This term, I really got into enoyed learning about artifact in physics. I used to think artifacts were mistakes or "bad scans," but I've discovered that they're actually normal effects of how sound interacts with tissue. Artifacts emerge when the ultrasound machine's assumptions are wrong. For example, it can think that sound travels in a straight line, at a constant speed, and only reflects once before going back to the transducer. Artifacts appear on the image when those assumptions are wrong. Posterior acoustic enhancement is a very typical phenomenon that we observe all the time. When sound goes through a structure that is full of fluid, like the gallbladder or a simple cyst, something happens. Because fluid absorbs less sound, more echoes come back from the tissue behind it, making that area look brighter. This artifact is useful and can aid make a diagnosis of a cystic formation. On the other hand, acoustic shadowing happens when sound hits a structure that absorbs a lot of sound, such a gallstone or bone. Because the sound can't get through, the area behind it looks dark. Shadowing is another artifact that assists us because it lets us confirm things like calculi