The beams pass through skin and muscle, but are blocked by the bones and teeth. Their shadows are captured on photographic film and called x-rays.
Examiners sometimes inject substances that give contrast to soft tissues.
These materials include barium, dyes, and radioactive mixtures. X-rays are fairly safe, but excessive use can pose some health risks. The effects of radiation from repeated x-rays collect over a lifetime. Too much exposure can lead to serious illness. These include blood disorders, cataracts, skin problems, and cancer.