Which of the following reduces the effect of a hot spot?

• A. Moving the soundhead
• B. Increasing the duty cycle
• C. Using continuous ultrasound
• D. Decreasing the frequency

Answer: (A)

Hot spots come from localized heating where ultrasound energy stays on a small tissue area too long or in a way that creates concentrated energy. Moving the soundhead prevents this by distributing the energy over a larger area and reducing the time any one spot is exposed, which lowers the chance of overheating and helps maintain more even heating across the treated region.

Increasing the duty cycle or using continuous ultrasound raises the thermal load, which would make hotspots more likely rather than less. Decreasing the frequency changes how deeply energy penetrates but doesn’t reliably prevent a hotspot at the surface or in a localized area. So, shifting the soundhead to sweep the treatment area directly reduces the risk of a hotspot.