Recently I had a patient who had been involved in a car accident ask if the x-rays that we were taking of her neck were safe. I wanted to give a brief summary on what the current FDA statements on x-ray safety are and give you a couple resources where you can read more.The FDA estimates that the radiation from a chest ray is roughly equivalent to the background radiation you are exposed to in 10 days on this planet Earth.
The first consideration is that there is no difference between a chiropractic x-ray and any other type of x-ray. While some x-ray machines do vary by brand, what really matters is the part of your body being x-rayed. Different body tissues absorb radiation in different ways.
To give the public a way of monitoring their radiation exposure across many different sources, the FDA uses whats called an effective dosage scale. Each kind of x-ray has an effective dosage associated with it measured in millisieverts (mSv). Since millisieverts isn't a unit of measure most people are familiar with (like a mile or a teaspoon), having a reference value helps put the numbers in context. The FDA estimates that the average person is exposed to 3.0 millisieverts of radiation per year from naturally occurring radioactive materials and cosmic rays. That's what allows them to state that a 0.1 millisievert dosage from a chest x-ray is equivalent to about 10 days of background radiation exposure.
Compared to a chest x-ray, x-rays of the extremities (arms and legs) have a much lower effective dosage and x-rays of the lower torso have a higher effective dosage. Recall that the effective dosage comes mainly from the body part being imaged not the intensity or duration of the x-ray machine pulse. Here's a summary of effective dosages and background radiation equivalents for the various types of x-rays a chiropractor is likely to recommend:
• Extremities - 0.001 mSv – similar to 3 hours background radiation
• Chest - 0.1 mSv - similar to 10 days background radiation
• Spine - 1.5 mSv - similar to 6 months background radiation
The FDA states on its own website "Don't refuse an X-ray. The risk of not having a needed X-ray is greater than the small risk of radiation."
The FDA website and the excellent radiologyinfo.org website from the American College of Radiology and the Radiological Society of North America both point out that disease risks from radiation exposure are cumulative across time and that patients play a critical role in tracking their own exposure levels. Since you may be working with multiple health care providers in different specialty areas, you should keep a log of your exposures. Here is a link to a site where you can download a personal Patient Medical Imaging Record: http://imagewisely.org/Patients.aspx
Note that this article refers to effective exposures and recommendations for adults. If you are pregnant or looking for x-ray safety information for children, visit imagegently.org
Consumer Updates Reducing Radiation from Medical X rays. (n.d.). Retrieved 8 29, 2011, from FDA.gov: http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm095505.htm
Patient Safety X ray and CT. (n.d.). Retrieved 8 29, 2011, from Radiologyinfo.org: http://www.radiologyinfo.org/en/safety/index.cfm?pg=sfty_xray
Radiology Risks Benefits for Patients Image Wisely Image Wisely. (n.d.). Retrieved 8 29, 2011, from ImageWisely.org: http://imagewisely.org/Patients.aspx
Dr. Michael Weir is the clinic director at Bellevue Whiplash Center at Back in Action Chiropractic. We will also be hosting a variety of relevant guest bloggers to help you understand your injuries better.