Monday, October 4, 2010

X-rays linked to increased childhood leukemia risk

Diagnostic X-rays may increase the risk of developing childhood leukemia, according to a new study by researchers at the University of California, Berkeley's School of Public Health.

Specifically, the researchers found that children with acute lymphoid leukemia (ALL) had almost twice the chance of having been exposed to three or more X-rays compared with children who did not have leukemia. For B-cell ALL, even one X-ray was enough to moderately increase the risk. The results differed slightly by the region of the body imaged, with a modest increase associated with chest X-rays.

The new findings, published in the October 2010 issue of the International Journal of Epidemiology, come from the Northern California Childhood Leukemia Study, a population-based case-control study that includes 35 counties in the northern and central regions of the state. ...

"X-rays are a valuable tool, and our findings indicate that their use should continue to be judicious," said Karen Bartley, doctoral student in epidemiology and first author of the study. "Of greater concern, perhaps, is the use of newer imaging technologies, which are becoming more common and which produce far higher doses of radiation."

Computed tomography (CT) scans, for instance, produce a 3-D image by compiling together multiple "slices" of 2-D images that were taken as the scanner moved along. A 2009 study from the National Cancer Institute projected that the 72 million CT scans received by Americans in 2007 would lead to 29,000 excess cancers. The number of scans in the United States has increased over recent decades, going from 3 million scans in 1980 to more than 70 million a year today.

"The findings about increased leukemia risk certainly warrant further investigation," said UC San Francisco radiologist Dr. Rebecca Smith-Bindman, who was not part of the X-ray study. "If even plain film X-rays are associated with an increased risk of leukemia, then one has to wonder about CT scans, some of which can generate 500 times the dose of radiation of an X-ray." ...

via X-rays linked to increased childhood leukemia risk.

One dentist I consulted required a Cone Beam CT scan before he would do any orthodontic work.  No thanks, I'll take the imperfect teeth.
The risk of cancer associated with popular CT scans appears to be greater than previously believed, according to two new studies published Monday in the Archives of Internal Medicine. The findings support caution against the overuse of CT scans and other medical technologies that use radiation. - wsj

To be fair, this particular type of CT scan does involve less radiation exposure according to one University of Washington web page. According to NOAA you would normally get between 0.0374 µSv to 0.0412  µSv per hour,  so getting slammed with 30 to 100 µSv in a few seconds is an incredible surge of energy.

That energy can break a lot of DNA in your head. Most damage to your cells will be repaired, or will be harmless, but getting x-rays is like playing the cancer lottery.

Type of exposure

Radiation Dose

Conventional CT

Maxilla – 250µSv
Mandible – 480µSv

Cone Beam CT

Double jaw – 30-100µSv

Actually, you have a better chance of winning the cancer lottery than the real lottery.  Well, let's see. The chances of winning the 6-from-49 lotto are 1 in about 14 million. (13,983,816). How does that compare to the odds of getting cancer from an X-ray?
X-rays cause 700 cases of cancer every year in the UK, around 5700 in the USA, and a total of 18,500 cases overall in 15 developed countries, a new study has found. - lancet, Volume 363, Issue 9406, P345, 31 January 2004

Looked at another way: Ten dental X-rays 'raise cancer risk by five times'
Dental X-rays given to millions of Britons every year may dramatically increase the risk of thyroid cancer, scientists warned last night. Researchers found that patients who had been X-rayed by their dentist at least ten times were up to five and a half times more likely to develop the disease. They have now warned that X-rays should not be given at check-ups or when registering new patients  -  despite these practices being common in many dental surgeries.  (DailyMail - unverified, from OnLineNigeria)

I've had way too many x-rays. I recall about 8 chest-X rays, tons of dental x-rays, including two different panoramic x-rays of my jaw.

Luckily, you can fight cancer by eating the right foods.

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