Patient Basics: Chest X-Ray

Originally published by Harvard Health.

What is the test?

Doctors have used x-rays for over a century to see inside the body in order to diagnose a variety of problems, including cancer, fractures, and pneumonia. During this test, you usually stand in front of a photographic plate while a machine sends x-rays, a type of radiation, through your body. Originally, a photograph of internal structures was produced on film; nowadays, the image created by the x-rays goes directly into a computer. Dense structures, such as bone, appear white on the x-ray films because they absorb many of the x-ray beams and block them from reaching the plate. Hollow body parts, such as lungs, appear dark because x-rays pass through them.

Back x-rays and chest x-rays are among the most common conventional x-ray tests. You should not have an x-ray if you’re pregnant unless the risk is considered and special precautions are taken, because radiation can be harmful to a developing fetus.

A chest x-ray provides black-and-white images of your lungs, ribs, heart, and diaphragm.

How do I prepare for the test?

You are usually asked to remove all clothing, undergarments, and jewelry above your waist, and to wear a hospital gown.

What happens when the test is performed?

Chest x-rays usually are taken while you are standing. A technician positions you against the photographic plate (which looks like a large board) to obtain the clearest pictures. He or she takes pictures from the front and from one side while asking you to take in a deep breath just before each picture. The technician leaves the room or stands behind a screen while the x-rays are taken.

What risks are there from the test?

The amount of radiation from x-ray tests is too small to be likely to cause any harm. However, if you’re pregnant, talk to your doctor. Radiation may be harmful to a developing fetus.

Must I do anything special after the test is over?

No.

How long is it before the result of the test is known?

Although digital images may be available immediately, it will take additional time for a doctor to examine and interpret them. You’ll probably get the results later in the day.