How dangerous is radiation from a mammogram?

April 18, 2018 | by Christine Gresik, MD

Somewhere along the line, you may have been told that radiation exposure from a mammogram can cause breast cancer. If you’ve always avoided a mammogram because of this fear, it’s time to get the facts — it could save your life. 

Here’s how a mammogram works: 

Mammograms are designed to look only at breast tissue and require very small doses of radiation—lower doses than usual X-rays. The machine uses two plates that flatten the breast to spread the tissue apart, giving radiologists a better picture of the breast. 

A new breast imaging tool, 3D mammography, takes low-dose X-rays from a variety of angles to create a 3D picture of the breast. This helps radiologists characterize individual breast structures without the confusion of overlapping tissue, which is helpful for women with dense breast tissue.

How much radiation exposure are we talking about? Modern-day mammography involves a tiny amount of radiation exposure, even less than a standard chest X-ray. On average, the total radiation dose for a typical mammogram with two views of each breast is about 0.4 millisieverts, or mSv. (A mSv is a measure of radiation dose). 

To put in perspective, Americans are normally exposed to 3 mSv of radiation each year just from their natural surroundings. The radiation dose used for a screening mammogram of both breasts is about the same amount of radiation a woman would get from her natural surroundings in about seven weeks.

While repeated X-rays can increase the risk of breast cancer over time, the risk is very small. Studies show the benefits of receiving a mammogram outweigh the risks of radiation exposure for most women. In fact, a mammogram is the single most effective method of early breast cancer detection.

Mammograms can save lives by finding breast cancer even before physical symptoms develop. This means that more women being treated for breast cancer are able to keep their breasts. When caught early, localized cancers can be removed without resorting to breast removal.

While a diagnostic mammogram can check for breast cancer when symptoms are already present, a screening mammogram checks for breast cancer in a woman who shows no signs or symptoms of the illness. Different organizations have different recommendations for when to start screening for breast cancer.

According to the American Cancer Society, women facing an average risk for breast cancer — meaning they have no family history of breast cancer or other risk factors — can wait until age 45 to start mammograms, but women at age 40 should have the option to start screening with a mammogram every year.

If you're at a higher risk of breast cancer, you may need to be screened earlier and more often than other women. Some breast cancer risk factors include:

  • Genetic mutations
  • Starting menopause after age 55
  • Not being physically active
  • Being overweight or obese after menopause
  • Having dense breasts
  • Having a family history of breast cancer
  • Previous treatment using radiation therapy (e.g., for treating Hodgkin lymphoma)

We now know that very low doses of radiation don't have much impact on breast cancer risk. But some women also avoid getting a mammogram because they have scanxiety. They worry about the exam causing pain, or fear bad news. Yet, the benefit of potentially catching breast cancer in its earliest stages is usually worth it to many women.

Talk to your doctor about your family history and your concerns. Your doctor can help you decide when you should start screening. If there is any possibility that you’re pregnant, let your doctor know.

Learn more about 3D mammograms at Edward-Elmhurst Health. We offer no-referral mammograms that you can schedule online. Go online, find a time that works for you, and schedule your appointment today. It’s easy.

Related blogs:

Managing breast cancer risk and fears 

Answers to your FAQs about mammograms 

When should I get a mammogram?

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