An ultrasound scanner is a machine that creates images of the internal tissues/organs of the body for diagnostic and therapeutic purposes. It works by sending high frequency sound pulses (higher than sound waves audible to the human ear, >20,000 Hz) into the patient’s body. These sound waves travel through the body and pass through different tissues at different speeds (for example, 1540 m/s for fat tissue and 4080 m/s for bone). When sound encounters two adjacent tissue types with different acoustic properties, a fraction of the sound energy is reflected. A computer inside the ultrasound scanner receives the sound energy reflected and uses them to create an image, which is displayed on a screen as a two-dimensional (2D) image. Ultrasound images are displayed using a grey scale.
A typical ultrasound scanner consists of a transducer probe (which produces the sound waves and receives the echoes), transducer pulse controls (that allows the operator to alter the length and frequency of sound pulses), a central processing unit (which processes the data to create the final image), a display (usually a high definition computer monitor), a keyboard and cursor (to add notes to the images), a disc storage (to store scans digitally), and a printer.