Chest X-ray

What is a chest X-ray?

A chest X-ray is a test that uses a small amount of radiation to create an image of the structures within the chest, including the heart, lungs, blood vessels and bones. During an X-ray, a focused beam of radiation is passed through your body, and a black-and-white image is recorded on special film or a computer. The X-ray image that is created looks like a negative from a black and white photograph.

X-rays work because the body's tissues vary in density (thickness). Each tissue allows a different amount of radiation to pass through and expose the X-ray-sensitive film, which results in a shadow image of the organ. Bones, for example, are very dense, and most of the radiation is prevented from passing through to the film. As a result, bones appear white on an X-ray. Tissues that are less dense - such as the lungs, which are filled with air - allow more of the X-rays to pass through to the film and appear on the image in shades of gray.

Why is a chest X-ray used?

A chest X-ray may be used to help diagnose and plan treatment for various conditions, including:

• Lung disorders such as pneumonia, emphysema, tuberculosis and lung cancer
• Heart disorders such as congestive heart failure (which causes the heart to enlarge
• Fractures (breaks) of the bones in the chest, including the ribs and collarbone, as well as breaks in the bones of the upper spine
• Reasons for shortness of breath, a bad or persistent cough, or chest pain

Who performs the test?

A radiology technologist, a skilled medical professional who is trained in X-ray procedures, will perform the test. A radiologist, a doctor who specializes in evaluating X-rays and other radiology procedures, will interpret the X-rays and report the test results to your doctor.

How do I prepare for the test?

There is no special preparation for a chest X-ray. It is important to tell the technologist if you are or may be pregnant. X-rays generally are not used on pregnant women because of the possible risk of radiation exposure to the developing baby. Also, please tell the technologist if you have an insulin pump.

Before the test begins, you will be asked to remove your clothing - usually just from the waist up--and put on a hospital gown. You also will be asked to remove all jewelry and any other objects containing metal (such as eyeglasses and hairpins). This is done because metal can block the image and interfere with the test results.

What happens during the test?

The technologist will cover you from the waist down with a lead shield or apron. This shield protects your pelvic and reproductive organs from exposure to the radiation. The technologist also will position your body against the X-ray film in a way that produces the clearest image. In most cases, chest X-rays are taken from two positions: from back to front (called a posterior-anterior, or PA, view) and from the side (called a lateral view).

For the PA view, you will stand in front of the X-ray unit with your hands on your hips, your shoulders rolled forward and your chin lifted. The technologist will ask you to be very still and hold your breath while the X-rays are passed through your body. (This only takes a few seconds.) It is necessary to hold your breath because movement, which occurs when you breathe in and out, can blur the X-ray image.

For the lateral view, you will be asked to turn to the side, raise your arms over your head and lift up your chin. Again, you will be asked to be still and hold your breath while the exposure is made.

Tell the technologist if you are unable to stand, lift your chin or hold your arms above your head. The technologist will do his or her best to accommodate your needs during the test.

What happens after the test?

After the X-rays are taken, the technologist will process the images. You may be asked to wait a few minutes while the technologist makes sure the X-rays are acceptable; for example, to be sure they are not blurred. If necessary, you may be asked to repeat the test to obtain a clearer image.

The report of your chest X-ray will be sent to your doctor, who will discuss the results with you. In non-emergency cases, results usually are available within a day or two.

How long does the test last?

Plan about 20 to 30 minutes for the test. This includes time for preparation, positioning, processing the films and repeating any images, if necessary.

What will I feel during the test?

A chest X-ray is painless. You will not feel the radiation as it passes through your body. The positions required for the chest X-ray may feel awkward or uncomfortable, but you only have to stay in position for a few seconds. The X-ray room may be cool because air conditioning is used to keep the equipment at a constant temperature.

The film plate also may feel cold.

What are the risks of a chest X-ray?

In general, chest X-rays are very safe and unlikely to produce side effects. The amount of radiation used is very small, so the risks are minimal. Young children and a developing fetus carried by a pregnant woman are more sensitive to X-rays and are at greater risk for tissue damage.