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X-Ray

X-rays are a form of radiation, like light or radio waves, that can be focused into a beam, much like a flashlight beam. Unlike a beam of light, however, X-rays can pass through most objects, including the human body. When X-rays strike a piece of photographic film, they can produce a picture. Dense tissues in the body, such as bones, block (absorb) many of the X-rays and appear white on an X-ray picture. Less dense tissues, such as muscles and organs, block fewer of the X-rays (more of the X-rays pass through) and appear in shades of gray. X-rays that pass only through air appear black.

A spinal X-ray test provides a picture of the bones that make up the spine (vertebrae). The spine is a column of 33 bones, which are divided into five groups from the neck to the tail bone. These groups are:

• 7 neck (cervical) vertebrae.
• 12 chest (thoracic) vertebrae.
• 5 lower back (lumbar) vertebrae.
• 5 small, fused vertebrae (the sacrum).
• 4 small, fused vertebrae (the coccyx).

Why It Is Done

• Determine the extent of injuries to the bones of the spine (vertebrae).
• Help determine the cause of persistent pain, numbness, or weakness.
• Detect spinal fractures, dislocations, tumors, bone spurs, or disc disease.
• Evaluate arthritis of the spinal bones.
• Evaluate abnormal curvatures of the spine (such as scoliosis) in children.
• Evaluate the spine in infants suspected or known to have a spinal defect (such as spina bifida).
• Monitor changes in the spine after spinal surgery

How to Prepare

Before the X-ray test, tell your doctor if:

• You might be pregnant. A spinal X-ray is not usually done for a pregnant woman because the radiation could damage the fetus developing inside her. However, the chance of harm to the fetus is usually very small, and the benefits of having the test may outweigh the potential risks.
• You have undergone an X-ray test using barium contrast material (such as a barium enema) within the past 4 days. Barium shows up on X-ray films and can interfere with the results of a lower back (lumbar spine) X-ray.
  

How It Is Done

A spinal X-ray is taken by a radiology technologist. The X-ray pictures are usually interpreted by a doctor who specializes in evaluating X-rays (radiologist). However, some other types of doctors can also review spinal X-ray pictures for common problems, such as disc disease, a spinal fracture, or arthritis.

You will need to remove jewelry that might interfere with the X-ray picture. You may need to take off some or all of your clothes, depending on which area is examined (you may be allowed to keep on your underwear if it does not interfere with the test). You will be given a cloth or paper covering to use during the test.

During the X-ray test, you will lie on an X-ray table. You will be placed in different positions to obtain the needed views. If the X-ray is being taken because of a possibly serious injury to your neck or back, a radiologist will review the first pictures to prevent further injury before taking others. If you have a neck brace (cervical collar) in place, X-ray pictures may be taken and used along with a physical exam to determine if the brace can be removed without damaging the spine.

Usually 3 to 5 X-ray pictures are taken. You need to lie very still to avoid blurring the pictures. A spinal X-ray usually takes about 15 minutes. You will be asked to wait (usually about 5 minutes) until the X-rays are developed in case repeat pictures need to be taken. In some clinics and hospitals, X-ray pictures can be produced immediately on a computer screen (digitally). This will shorten the waiting time.

How It Feels

You will feel no discomfort from the X-rays. However, the X-ray table may feel hard and the room may be chilly because air-conditioning is used to keep the X-ray equipment at a constant temperature. You may find that the positions you need to hold are uncomfortable or painful, especially if you have an injury.

Risks

There is always a slight risk of damage to cells or tissue from being exposed to any radiation, including the low levels of X-rays used for this test. However, if this test is really needed, the risk of damage from the X-rays is usually very low compared with the potential benefits of the test. There are precautions you can take to reduce your risk of radiation exposure from X-rays

Results

In an emergency, the results of a spinal X-ray can be available within a few minutes. Otherwise, results are usually ready within a day.