In medicine, “imaging” is the term used for any method to take pictures of bones and organs inside the body. Many imaging modalities use x-ray radiation whichcan help your health care provider find the cause of a medical problem. For example, x-rays may be used to find a tumor, kidney stones , or a developmental problem.
An x-ray (or conventional radiology) is a form of radiation produced by special machines that take pictures of the inside of your body. Structures that are dense, like bones, look white on the film. Structures that contain air, like your lungs, look black. Muscle, fat and fluid appear as different shades of gray.
Since soft tissues, like the kidneys, ureters, and bladder are not easily seen with x-ray, contrast agents or dyes can be used to help identify those structures. These dyes are injected directly into the organ or into a vein before the x-ray is taken. The dye helps your doctors see the shape of the urinary tract and soft tissue organs better on film.