About Diagnostic Radiography (X-ray)

Radiography, commonly known as X-ray, was discovered more than a century ago. It is the most frequently used method of medical imaging.

X-rays are a type of invisible electro-magnetic radiation and create no sensation when they pass through the body. Modern X-ray techniques use only a fraction of the X-ray dose that was required in the early days of radiology.

When passed through human tissue, some of the X-rays are absorbed by the body. Once their energy is absorbed, no residual radiation remains—your body does not become “radioactive” from having an X-ray exam. The amount of X-ray energy absorbed depends on the density of the tissue; because bones are hard, they absorb more X-rays, leaving fewer to strike and expose the film underneath. Thus, bones appear white on an X-ray image. Air, such as in the lungs or bowel, is not dense at all. Consequently, most of the X-ray energy passes through air-filled areas, exposing the film and making it appear black. The organs and muscles and other tissues appear as varying shades of gray.

Because many of the internal structures are similar in density, discerning different shades can be difficult. When your doctor needs information about an internal organ, a contrast medium, or “dye,” may be used for your exam. Contrast medium is dense and therefore makes any structure into which it flows appear white or lighter on the image.

Most X-ray exams require two or more views to be taken. Examination of some internal organ structures requires multiple images, from different angles. Radiography is a highly regulated medical specialty, because radiation may cause side effects. All of the technologists at Marquis Diagnostic Imaging who perform radiology exams have undergone at least two years of special training, are licensed in the state of Arizona, and must continue to take courses to renew their licenses every two years.