How do X-rays see your bones?

X ray Machines work by creating a beam of radiation that passes through an object (or body part) and hits a "film cassette. The radiation causes a reaction with the interior of the cassette and this reaction produces light which in turn exposes the xray film inside. The film is then developed to show the image.

The amount of energy the beam contains determines how much radiation will go through an object to hit the cassette. This energy level is determined by the person operating the machine and must be calibrated to the size and density of the object being viewed. The x rays will not penetrate dense objects as well as less dense ones, because of this the areas where the beam passed through dense bone will remain unexposed on the film.

To simplify, the x rays are not looking at your bone as much as they are looking at the difference in densities between the bones and the surrounding tissues.