Ultrasound waves are beyond the level of human hearing and are used medically for non-invasive testing and measurement. Ultrasound wave frequencies technically start at about 20kHz, but most ultrasonic transducers start at 200kHz. With very short wavelengths, ultrasound is good for detecting small details.
Electrical energy is transformed into ultrasonic energy, and the waves are projected into the body. The reflection and scattering caused by tissue and structures within the body are returned as echoes and examined, known as pulse-echo ranging, and is very similar to sonar and radar technology. Ultrasound can be used to measure the flow and velocity of fluids in real time using principles of the Doppler effect, and are displayed to the operator as colored overlays.
Ultrasound has experienced innovation in electronics integration and in down-sizing the implementation of power, resulting in more portable and efficient ultrasound systems with improved image performance and more functionality. Higher dynamic range, lower power, and more compact system-level ICs provide high quality images that allow for better diagnoses. After 50 years of use and development, Ultrasound Imaging is now capable of 3D real-time imaging with powerful, high performance processors which is especially valued in cardiology. Ultrasound systems may evolve into everyday use as handheld devices, much like the stethoscope is used by doctors today.