Does Mammography Radiation Increase Cancer Risks?

Mammography scatter radiation appears to not be dangerous

(RxWiki News) Have you heard that radiation from mammography can cause other cancers? Maybe you’ve heard recommendations that a shield be used to protect the thyroid. A new study took a look at these concerns.

Radiation from mammography that “scatters” to other parts of the body does not increase a person’s risk of developing cancer, according to recently presented research.

"Ask what type of mammography equipment your doctor uses."

A new study measured just how much radiation from mammography other parts of the body were receiving. According to investigators, led by Alison L. Chetlen, DO, assistant professor of radiology at Penn State Hershey Medical Center, radiation exposure was either minimal or very low - less or about the same level of exposure received from natural sources.

When a mammogram is taken, radiation from the primary beam “scatters” in all directions. While it’s not nearly as strong as the imaging beam itself, there has been concern that this residual radiation could be damaging. Of particular concern was radiation reaching the thyroid gland.

Dr. Chetlen and her team captured and measured the amount of radiation a screening digital mammogram delivered to the thyroid and salivary glands, the sternum, uterus and lens of the eye. A total of 207 women were equipped with six meters to measure how much radiation was absorbed.

A milligray is the unit of measure for absorbed radiation. The thyroid and the salivary gland each received 0.05 mGy. This is actually only a fraction of the amount of radiation we’re exposed to from natural sources, according to the researchers.

The uterus and eye received barely measurable amounts of radiation, suggesting that mammograms don’t impact pregnancy or patients who have cataracts. The researchers found that all areas measured – except for the sternum – absorbed less than 2 percent of the radiation a person receives annually from natural sources.

"This study provides reassurance that mammographic screening should not increase risk of developing other cancers in tissues in close proximity to the breast,” Benjamin A. Smith, MD, assistant professor of radiation oncology at The University of Texas MD Anderson Cancer Center.

“Women can be counseled about these study findings and encouraged to receive screening mammographic as recommended. Screening mammography has been shown in clinical trials to lower the risk of breast cancer death," Dr. Smith said.

Concern regarding thyroid radiation exposure comes in the wake of the fact that thyroid cancers have doubled in women between 2000 and 2008.

Authors of the study conclude that not only are thyroid shields not necessary, they may actually increase the amount of radiation exposure.

"A thyroid shield gets in the way of the exam and can actually cause an increase in radiation dose by necessitating repeat exams," Dr. Chetlen said in a press release. As a result, she says thyroid shields are not recommended during mammography.

Findings from this study were presented at 2012 annual meeting of the Radiological Society of North America (RSNA). All research is considered preliminary before it’s published in a peer-reviewed journal.

Review Date: 
November 29, 2012