X-Rays

What Is It?

X-rays are waves of electromagnetic radiation that are used to form images of 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 introduced into the body 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 a variety of 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 in cancer detection. 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.

Preparation

There are many different types of X-ray procedures, and some require special preparation. For example, before having X-rays of your digestive tract, you may need to modify your diet, fast entirely or use laxatives or enemas. Before having mammography, you must avoid the use of deodorants, body powders, perfumes and body creams, which can produce abnormal shadows in the mammogram image. You should remove all jewelry from the part of your body to be X-rayed.

X-rays can affect a developing fetus. If you are a woman and there is a chance that you might be pregnant, tell your doctor before you have an X-ray.

How It's Done