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Derivative of Heath Raftery's own creation. Rough diagram of sound frequency scale, showing ultrasound and some applications. Date: 28 June 2010, 23:30 (UTC) Source: Ultrasound_range_diagram.png; Ultrasound_range_diagram_png_(sk).svg; Author: Ultrasound_range_diagram.png: The original uploader was LightYear at English Wikipedia.
Sound field of a non focusing 4 MHz ultrasonic transducer with a near field length of N = 67 mm in water. The plot shows the sound pressure at a logarithmic db-scale. Sound pressure field of the same ultrasonic transducer (4 MHz, N = 67 mm) with the transducer surface having a spherical curvature with the curvature radius R = 30 mm
The ratio of the imaging depth to the aperture size is known as the F-number. Dynamic aperture is keeping this number constant by growing the aperture with the imaging depth until the physical aperture cannot be increased. A modern medical ultrasound machine has a typical F-number of 0.5.
Ultrasound is sound with frequencies greater than 20 kilohertz. [1] This frequency is the approximate upper audible limit of human hearing in healthy young adults. The physical principles of acoustic waves apply to any frequency range, including ultrasound.
Ultrasound energy, simply known as ultrasound, is a type of mechanical energy called sound characterized by vibrating or moving particles within a medium. Ultrasound is distinguished by vibrations with a frequency greater than 20,000 Hz, compared to audible sounds that humans typically hear with frequencies between 20 and 20,000 Hz.
Sound from ultrasound is the name given here to the generation of audible sound from modulated ultrasound without using an active receiver. This happens when the modulated ultrasound passes through a nonlinear medium which acts, intentionally or unintentionally, as a demodulator .
Medical ultrasound includes diagnostic techniques (mainly imaging techniques) using ultrasound, as well as therapeutic applications of ultrasound. In diagnosis, it is used to create an image of internal body structures such as tendons, muscles, joints, blood vessels, and internal organs, to measure some characteristics (e.g., distances and velocities) or to generate an informative audible sound.
Mechanical index (MI) is a unitless ultrasound metric. It is defined as [1] =, where P r is the peak rarefaction pressure of the ultrasound wave , derated by an attenuation factor to account for in-tissue acoustic attenuation; f c is the center frequency of the ultrasound pulse .