You're sort of missing the point but it is a very understandable question and there are no dumb questions, except perhaps "For the third time, what is your name" and, of course"DY...T.". X-rays, and gamma rays, and most any analytical tool using electromagnetic emissions don't really display useable images because it can quantify density. It works more on being able to discriminate between different densities. A diagnostician, or screener for that matter, can see a tumor in normal tissue or a claymore hidden in a pumpkin (and for loops, a claymore is a high explosive shaped anti-personnel weapon, or, if you prefer, a pretty efficient little stove for field rations if you slice off a sliver and light it) because the differing materials cause differing attenuation and/or absorption of the photon mediating the "ray."
For any more, you have to pay tuition. But I work cheap (Sorry Sister Agnes of the Sorrowful Adverbs) and I promise there are no groping gatekeepers to enter the fertile (non-sterile)area of scientific knowledge.
Ooh! "groping gatekeepers." I like it.