These distances are then used to generate two-dimensional images of tissues and organs. Using the speed of sound and the time of each echo’s return, the scanner calculates the distance from the transducer to the tissue boundary. When these echoes hit the transducer, they generate electrical signals that are sent to the ultrasound scanner. the boundary between fluid and soft tissue or tissue and bone). The sound waves are reflected back to the transducer by boundaries between tissues in the path of the beam (e.g. When used in an ultrasound scanner, the transducer sends out a beam of sound waves into the body. These materials are able to produce sound waves when an electric field is applied to them, but can also work in reverse, producing an electric field when a sound wave hits them. In most cases, the active elements in ultrasound transducers are made of special ceramic crystal materials called piezoelectrics. Ultrasound waves are produced by a transducer, which can both emit ultrasound waves, as well as detect the ultrasound echoes reflected back. No incisions or cuts need to be made to the skin, leaving no wounds or scars. The advantage of using ultrasound therapies is that, in most cases, they are non-invasive. These destructive, or ablative, functions are made possible by use of very high-intensity beams that can destroy diseased or abnormal tissues such as tumors. Among the modifications possible are: moving or pushing tissue, heating tissue, dissolving blood clots, or delivering drugs to specific locations in the body. Its purpose is to interact with tissues in the body such that they are either modified or destroyed. Therapeutic ultrasound also uses sound waves above the range of human hearing but does not produce images. Functional ultrasound combines information such as the movement and velocity of tissue or blood, softness or hardness of tissue, and other physical characteristics, with anatomical images to create “information maps.” These maps help doctors visualize changes/differences in function within a structure or organ. Anatomical ultrasound produces images of internal organs or other structures. In addition, ultrasound is sometimes used during surgery by placing a sterile probe into the area being operated on.ĭiagnostic ultrasound can be further sub-divided into anatomical and functional ultrasound.
However, to optimize image quality, probes may be placed inside the body via the gastrointestinal tract, vagina, or blood vessels. Most diagnostic ultrasound probes are placed on the skin. Ultrasound probes, called transducers, produce sound waves that have frequencies above the threshold of human hearing (above 20KHz), but most transducers in current use operate at much higher frequencies (in the megahertz (MHz) range). Diagnostic ultrasound is a non-invasive diagnostic technique used to image inside the body.
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