What Is It X-Rays?

X-rays are waves of electromagnetic radiation that are used to create images of organs and other structures inside the body. X-rays have a very short wavelength. As they penetrate the body, they are absorbed in different amounts by different body tissues. For example, bones are dense and absorb X-rays very well, but soft tissues (skin, fat, muscle) allow more X-rays to pass through. The result is an X-ray shadow on a film or fluorescent screen, where images of bones appear white, while shadows of soft tissues appear as various shades of gray.

In some forms of X-rays, a chemical called contrast medium is given to the patient to help outline a specific body area on X-ray film. This chemical can be swallowed, given as an enema or injected into a vein. The contrast medium appears white on the X-ray film, and can produce a sharp outline of structures such as the digestive tract and the paths of blood vessels.

While X-rays themselves are painless, there may be some mild discomfort from a pin prick or from an enema if contrast medium is used. Some X-rays take less than a minute, while longer X-ray procedures may take an hour or more.

What It"s Used For

X-rays are used for many purposes, including determining if a bone is broken, seeing whether an internal organ is infected, and looking for cancer. There are many different types of X-rays currently used to detect cancer. For example, both mammography (a series of breast X-rays) and the barium enema (a series of bowel X-rays with contrast medium), are routine procedures sometimes used for cancer screening in adults of certain age groups. To check for tumors in precise cross-sections of the body, a computed tomography (CT) scan also can be used. A CT scan is a series of X-rays linked to computer technology. Even without using specialized techniques, uncomplicated, routine X-rays often can show abnormal shadows or silhouettes that might be cancerous tumors.