Which ultrasound safety index gauges heating potential?

• A. Thermal Index
• B. Focal Index
• C. Range Index
• D. Mechanical Index

Answer: (A)

Understanding how ultrasound safety is monitored hinges on recognizing what each index reflects. The Thermal Index measures how much the ultrasound beam could raise tissue temperature during exposure. It translates the power, exposure time, and tissue attenuation into an estimated temperature rise, helping clinicians keep heating within safe limits. Machines may display different forms of the Thermal Index (soft tissue, bone, and cumulative), but the core idea is the same: it gauges heating potential.

In contrast, the Mechanical Index assesses mechanical effects like cavitation and other non-thermal bioeffects, not temperature rise. The other terms listed aren’t standard indices for heating at all, so they don’t serve as measures of heating potential.