The Physics of Ultrasound

Abstract

Clinical ultrasound has attained significant importance for the practising anesthesiologist. Its applications reach far and wide in anatomic and physiologic diagnosis, and it is a powerful adjunct for guiding interventional procedures. This article describes the physical principles that allow for the generation of ultrasound, its transmission and reflection from within the body, and generation of the ultrasound images used in daily practice. We not only review definitions of important technical terms but also provide synonyms in plain language, as jargon often presents a barrier to grasping basic and fundamental principles. Furthermore, we review the mathematical and physical principles that facilitate the generation of Doppler modes, such as pulsed wave, continuous wave, color flow. Clinically safe practice requires that all data be interpreted in the light of the technology’s shortcomings; we additionally review the common pitfalls and artifacts encountered in the use of this imaging modality. This review contains 16 figures, 1 table, and 5 references. Keywords: attenuation, continuous wave Doppler, Doppler, frequency, imaging artefacts, physics, pulsed-wave Doppler, ultrasound