Physics and Knobs

Understanding the physics of ultrasonography may seem like an unnecessary endeavor but having a solid understanding of what is behind the image can help you acquire the optimal image as well as correctly interpret the image. Ultrasound waves are mechanical waves which are at a frequency above the range of human hearing. They are sent into tissue and are returned through the transducer, allowing the machine to interpret what is returned. Doppler factors in frequency shifts to determine movement and direction. Adjusting the frequency affects the resolution and the penetration into the tissue, whereas adjusting the gain affects the amplitude of the signal returning to the transducer. There are numerous artifacts that are crucial to identifying pathology, recognizing normal anatomy and guiding image acquisition. Lastly, when performing a procedure, consider keeping probe marker and indicator on the same side to avoid confusion.