X-rays focus radiation on one area of the body in order to create a visible image. A wavelike form of electromagnetic energy, X-rays work using energy beams of very short wavelengths, which are undetectable to the human eye. Because X-rays are two-dimensional images, many images from varying angles may be required for an accurate diagnosis.
When X-ray radiation passes through your body, it is absorbed by solid objects. The density of the object determines whether the area will appear black, white, or gray on the image. Dense, hard structures such as bone appear white; X-ray images taken where there is air, such as in the lungs, will appear black. Soft tissues such as fat, skin, and muscle appear in shades of gray.
Because X-rays can identify bony structures, they are useful in examining the pathology of the skeletal system. As well, they can detect some disease processes in soft tissue such as pneumonia, lung cancer, pulmonary edema, and intestinal blockages.