Introduction

Radiography, known to most people as x-ray, uses electromagnetic radiation to make images of bones, teeth and internal organs. X-rays allow doctors to take pictures of the inside of your body.

One of the oldest forms of medical imaging, x-ray is a simple, painless medical test that can help your doctor provide you with appropriate treatment. It's a fast, easy and safe way for your doctor to view and assess conditions ranging from broken bones to pneumonia to cancer. Many different types of x-rays, such as bone or chest x-rays, exist. The type your doctor uses depends on what part of your body needs examining and for what purpose.

Uses of X-rays

• Determine whether a bone is chipped, dislocated or broken (fractured)
• Evaluate joint injuries and bone infections
• Diagnose and monitor the progression of degenerative conditions, such as arthritis and the bone-thinning disease osteoporosis
• Screen for lung and heart diseases
• Find and treat artery blockages
• Diagnose the cause of persistent coughing or chest pain
• Check for broken ribs or a punctured lung
• Evaluate unexplained abdominal pain
• Help locate objects that may have been accidentally swallowed by a child
• Determine whether you have injured a bone or disk in your spine
• Detect scoliosis, an abnormal curvature of the spine, and other spinal defects
• Evaluate infection of the sinuses (sinusitis)
• Locate dental problems such as cavities, abscessed teeth and other tooth and jaw abnormalities
• X-ray exams also play an important role in the detection and diagnosis of cancer. In fact, one use of x-ray in diagnosing cancer is to see whether you have lung cancer or whether cancer from another part of the body has spread (metastasized) to the lungs. Cancer may appear lighter in color on X-ray films than does normal, healthy lung tissue. X-rays may also be used to examine cancers of the intestines, stomach, liver, spleen, kidneys and breasts.

Preparing for an X-ray

Different types of x-rays require different preparations. In general, you undress the area of your body that needs examination. You may wear a gown to cover yourself during the exam, depending on what area is being x-rayed. You may also be asked to remove jewelry, eyeglasses and any metal objects that could, like clothing, obscure the x-ray image.

You may wear a lead apron to shield your sex organs from exposure to x-rays. At very high doses, radiation can damage a woman's eggs or a man's sperm. Since you're exposed to a small amount of radiation during most x-rays, the lead apron is used simply as a precaution.

At high doses, radiation also can be harmful to a fetus. Always inform the x-ray technologist if there's any possibility that you are pregnant. Your doctor may suggest you either forgo the x-ray exam or, if one is necessary at the time, take precautions to minimize radiation exposure to the fetus.

Before some types of x-rays, such as a barium enema, you're given a liquid called contrast medium, or a dye. Contrast mediums help outline a specific area of your body on x-ray film. You may swallow the contrast medium, insert it as an enema or receive it as an injection into a vein. Contrast medium appears opaque on x-ray film, providing a clear outline of structures such as your digestive tract or blood vessels.

If you're to receive a contrast medium before an x-ray, tell your doctor if you have a history of allergy to x-ray dye.

How X-rays Work

X-rays are a form of energy or radiation. X-rays exist in nature, emanating from outer space, rocks and even the soil. You cannot see or feel x-rays. Because they're of higher energy than visible light, x-rays can penetrate objects, including your body.

An x-ray machine produces an x-ray beam using an x-ray tube carefully aimed and focused on the body part being examined. The machine produces a tiny burst of radiation, at a safe level, that passes through your body and produces an image on film or on a TV or computer screen.

As x-rays pass through your body, different tissues absorb different amounts. For example, your bones are dense and absorb x-rays well. But soft tissues, such as your skin, fat, muscles and organs, allow more x-rays to pass through them. The result is that bones appear white on the x-ray. Your other tissues appear in varying shades of gray. Structures containing air, such as your lungs, appear black.

What You Can Expect During an X-ray

X-rays are performed at most doctors' offices, dentists' offices, emergency rooms and hospitals. You may lie on a table, sit or stand between the x-ray machine and the x-ray film. The technologist helps position your body to obtain the necessary views. He or she may use pillows or sandbags to help you hold the proper position. The technologist then aims the machine at the area of your body that needs examination. Once you're in the proper position, the technologist enters a control booth. During the xX-ray exposure, you remain still and hold your breath to avoid moving, which can cause blurring on the film.

The technologist may take x-rays from multiple angles.

If your young child is having an x-ray, restraints may be used to help keep him or her still. You may be allowed to remain with your child during the test. If you remain in the room during the x-ray exposure, you're typically given a lead apron to wear to shield you from unnecessary exposure.

An x-ray procedure may last from several minutes, for a bone x-ray, to about an hour, for more involved procedures such as those using a contrast medium.

For most x-rays, you feel no discomfort other than the hardness of the x-ray table or the temperature of the room, which may be kept cool to keep the equipment from overheating. It may be necessary to compress momentarily the body part being examined. This compression may be uncomfortable, but the discomfort lasts only briefly during the x-ray exposure. If you're having a test that requires contrast medium, ask your doctor what to expect.

After an x-ray, you generally dress and return to your normal activities. Routine x-rays usually have no side effects. However, if you receive an injection of contrast medium before your x-rays, call your doctor if you experience pain, swelling or redness at the injection site. Ask your doctor about other signs and symptoms to watch for pertaining to your specific x-ray procedure.

You may worry that x-rays are not safe because it is known that high levels of radiation exposure can cause cell mutations that may lead to cancer. But the amount of radiation that you are exposed to during an x-ray is so small that the risk of any damage to cells in your body is extremely low. Thus, for most x-ray examinations, the benefits of any medically indicated examination are thought to greatly outweigh the small risk. In addition, great care is taken to use the lowest radiation dose possible to produce the best image for the radiologist to evaluate. No radiation remains after an x-ray examination.

However, if you're pregnant or suspect that you may be pregnant, inform your doctor before having an x-ray. Though the risk of most diagnostic x-rays to an unborn baby is small, your doctor may consider whether it's better to wait or to use another imaging test such as ultrasound.