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Time gain compensation (TGC) is a setting applied in diagnostic ultrasound imaging to account for tissue attenuation. [1] By increasing the received signal intensity with depth, the artifacts in the uniformity of a B-mode image intensity are reduced.
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.
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.
Although ultrasound does not traditionally exhibit the high resolution of MRI or CT, high-frequency ultrasound (HFU) achieves relatively high resolution by sacrificing some penetration depth. [2] HFU typically uses waves between 20 and 100 MHz and achieves resolution of 16-80μm at depths of 3-12mm. [2]
For example, the speed of sound in water is 1,497 m/s, and the human body is about 0.5 m thick, so the PRF for ultrasound images of the human body should be less than about 2 kHz (1,497/0.5). As another example, ocean depth is approximately 2 km, so sound takes over a second to return from the sea floor.
By changing the pulse delays, the computer can scan the beam of ultrasound in a raster pattern across the tissue. Echoes reflected by different density tissue, received by the transducers, build up an image of the underlying structures. Weld examination by phased array. TOP: The phased array probe emits a series of beams to flood the weld with ...
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Ultrasound Localization Microscopy (ULM) is an advanced ultrasound imaging technique. By localizing microbubbles, ULM overcomes the physical limit of diffraction, achieving sub-wavelength level resolution and qualifying as a super-resolution technique.