Radiation in Medical Testing
Hi, my name is Dr. John Shim, and today I want to talk about the risks of radiation from medical tests. In this modern day of medicine, there is an expectation that your doctor will order some tests during your visit. As an orthopedic surgeon, we commonly used tests such as x-rays, MRIs, and CAT scans, and sometimes we may even need to order a test for a bone scan. But are these tests without any risks? For the past 10 years, there has been a lot of concerns about the potential radiation doses associated with each of these tests. But, to give you perspective, understand that we get exposed to radiation every day from the sun, and from nature. Radiation exposure that may cause biologic effects is measured in units called milli sieverts. For the people who live here in the United States, the average natural radiation exposure a year is 3.7 millisieverts. That's the exposure we get from the Sun, our work and our living space. So, what are the radiation exposures of common medical tests? X-rays of your arm or leg is about .001 mSV, or about 3 hours of the natural exposure we experience everyday. X-rays of your lower back, however, is about 1.5 mSV, or equivalent to about 6 months of natural exposure. CAT scans of your spine are at least 6 mSV, which is the equivalent of 2 years of natural exposure to that one test. Even bone scans are at least 6 mSV as well. Doctors and Radiologists have considered the radiation exposures to these tests to be relatively low risk. Still, We do have concerns that radiation exposures are cumulative and therefore the more tests you get, the more radiation you have experienced, and the higher chance of developing consequences including cancer. In general, a few x-rays carry very little risk compared to normal background radiation. On the other hand multiple CAT scans and bone scans can be of concern and if your physicians recommend a lot of these tests, an informed discussion about the risks and benefits of the testing can reduce some of your fears. As a Doctor, I know these tests are not ordered casually, and the potential benefits of identifying causes of complaints outweigh the small risks. associated with some of the radiation. If you're concerned, it is very reasonable to ask your doctor about these risks. This is Dr. John Shim discussing radiation risks to common medical studies. I hope this information was helpful.
We are always exposed to low levels of radiation, and for the most part it does not adversely affect us. Radiation comes from the ground in the form of radon and from the sun in the form of ultra violet rays. We know to test for radon in our houses and to wear sunscreen but what about getting medical tests that use radiation to diagnose?
Radiation is being used more and more in x-ray, CT and nuclear imaging. It is decreasing the amount of “exploratory surgeries” and making diagnosis faster and more accurate. The radiation you get from these tests is ionizing radiation — high-energy wavelengths or particles that penetrate tissue to reveal the body’s internal organs and structures.
Ionizing radiation can damage DNA, causing mutations that may contribute to cancer years down the road. This is why very often people who were treated with radiation in the past may end up with different cancers in the future.
CT alone accounts for 24% of all radiation exposure in the United States, according to a report issued in March 2009 by the National Council on Radiation Protection and Measurements. Radiation is measured in (mSv). A chest x-ray, for example, delivers 0.1 mSv, while a chest CT delivers 7 mSv (70 times as much).
Though there are new machines coming out constantly that decrease the amount of radiation used, we still need to be more careful about the amount of radiation we allow our bodies to absorb. There are several things you can do as a patient to avoid excess radiation and problems down the road:
- Keep track of the x-rays/ CT’s you have had and discuss the actual need for another with your physician.
- Don’t ask for an x-ray or CT just to “complete your physical”. Yes, it happens!
- See if a test not using radiation such as ultrasound or MRI can be used instead.
- When having a mammogram or dental x-rays, ask for the neck guard. It is often not offered, and some are blaming the increase in thyroid cancer on these tests.
- If you work around x-rays make sure you are covered with a lead gown and that there are no cracks in it. Also have monthly measurements taken of radiation exposure.
If the side effects of testing are less worrisome than the actual problem and can prevent unnecessary surgery, then go for it. Just don’t forget to keep track of your testing and take proper precautions.
- Marshall EL, Rajderkar D, Brown JL, Stepusin EJ, Borrego D, Bolch WE. A scalable database of organ doses for common diagnostic fluoroscopy examinations of children: procedures of current practice at the University of Florida. Phys Med Biol. 2019 Apr 23; PubMed PMID: 31013486