How Much Radiation Exposure Do You Get From CT Scans?

August 22, 2010

Dear EarthTalk: Should I fear radiation exposure associated with medical scans such as CT scans, mammograms and the like?

The short answer is – maybe. Critics of the health care industry postulate that our society’s quickness to test for disease may in fact be causing more of it, especially in the case of medical scans. To wit, the radiation dose from a typical CT scan is 600 times more powerful than the average chest x-ray.

A 2007 study by Dr. Amy Berrington de Gonzalez of the National Cancer Institute projected that the 72 million CT scans conducted yearly in the U.S. (not including scans conducted after a cancer diagnosis or performed at the end of life) will likely cause some 29,000 cancers resulting in 15,000 deaths two to three decades later. Scans of the abdomen, pelvis, chest and head were deemed most likely to cause cancer, and patients aged 35 to 54 were more likely to develop cancer as a result of CT scans than other age group.

Another study found that, among Americans who received CT scans, upwards of 20 percent had a false positive after one scan and 33 percent after two, meaning that such patients were getting huge doses of radiation without cause. And about seven percent of those patients underwent unnecessary invasive medical procedures following their misleading scans. CT scans are much more common today than in earlier decades, exacerbating the potential damage from false positives and excessive radiation exposure.

“Physicians and their patients cannot be complacent about the hazards of radiation or we risk creating a public-health time bomb,”says Dr. Rita Redberg, a cardiologist at University of California-San Francisco. “To avoid unnecessarily increasing cancer incidence in future years, every clinician must carefully assess the expected benefits of each CT scan and fully inform his or her patients of the known risks of radiation.”

CT scans are not the only concern. Mammograms are now routine for women over 40 years old. But some studies suggest that these types of screenings may cause more cancers than they prevent. Because of this, the federally funded U.S. Preventive Services Task Force now recommends that women not otherwise considered high risk for breast cancer wait until age 50 to begin getting mammograms -and then to get them every two years instead of annually. However, the American Cancer Society argues that such restraint would result in women dying unnecessarily from delaying screenings.

Women with a family history of breast cancer may be at greatest risk. Researchers from the University Medical Center Groningen in the Netherlands found that five or more x-rays – or any exposure to radiation – before the age of 20 for “high risk”women increased the likelihood of developing breast cancer later by a factor of two and a half.

Individuals should ask tough questions of their physicians to determine if and how much screening is absolutely necessary to look for suspected abnormalities. Our knowledge of the risks of radiation-based screenings will only help us to make more informed decisions about our health.

CONTACTS: National Cancer Institute, www.cancer.gov; American Cancer Society, www.cancer.org; University Medical Center Groningen, www.umcg.nl.

SEND YOUR ENVIRONMENTAL QUESTIONS TO: EarthTalk, c/o E The Environmental Magazine, P.O. Box 5098, Westport, CT 06881; earthtalk@emagazine.com. E is a nonprofit publication. Subscribe: www.emagazine.com/subscribe; Request a Free Trial Issue: www.emagazine.com/trial.

Filed in: Responsible • Tags: , ,

About the Author:

After a varied past of being a test driver for automotive television programs, a Hollywood studio lackey, and an online media sales director, David is now the publisher and editor of The Good Human. In his spare time he rides motorcycles, drinks good beer, and builds stuff in the garage. You can follow him on Twitter at @thegoodhuman or G+ at Google
Like this post? If so, please consider subscribing to my full feed RSS. Or, if you would prefer, you can subscribe by Email:

Enter your email address in the box below. Address will only be used to deliver a daily email and you can unsubscribe at any time.

Comments (2)

  1. Marie says:

    This is a big issue for me. I am a cancer surviver (Hodgkins Lymphoma at age 38). To date I’ve had 6 CT scan sessions of my torso and 5 PET scans, as well as 1 month of solid radation treatments to finish off my 6 months of chemotherapy. Every 6 months my doctors want new scans to see how my chest/neck/pelvis looks to scan all of my lymph nodes, and to make sure the tumors aren’t recurring. And to top it off I’m now “high risk” for breast cancer from my radiation treatments, so I have to have a mamogram every year and I’m only 40. I have to wonder, is all this radiation to make sure my cancer’s not reoccurring causing me cancer?