Those are lungs seen top down. Those white ovals around the left and right sides sorta hugging the black areas are ribs, the white arrow shape is a vertebrae the hole in it for the spinal cord.
It’s a transverse section so it’s not really ‘top down’ or ‘bottom up’. It’s a thin slice where the densities of the tissue is calculated by sending through X-rays from around the body and measuring how much gets trough from each angle and then letting a computer do some fancy math.
Correct, and I could have used bottom up as the analogy as well, I just think to down since that's the way they go through ct's and mris when I get them done.
My mom had me when I was young and I helped her study when she went back to college for Radiology. I thought this was some really weird joke or something... like she is so dumb she is telling her doctor that it's a brain scan image.