How a CT scanner works

A single X-ray shadow piles your ribs, heart and spine on top of each other. A CT scanner spins an X-ray tube and a curved detector around you a few times a second, capturing about a thousand shadows in every turn. A computer sharpens each shadow and smears it back along the paths the X-rays took, so every spot gets its own number, and slice after slice stacks up into 3D. Every scan image in this Short is computed from one model chest, not drawn by hand.

1. 0:00 Slice by slice, in 3D
2. 0:13 Which is in front?
3. 0:20 Inside the ring
4. 0:32 Shadow after shadow
5. 0:42 Smeared back into a slice
6. 0:58 Every spot's own number
7. 1:09 Slices stack into 3D
8. 1:17 Everything back in place