Breast Shields Better at Reducing Exposure Than Posteriorly-Centered Partial CT

The use of breast shields is the technique of choice to protect the breasts of women from radiation exposure while undergoing chest CT examinations, according to a new study.

Rafel Tappouni, MD, and colleagues at Penn State Hershey Medical Center compared the radiation dose to the front and back of a breast phantom using a breast shield and using posteriorly-centered partial CT. 
 

“We found that posteriorly centered partial CT does decrease skin entrance radiation dose to the breast by 16 percent, but increases overall radiation dose to the chest by 8 percent,” said Tappouni.  “The bismuth breast shields, on the other hand, reduced skin entrance dose to the breast by 38 percent without an increase in overall radiation dose,” he said.

Tappouni notes that they now use breast shields at his facility for all female patients up to age 90 who undergo chest CT examinations.

The efficacy of breast shields has a long precedent, but this report specifically compares their use to posteriorly-centered partial CT. Also, the issue has become more important since the International Commission of Radiation Protection (ICRP) increased the tissue weighting factor for the breast from 0.05 to 0.1.

To put the risk into perspective, the delivery of 1 rad to a 35 year-old woman can increase her lifetime risk of breast cancer by 13.6 percent; each CT exam delivers at least twice that amount, Tappouni said.

The study is being presented during the American Roentgen Ray Society Annual Meeting on May 4 in Chicago.