X-ray machines in the radiology department of a hospital. At left is a chest X-ray machine, which is used with the patient in a standing position. At centre right is an X-ray machine with a bed that can tilt and swivel. The box above the bed emits X-rays onto a patient lying on the bed. The X-rays pass through the patient and cast an image onto film positioned beneath the bed (in box with control panel. X-rays are electromagnetic rays that can penetrate soft tissues, but are absorbed by bones or opaque contrast media, and can therefore be used to diagnose internal injuries and disorders.