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CT scans dose patients with much more radiation than X-rays

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Posted: Thursday, May 5, 2011 3:30 am

Know the risk before you take the test

CT scans dose patients with much more radiation than X-rays

Consuelo H. Wilkins, MD

Medical accuracy editor

In today's technologically advanced world where movies are downloaded in minutes and aerial views of your backyard are available online, many consumers want their health concerns diagnosed using the latest medical equipment. They also want the quickest treatment available and prefer to take one small pill, one time, and have everything cured.

One of the most common requests that patients make of their doctors is a request for an X-ray or some other imaging test such as a CT scan or MRI. Lately, patients are less likely to request an X-ray but instead request one of the more expensive tests. Perhaps a more expensive test is thought to be better. Although this may be the case for some computers, televisions, cars and furniture, the cost of a health care test or treatment doesn't necessarily have anything to do with its usefulness. In some cases, the more expensive tests or treatments can be harmful.

During the past decade, health care providers and patients have become more cautious regarding the overuse of antibiotics. We have learned that using antibiotics for the common cold and other viral infections is not only ineffective but can lead to infections caused by bacteria that are resistant to the usual antibiotics.

With the availability of special imaging tests such as CT scans, some patients think they should skip a plain X-ray and go for a CT scan. They are often unaware that just like unnecessary antibiotics, unnecessary CT scans can be harmful in the long run. In addition to the increase in patients requesting CT scans, physicians are more likely to order CT scans than previously. Even when a CT scan doesn't seem necessary, doctors may order the test because they are worried about missing a diagnosis or getting sued by a patient.

Before you go running to your health care provider to request a CT scan the next time you have lower back pain, be sure you know the facts about this test.

What is an X-ray? An X-ray or radiograph uses electromagnetic radiation to make images of a part of the body. The electromagnetic radiation is absorbed differently by different body tissues for example bones appear white, fat appears gray, and the lungs appear black. The radiation goes through you on one side and a picture is generated on the other side. The amount of radiation exposure from a regular X-ray is small.

What is a CT scan (also known as a CAT scan)? A CT scan or computerized tomography combines a series of X-rays taken from many different angles to produce cross-sectional views of body parts. During the CT scan, a table moves the patient through the scanner while electromagnetic X-ray sources and corresponding X-ray detectors rotate around the patient.

The resulting images are assembled by a computer program and the results are sometimes compared to a loaf of sliced bread. Each slice of the CT image provides a detailed 3-D image with much more information than a plain x-ray. A special dye (or contrast) can also be injected in the blood vessels to help see special body parts such as blood vessels and the brain.

Why are more people getting CT scans? Each year, nearly 70 million CT scans are performed in the United States compared to 3 million CT scans in 1980. This is largely due to the availability of CT scanners and the short time required for a scan. Some of the newest models use multiple scanners than can scan the entire body in less than 30 seconds.

What are the dangers of getting a CT scan? In general, there is no immediate danger from getting a CT scan. The test is very quick and painless for most people. If your test involves dye or contrast, an IV must be placed and there is a risk of having an allergic reaction to the dye.

The potential long-term effects are more concerning, mostly due to the amount of radiation exposure. Compared to a traditional X-ray of the chest, a CT scan of the chest uses 150-200 times the radiation. Having a few CT scans during your lifetime will likely be harmless; however, repeated CT scans, especially in children, may be more harmful. The biggest risk from large doses of radiation exposure is cancer. Pregnant women who are exposed to radiation may also risk harm to their unborn child.

If your health care provider recommends a CT scan (or any other test), make sure you understand the risks.


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1 comment:

  • henryj posted at 7:54 pm on Thu, May 19, 2011.

    henryj Posts: 1

    I have had asbestosis for about 20 years that I know about, in 1992 I had a lung operation to remove a small nodule that was not cancerous, every year since then I have had a cat scan as part of a yearly follow up exam.
    This year my doctor retired and a new doctor was assigned to me, and he expressed alarm at all the cat scans I have had, and prescribed a chest xray instead.
    My question, is the amount of radiation I have had serious, and is the risk worth the better results that a cat scan provides