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Radiation, How Much Is Too Much

Ever think about all of the things you do that expose you to radiation?   With cancer rates rising each year, now is a good time to start paying attention to radiation.

If you live at a high altitude (in the mountains) you are exposed to more radiation than at lower elevations.  Radiation also comes from minerals in the ground, Radon gas in your home, flying on a plane, sunlight, and more.  What about the different medical tests and procedures you undergo?  Did you ever wonder just how much radiation you are subject to throughout a year?  A lifetime?

According to the National Council on Radiation Protection and Measurements (NCRP), the average annual radiation dose per person in the United States (U.S.) is 6.2 millisieverts (mSv) or 620 millirem (rem).1  The sievert is the international unit and the rem is the U.S. unit.

As an example, a Computed tomography (CT) scan of the cervical spine has an average dose of radiation of 6 mSv, a mammogram on average is .4 mSv and a CT angiogram (heart catheterization) is on average 16 mSv. 2  So how much is too much? 

Research shows there starts to be a risk for cancer at about 100 mSv per year.  A dose of 10,000 mSv would be fatal, about 5,000 mSv would be lethal in about 50% of those exposed (LD50) at a certain point in time (and 100% lethal over a longer period of time that is impossible to predict).

While the above statistics discuss risk as a yearly (annual) dose of radiation, there is a risk of cancer based on the cumulative dose of radiation over a lifetime, which needs to be considered as well. With this in mind, we should be conscientious of the various imaging studies that are routinely performed on us. Diagnostic studies are usually of more importance than preventative screenings, so we each can start with weighing our individual risk versus benefit of the various screening tests that deliver a small dose of radiation each time they are performed. Examples of screening tests that may be recommended but are not necessarily essential are dental X-rays, DEXA bone scans for osteoporosis screening, and low dose Chest CT scans for lung cancer screening.

The most difficult part of this equation is not knowing what our unique risks may be. So it is challenging to strike a balance between being too relaxed on one hand, and hypervigilant on the other, with regard to radiation exposure. I personally recommend taking an inventory of your personal lifelong exposures, then work with your primary care doctor or do your own research online about the doses of each of these exposures as a cumulative dose of radiation.

Exposures can be broken down by medical and dental imaging test, air travel, sun exposure, time spent in high altitude, environmental exposures like Radon gas or potentially occupational exposures, etc. This all has to be balanced against our estimated risk based on family history and behaviors such as smoking, alcohol use, exercise, diet, body habitus, and more, all of which can increase risk for various types of cancer.

This blog is intended to get you thinking about this subject, for yourself and your children. There are no hard and fast answers because we are all so uniquely different. This should serve as a starting point on your journey with regard to lifetime radiation exposure. The good news is that the X-ray and CT machines used in medical facilities have become far more efficient in recent years, thus rendering a significantly lower dose of radiation for the same high quality image. Likewise, air travel has become faster, rendering shorter flight times and less atmospheric radiation exposure. Ultrasound and MRI technology has been able to replace X-rays and CT technology for a large variety of screening and diagnostic tests.

We have made significant progress at reducing our exposure to radiation in recent years, but we still have a ways to go. Anything we can do to mitigate this risk is worthwhile to consider.

Justin Groode MD | Patient Advocate Alliance LLC

Thanks to Healthcare Fraud Shield for a portion of the content of this post.