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RE: ASK ME PHYSICS: Questions on physics answered
I've always wondered how ultrasound is capable of giving us a two dimensional image.... If i was to use a sound wave to map an object from on top would I not simply get a general idea of the density of the object as a whole (like X-ray)? How's it able to look at different densities at different depths and create an image?
I'm guessing you mean a 3 dimensional image for ultrasound? x rays give a 2 dimensional image. I'll get on it now
With ultrasound there is an A-Scan and a B-Scan, where B-Scans are just multiple A-Scans together.
The basic principle is to scan at a specific location and you receive a 1-D -Signal which consists of only signal peaks (reflections, which is the starting signal shifted in time and attenuated of course).
You then move your ultrasonic device a few millimeters to either side and do the same again. You can then put all of those 1-D signals side by side basically and receive a 2-D Picture (or signal).
Of course these are just the basics and im not an ultrasonic expert, so I can not tell you how specifically ultrasonic methods for medical imaging work (how they generate a 2D picture seemingly instantly).