitation and microstreaming, to influence tissue healing without generating significant heat.

In contrast, a high intensity setting typically increases the likelihood of thermal effects occurring, as it delivers more energy to the tissues, raising their temperature. Additionally, a high duty cycle keeps the ultrasound on for a larger portion of the treatment time, further promoting heat production. Therefore, options that involve either high intensity or high duty cycle are less likely to result in purely nonthermal outcomes.

Thus, low intensity and a low duty cycle are specifically designed to achieve the desired nonthermal effects in therapeutic ultrasound.