Factors affecting the appearance  


Do you know what the above radiographs are of? That on the left is taken from above and that on the right from the side. It is an artichoke, and has quite a complex appearance on radiography. Note that the outermost leaves, which can be seen in isolation, are very lucent, except at the tips where they curl in somewhat and appear denser due to some overlap. The choke, or center of the artichoke is the whitest area, due to its density and thickness in comparison to the fine leaves. The image taken from the side shows the air intervening between the leaves.