X-ray imaging is used to view internal structures and organs. It's frequently used to examine bones, teeth, or breasts, or to diagnose tumors. A standard X-ray is produced by placing a particular part of the body before a sheet of film, then exposing that area to radiation from an X-ray tube. As the X-rays pass through the body, they generate images. Dense material like bone absorbs most of the rays, and shows up as white areas. Soft tissue allows X-rays to pass easily, showing up as black areas. The images are recorded onto the film, or captured as a moving image on a screen. When a picture is required of soft structures like arteries, a contrast material that shows up on X-ray can be introduced. Or, a liquid may be taken by mouth, as in a barium (BEAR-ee-um) X-ray, which illuminates the gastro-intestinal tract. Though X-rays are invisible and can't be felt, large doses can be harmful. Therefore, you may be covered with a lead (led) apron to protect areas of the body not being imaged. A newer garment uses latex and a metal called bismuth (BIZ-muth) to reduce radiation exposure, while still allowing a picture to be made. However, pregnant women shouldn't get an X-ray without consulting a doctor first. To learn more about X-rays, speak to a health care professional.