Energy transmission in ultrasound relies on density changes during which phases?

Energy transmission in ultrasound relies on density changes during which phases?

• A. Only high density changes
• B. Only low density changes
• C. Low and high density changes
• D. No density changes

Answer: (C)

Ultrasound energy propagates as a longitudinal wave, meaning the particles in the medium oscillate back and forth in the direction of travel. This creates alternating regions of compression, where density and pressure momentarily rise, and rarefaction, where density and pressure fall. The energy is carried by these successive density changes as the wave moves through tissue. If only one phase occurred, there would be no continuous wave to transfer energy. So, energy transmission relies on both high-density changes (compressions) and low-density changes (rarefactions)—not just one or none.

Ultrasound energy propagates as a longitudinal wave, meaning the particles in the medium oscillate back and forth in the direction of travel. This creates alternating regions of compression, where density and pressure momentarily rise, and rarefaction, where density and pressure fall. The energy is carried by these successive density changes as the wave moves through tissue. If only one phase occurred, there would be no continuous wave to transfer energy. So, energy transmission relies on both high-density changes (compressions) and low-density changes (rarefactions)—not just one or none.