Physics 2000 Einstein's Legacy CAT Scans

Rib Cage Projection

Does this really work on things more complicated than simple boxes?

Let's try this again using a model of a rib cage for the object.

Um...that's supposed to be a rib cage?

Use your imagination, Alex.

  1. Press the "Scan" button to make a single scan.
  2. Now click and drag the figure on the left to turn it. (Give the computer a few seconds to catch up with you...)
  3. Press "Scan" again...this time the new scan gets averaged into the previous one.
  4. Continue to turn and scan. If you space your scans evenly you will get the clearest results. 30 degree increments should work well.
  5. If you want the computer to do all the work, click here.

I don't get it. What's going on in that window on the right?

When we make a scan, the x-ray shadow (in the middle window) gets "projected" or "smeared out" in the window on the right. When we turn our object, the window on the right turns, too. Then, when we make another scan the new projection gets averaged in with whatever is already there.

Oh, yeah, just like when we added those two pictures together a few minutes ago.

Exactly, except here we can add as many shadows as we want. When we're done, we have one "slice" of the picture.

Then we can make more slices, stack them all up, and get a full 3D picture of the inside of something!