One of the key things in looking at x-rays is being able to visualise the anatomy – what does each shadow and each area of whiteness represent anatomically. The x-ray is a rough representation of the anatomy lying under the skin.
The image below is a great example of what you’re really looking at when you look at the CXR. The mediastinum on the CXR looks like a fairly boring blob of white, but what secrets it contains!
via Mike Cadogan on GMEP