Because they use X-rays, mammograms expose you to a low dose of ionizing radiation, which may slightly increase your risk of developing cancer.

While mammograms expose your breast tissue to a small amount of radiation, doctors and researchers widely agree that the benefits outweigh the risks. As the American Cancer Society puts it, “The risk of having a cancer that goes undetected and untreated is greater than the risk of radiation.”

In this article, we’ll cover details about the radiation used in mammograms, how doctors weigh the benefits and risks, and what to ask your doctor if you’re concerned.

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How Much Radiation Do Mammograms Expose You To?

Ionizing radiation is naturally found in the environment. We’re all exposed to a very small amount of background radiation each day. Being exposed to this type of radiation can raise the risk of developing cancer in the future.

Today’s mammograms use less radiation than mammograms used in the past. A standard mammogram exposes you to about the same amount of radiation you would naturally encounter over 34 days.

Mammograms use much less radiation than radiation therapy for cancer treatment.

Radiation From 2D and 3D Mammograms

There are different types of mammograms. A standard 2D mammogram takes pictures of the breast from two angles — top to bottom and side to side. It can be used for screening mammograms and uses a very small amount of radiation.

A 3D mammogram, or tomosynthesis, is a newer test that provides more detailed images of the breast. It can be used as part of a diagnostic mammogram if you’re called back after a screening mammogram. During a 3D mammogram, your breast is compressed, and a machine moves over it in an arc to take X-ray images from several angles.

A 3D screening mammogram exposes you to about the same amount of radiation you would naturally encounter over 42 days. The exact radiation dose can vary depending on the equipment and imaging technique used.

Why Do the Benefits Outweigh the Risks?

The potential benefit of early detection greatly outweighs the risks for most people.

The risk of cancer going undiagnosed or untreated is greater than the risk from radiation exposure during a mammogram.

Research shows that about 1 in every 8 women in the United States will develop breast cancer at some point in their lives. The risk of developing radiation-related breast cancer from repeated screening mammograms is about 1 in every 1,000 women over the course of 34 years of screening.

Having regular screening mammograms lowers your risk of dying from breast cancer. A 2021 review found that women who receive regular screening mammograms are at a significantly lower risk of dying from breast cancer than those who receive mammograms sporadically.

Mammograms are a powerful tool to detect breast cancer early. Research shows that a mammogram can find cancer up to three years before a lump can be felt. Finding and treating breast cancer early can lead to better outcomes.

Mammograms help doctors track changes in the breast. They’re also used during breast cancer treatment to track the tumor size and location. While the radiation from mammograms may slightly increase your risk of developing cancer, the increased risk is very small. This is especially true for women aged 50 and older.

Mammogram Screening Guidelines

The U.S. Preventive Services Task Force recommends that women ages 40 to 74 have a screening mammogram every two years. Other organizations may recommend different screening schedules, so talk with your doctor about when and how often to have a mammogram based on your age and individual risk.

A 2023 review found that continuing to screen older women with mammograms may lead to overdiagnosis. For women ages 75 and older, the USPSTF says there isn’t enough evidence to determine whether the benefits of screening outweigh the harms. Talk with your doctor about whether continued screening is right for you.

What To Ask Your Doctor if You’re Concerned

Talk with your doctor if you’re concerned about radiation exposure. It’s important to understand your individual risks and potential benefits. Consider asking the following questions:

• Why is this test needed?
• Is it safe to have it less often?
• Are other areas of my body going to be exposed to radiation?
• Are there any alternative screening tests you’d feel comfortable recommending instead?

You may have heard about thermography, an imaging test that shows patterns of heat on or near the surface of the breast without using radiation. At this time, doctors don’t recommend thermography instead of mammograms. It hasn’t been proven to be an effective stand-alone breast cancer screening tool.

Ultrasound and MRI are two tests sometimes used to diagnose breast cancer that don’t expose you to radiation. Ultrasound works with sound waves, and MRI works with magnetic fields and radio waves.

If you receive healthcare from different hospitals or facilities, consider tracking your imaging history to prevent unnecessary or repeat tests.