Answer to Question #13194 Submitted to "Ask the Experts"

Category: Medical and Dental Patient Issues — Diagnostic X Ray and CT

The following question was answered by an expert in the appropriate field:

Q

I am concerned about my medical radiation exposure. I have had numerous chest and back x rays, a few scans for umbilical hernia and gallbladder issues, as well as a nuclear stress test. These all occurred in about the last 20 years. Last year I had a liver scan due to liver hemangiomas that were found. This year I had a mammogram to monitor a lump, and an abdominal and pelvic scan to rule out appendicitis. I estimate my total radiation dose from these procedures is close to 100 mSv. I have an additional mammogram scheduled next year to continue to monitor the lump. I am supposed to travel by plane later this year for work. I feel I should cancel my trip and my mammogram due to both adding to my radiation exposure. What should I do?

A

I understand there is a lot of scary information available about radiation, but I want to reassure you that the risk from your medical exposures and travel is very low. While your cumulative medical radiation dose may be close to 100 mSv, it has been over a long period of time. Our bodies have mechanisms to repair damage caused by radiation.

The additional risk from each future exposure to small amounts of radiation, such as from a mammogram or a flight, are very low or non-existent. We are all exposed to natural background radiation on a regular basis. In fact, the average background radiation dose in Colorado is approximately twice the national average but the cancer incidence in Colorado is below the national average. It is also reassuring to know that as we age, each radiation exposure carries a lower cancer risk than when we were younger. There are a lot of causes for cancer and we can't tell what caused any particular cancer. All we can do is calculate the probabilities.

While we want to ensure that all medical uses of radiation are justified and optimized, it is important to realize that there are risks associated with not having medical imaging. The estimated average effective dose from bilateral mammography is 0.48 mSv. Cancelling your mammogram next year could cause a delay in diagnosing cancerous changes in the lump that is being monitored or a new suspicious lump. I recommend discussing your concerns with your doctor so you know the risks and benefits of any given imaging and can make an informed decision.

The estimated dose from a flight from the east coast to the west coast of the United States is only approximately 0.035 mSv. The backscatter x-ray scanners used in some airports result in radiation doses much smaller than the flight, and the millimeter-wave scanners don't use ionizing radiation. I understand the risks of radiation and don't let the radiation dose from flying keep me from travelling, even half-way around the world.

While medical imaging using x rays and flying do expose you to radiation, the associated risks are very, very low compared to many other things we do on a daily basis. I hope this will help to alleviate your worries so you can make informed decisions and not let fear keep you from living the life you want to live

Deirdre H. Elder, MS, CHP, CMLSO

Ask the Experts is posting answers using only SI (the International System of Units) in accordance with international practice. To convert these to traditional units we have prepared a conversion table. You can also view a diagram to help put the radiation information presented in this question and answer in perspective. Explanations of radiation terms can be found here.
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