Health

Am I exposed to any radiation during an MRI scan?

By Julie Stachowiak, Ph.D., About.com Guide

Updated September 10, 2009

About.com Health's Disease and Condition content is reviewed by the Medical Review Board

Question: Am I exposed to any radiation during an MRI scan?

I have been reading a lot of articles about the dangers of excess radiation from different tests that people have run for screening or diagnostic purposes, especially computed tomography (CT) scans. CT scans emit a higher level of radiation than traditional X-rays, as they are taking many more images in order to produce a 3-D picture. This can translate into radiation doses up to 200 times higher than an x-ray, and experts are worried that this can mean that we will start seeing higher cancer rates in the future, as people get more and more of these scans. So, what about MRIs? Do they use any radiation?

Answer: The short answer is "no."

Luckily, most of us don’t need many CT scans. However, for those of us with multiple sclerosis (MS), MRI scans are a regular occurrence. Most of us probably have one annually, with additional ones ordered if the neurologist suspects a relapse, our symptoms worsen drastically, or if we are participating in a clinical trial of some sort. Most certainly, we had at least one MRI when we were in the process of being diagnosed with MS.

Digging a bit more into the research on MRIs and radiation put my mind at ease (and it should do the same for you, if you are now concerned).

No, we are not exposed to any radiation at all during an MRI scan. “MRI” stands for “magnetic resonance imaging,” and it uses magnetic and radio waves to produce images -- not radiation.

For a simplified description of how MRIs are made: Extremely strong radio waves (10,000 to 30,000 times stronger than the magnetic pull of the earth) are sent through the body. This temporarily moves the nuclei of the (primarily hydrogen) atoms that make up the body’s cells. When they move back, they emit their own radio waves, which are captured by the scanner.

While it is freaky to think about magnetic waves that strong being sent through your body, there is no risk at all to your body’s tissues during an MRI scan. If you have any implanted devices that contain metal, they could malfunction or cause a problem, so it is essential that you inform your technician of the presence of any device, screw, plate or anything else that you have in your body that you were not born with.

The only possible danger from an MRI is a tiny risk of allergic reaction to gadolinium, the contrast material that is usually used in people with MS, which usually is mild. Also, people with kidney dysfunction are at risk for a more serious condition, called nephrogenic systemic fibrosis, caused by gadolinium.
More: Gadolinium Warning for People with Kidney Disease

There it is -- a long answer to the short question about whether we have to worry about radiation exposure during MRIs. I’m sure that, like me, you are all thrilled to learn that you can have as many MRIs as you would like without having to worry a bit -- especially since most of us find them so very, very fun.