ABSTRACT
Echocardiography uses ultrasound to examine the structure and function of the heart. A firm understanding of the physics of ultrasound gives the sonographer:
● an understanding of the capabilities and limitations of their echo machine
● Elementary physics Sound travels as a longitudinal mechanical wave, and can be thought of as a series of vibrating particles in a line. Unlike electromagnetic waves (e.g. light waves, radio waves), sound waves need the presence of particles to be transmitted – sound cannot travel though a vacuum but instead requires a medium such as air, water or a solid. When a sound wave travels through a medium, there are areas of compression (high pressure and density, where the particles are closer together) and rarefaction (low pressure and density, where they are further apart). Sound can be represented as a sine wave, showing the variation in pressure through the medium (Fig. 3.1).
