Summary of Basic Ultrasound Physics for EM

00:00:00 - 00:15:00

Ultrasound is a technology that uses sound to create images of the inside of the body. The sound waves are reflected back to the transducer, which creates a very bright image. However, the sound waves are highly attenuated, meaning that they are reflected back before they reach the far side of the object being imaged. This results in an image with a lot of white space, which can be difficult to interpret.

• 00:00:00 Ultrasound is a mechanical pressure wave that is used to image body structures. The basics of ultrasound physics are reviewed, including the definition of ultrasound, the reverse piezoelectric effect, the piezoelectric effect, the pulse echo principle, the echo range principle, the attenuation of sound, reflection, and scattering. Modes of ultrasound are discussed, including B mode or brightness mode, motion mode, and color Doppler.
• 00:05:00 Ultrasound technology is used to see inside the body and produce images of organs and tissues. There are several types of transducers used, with different frequency ranges and resolutions. Ultrasounds can produce artifacts such as sound waves that don't travel in a straight line, which can be broken down into shattering and compression artifacts.
• 00:10:00 Ultrasounds use sound to create images of the body. Ultrasound is highly attenuated, meaning that the sound beam is reflected back to the transducer making a very bright image but no sound is transmitted past that interface. You can see here in the gallstone we can see the brain interface where the sound beam is reflected from the gallstone. The gall stones not calcified but it can have very high acoustic impedance compared to the tissue around it and therefore sound does not penetrate further and this area highlighted in black would be the area of acoustic shadow meaning that sound does not transmit it past that surface. You can see here as we scan through a gallbladder with multiple stones you can see the area where the stones are and the sound beam is reflected back to the probe with shadowing behind posterior acoustic enhancement occurs when there's a very low attenuating circle and this occurs when there is a fluid interface. Now the fluid does not interact with sound beam as it does with solid tissue and therefore the sound beam is not weakened so the sound being remains very strong so when that echo returns from behind the fluid structure it has not been attenuated as greatly as that they travel through tissue the ultrasound machine interprets this as a greater signal and makes those images brighter
• 00:15:00 Ultrasound images are composed of echoes, which indicate the amount of whiteness within the image. Echogenicity is a relative scale, and in this video, the narrator discusses some ultrasound terminology used to describe images. For example, the collapse lung and spleen are described as being I select to each other.