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By Heather Cugini, MD

If you were offered a breast cancer screening test that was painless and radiation-free, it might sound like an easy alternative to a mammogram. But when it comes to detecting breast cancer, “radiation-free” does not necessarily mean “better”—and a breast ultrasound is not a replacement for a screening mammogram. Ultrasound can be an important supplemental tool for some patients, but mammography remains the standard first-line screening test because it can detect certain early signs of breast cancer that ultrasound may miss.

So, do mammograms use radiation? Yes.

Should you be worried? Probably not.

Here is some radiation reasoning.

Breast cancer is one of the oldest known human malignancies, with the earliest written record appearing around 1600 BCE. Today, approximately 42,000 women and around 500 men in the United States die from breast cancer each year. Breast cancer is the second-leading cause of cancer death among U.S. women, and a woman’s lifetime risk of dying from breast cancer is approximately 1 in 43.

Mammograms have been a standard first-line imaging tool for the detection of breast cancer since the 1990s. Since 1989, breast cancer death rates have declined by 44% due to earlier detection and improved treatments.

Do mammograms use radiation?

Yes. Mammograms compress the breast to reduce its thickness and then use X-rays to create pictures of the breast. X-rays use a specific type of radiation called ionizing radiation.

It is well documented that exposure to ionizing radiation can change molecules within the cells of our bodies and that, at sufficient doses, it may cause eventual harm, including cancer. Interestingly, ionizing radiation is also used in much higher and carefully targeted doses to treat cancer.

Ionizing radiation can come from both natural and human-made sources. Natural sources, including the atmosphere, soil, and certain foods, typically expose us to low amounts of radiation every day. Human-made sources include medical imaging, smoke detectors, and equipment used to disinfect medical instruments or sterilize blood products. The amount of radiation emitted varies considerably depending on the source.

How much radiation does a mammogram use?

Mammography uses low-dose X-rays. Radiation exposure is measured using a unit called a millisievert, abbreviated as mSv.

A standard mammogram delivers roughly 0.28 to 0.4 mSv. That is approximately two to four times the radiation exposure from a single chest X-ray and substantially less radiation than most CT scans.

The average person in the United States receives approximately 3 mSv of natural background radiation every year simply by living on Earth. Therefore, the radiation exposure from one mammogram is comparable to approximately seven weeks of the natural background radiation we all receive as we go about our daily lives.

How do we know mammography equipment is operating safely?

Since the 1990s, mammography has been highly regulated by the U.S. Food and Drug Administration through the Mammography Quality Standards Act, commonly called the MQSA.

Mammography facilities in the United States must be MQSA-certified and accredited by an approved federal or state accreditation body. Facilities must undergo periodic reviews of image quality, annual surveys by a medical physicist, and inspections at least annually by a certified MQSA inspector.

The medical physicist verifies that the equipment’s radiation output, beam quality, and exposure controls are operating within established safety and quality standards. These safeguards help ensure that patients receive the lowest radiation dose needed to produce an effective image.

If radiation can be harmful, why do we recommend mammograms?

Mammograms do not prevent breast cancer. What they can do is detect breast cancer earlier—sometimes before a lump can be felt or symptoms develop.

Early detection can improve survival and may also mean less extensive surgery, less need for chemotherapy, and less need for other aggressive treatments. The very small potential risk associated with mammography radiation must be weighed against the well-established benefits of finding breast cancer early.

For most patients who are due for screening, that balance strongly favors having the mammogram.

Why can’t everyone just have an ultrasound or MRI instead?

Compared with mammograms, ultrasounds are radiation-free, less uncomfortable, and often less expensive. Ultrasound is an excellent tool for evaluating a specific breast lump, examining an area identified on a mammogram, distinguishing a fluid-filled cyst from a solid mass, or providing supplemental imaging for some women with dense breast tissue.

However, ultrasound should not be promoted as a replacement for routine screening mammography.

Mammography is particularly effective at detecting microcalcifications—tiny calcium deposits that can be among the earliest signs of breast cancer. These findings may not be visible on ultrasound. A screening mammogram also provides a systematic look at the entire breast, while ultrasound is often used to examine specific areas more closely or to supplement mammography when medically appropriate.

Breast MRI is another valuable imaging tool, but it is generally not recommended as a replacement for mammography in women at average risk. MRIs take longer, cost more, and are so sensitive that they may detect harmless changes. These false-positive findings can lead to additional testing and sometimes unnecessary biopsies.

For women with a significantly elevated genetic or family-history risk, MRI may be recommended in addition to mammography. Supplemental ultrasound or MRI may also be considered for certain women with dense breasts. The right combination of tests depends on a woman’s breast density, personal risk factors, family history, prior imaging, and clinical findings.

The bottom line

The providers at Virginia Beach Obstetrics & Gynecology recommend mammograms because we believe they save lives.

We understand why the word “radiation” can sound frightening. We also understand why a radiation-free screening option may sound appealing. However, ultrasound, mammography, and MRI do not provide the same information and should not be treated as interchangeable tests.

Ultrasound can be extremely useful, but it is usually a supplement to mammography—not a substitute for it.

We are honored to be chosen as part of your healthcare journey, and we would like to help keep you on it. Medical knowledge and screening recommendations continue to evolve, so we encourage you to discuss your individual breast cancer risk, breast density, screening schedule, and imaging options with your healthcare provider.

A few facts to put the radiation dose into perspective

  • Commercial airline passengers are exposed to small amounts of cosmic radiation at higher altitudes. The radiation in one mammogram is equivalent to about 7 weeks of natural background environmental radiation or a single round-trip flight from New York to Los Angeles.
  • Bananas naturally contain potassium, a tiny fraction of which is radioactive. Using the lighthearted “banana-equivalent dose” comparison, the radiation exposure from a mammogram would be roughly equivalent to 700 bananas.

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