U.S. Population Radiation Exposure On The Rise

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News Posted: Thu, Mar 5 2009 2:11 PM

The National Council on Radiation Protection & Measurements (NCRP) released a report that states that the average effective radiation dose individuals in the U.S. have received in 2006 has increased about 1.7-times since the early 1980s (from 3.6 mSv to 6.2 mSv)*. Contrary to what many might think, however, this almost doubling in radiation exposure does not come from the increased used of consumer electronics devices or from the increase in the number of devices that utilize radio frequencies, such as mobile phones or Wi-Fi networking; but, in fact comes primarily from the significant increase in the last few decades of medical imaging procedures that use ionizing radiation:

"The increase was due mostly to the higher utilization of computed tomography (CT) and nuclear medicine. These two imaging modalities alone contributed 36 percent of the total radiation exposure and 75 percent of the medical radiation exposure of the U.S. population." -- Dr. Kenneth R. Kase, Senior Vice President of NCRP

In the early 1980's, medically-based exposure to radiation accounted for only about 15-percent of the "ionizing radiation exposure of the population of the United States." Background radiation made up the vast majority of this exposure, at 83-percent. This background radiation is made up of naturally occurring radiation from rocks and soil, from our own bodies, from space, and also from Radon gas seeping into buildings. Radiation exposure from "industrial and research uses and occupational tasks," represented only about 0.3-percent, and consumer products accounted for only about 2-percent.

In 2006, radiation from medical sources accounted for a full 48-percent of the U.S. population's exposure. Background radiation exposure accounted for 50-percent, while "occupational/industrial" dropped to about 0.1-percent, and consumer remained around 2-percent. This does not mean, however, that radiation other than from medically based sources have decreased--these are percentages, not absolute exposure numbers--it simply means that radiation exposure from medical sources has vastly increased and therefore it accounts for a larger chunk of the radiation we are exposed to than in the early 1980s.

From the early 1980s to 2006, the average effective radiation dose per individual in the U.S. from medical sources has jumped about 5.7-times, from 0.53 mSv to 3 mSv. Background radiation has barely moved from 3 mSv in the early 1980s to 3.11 mSv in 2006; as is the same with radiation from "occupational/industrial" sources--which was at 0.010 in the early 1980s, and was at 0.008 in 2006. The NCRP's data shows that consumer-based products accounted from between 0.5 and 0.13 mSv in the early 1980s, as was at 0.13 mSv in 2006--which, depending on how you choose to crunch the numbers can mean anything from a an almost three-fold increase to no significant change at all.

Before people panic and start wearing lead-lined clothes, the American College of Radiology (ACR) wants people to be aware that this additional exposure of radiation from medical sources is actually a direct result of improved health care and its benefits often outweigh the risks:

"Medical imaging has revolutionized medicine and is undoubtedly saving and extending lives everyday. It is vitally important that patients do not put off needed imaging care based on this Report which neither quantifies the associated health risks nor specifies the radiation protection actions that should be taken." -- Sanjay Saini, MD, MBA, SCBT-MR President

"It is essential that this Report not be interpreted solely as an increase in risk to the U.S. population without also carefully considering the tremendous and undeniable benefits of medical imaging. Patients must make these risk/benefit decisions regarding their imaging care based on all the facts available and in consultation with their doctors." -- James H. Thrall, MD, FACR, Chair of the ACR Board of Chancellors

The ACR is concerned, however, that many of the radiation-based medical procedures are often overused and even unnecessary in some cases. One potential cause of this is that studies have shown that "when physicians refer patients to facilities in which they have a financial interest, imaging utilization is significantly increased." So despite the headlines of recent years citing the radiation dangers from our mobile phones and other consumer-electronics devices, it appears that the larger danger might in fact actually come from where our doctors choose to invest their money.

* 1 mSv = 0.1 rem, for a quality factor Q=1 (Source: Wikipedia)

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Jeremy replied on Thu, Mar 5 2009 2:32 PM

CT-C. Computer Tomography - Cardiac. The latest and "greatest" recent advancement in medical imaging, is trying to supplant Nuclear Medicine cardiac imaging as the standard for diagnostic cardiac imaging.

Question is, would you rather have radiation exposure equivalent to 500-600 chest X-rays, or exposure equivalent to 2-3 chest X-rays? Yearly follow-ups are the norm with cardiac imaging, so keep that in mind. All for a marginal increase in sensitivity/specificity on a test that many radiologists are not currently qualified to read.

I find it amusing that patients get a bit freaked by nuclear medicine due to the title, but think nothing of going in for CT, even though the exposure from the NM procedure is typically a fraction of exposure from a CT.

Not that I work in the field or anything . . .

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3vi1 replied on Fri, Mar 6 2009 8:48 AM

I think the studies wrong. I blame the mutant population, and think they should all be rounded up and put into camps to protect us "normal" folks. Glenn Beck said this would happen!

What part of "Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn" don't you understand?


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Jeremy replied on Fri, Mar 6 2009 2:06 PM

My shotgun's ready for when the mutants stage their coup. Course, I'm very worried that Professor Xavier already knows this. Plus, I don't think the gun will help. Crap, I'm screwed.

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Dave_HH replied on Sat, Mar 7 2009 9:44 AM

Heheh... you guys are certifiable. :)

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I think this would explain the increased number of super heroes. (Or at least super hero movies) in the last few years.

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