ARDMS Ultrasound Physics & Instrumentation Practice Exam 2025 - Free Ultrasound Practice Questions and Study Guide

To determine the total amount of attenuation when a 6.0-MHz sound beam travels through 4 cm of soft tissue, one must understand the principle of attenuation in ultrasound. Attenuation occurs due to the absorption, reflection, and scattering of sound waves as they pass through a medium. In soft tissue, a common rule of thumb is that there is approximately 0.5 dB of attenuation per MHz per centimeter of travel.

For a 6.0-MHz frequency sound beam traveling through 4 cm of soft tissue, you can calculate the total attenuation as follows:

1. Calculate the attenuation per centimeter: 0.5 dB/MHz/cm.

2. Multiply this by the frequency: 0.5 dB/MHz/cm * 6 MHz = 3 dB/cm.

3. Then multiply by the depth of tissue: 3 dB/cm * 4 cm = 12 dB.

Therefore, the total amount of attenuation is 12 dB. This calculation highlights how the frequency and the distance traveled through a medium contribute to the overall attenuation experienced by the ultrasound wave in soft tissue.