What defines the attenuation coefficient of sound in soft tissue?

The attenuation coefficient of sound in soft tissue is defined as the frequency of the sound wave divided by a constant, typically expressed in dB per centimeter per megahertz. As the frequency of the ultrasound increases, the attenuation coefficient also increases, which means that higher frequency ultrasound waves will experience more attenuation as they travel through soft tissue. The relationship is approximately linear, where the attenuation coefficient is roughly equal to the frequency in megahertz divided by 2.

This understanding is vital in ultrasound imaging because it helps sonographers choose appropriate frequencies for imaging different tissues while considering the trade-off between resolution and depth of penetration. Higher frequencies provide better resolution but penetrate less deeply due to increased attenuation, while lower frequencies penetrate deeper but have poorer resolution. Knowing the relationship encapsulated in dividing the frequency by 2 allows practitioners to plan and optimize their imaging techniques effectively.