Posteriorly centered partial CT reduces radiation dose to breast, increases overall radiation
THURSDAY, May 5 (HealthDay News) -- In women undergoing chest computed tomography (CT), bismuth breast shields protect the breasts from radiation exposure better than the new technique of posteriorly centered partial CT, according to a study presented at the annual meeting of the American Roentgen Ray Society, held from May 1 to 6 in Chicago.
Rafel Tappouni, M.D., from the Penn State Hershey Medical Center, and colleagues evaluated the potential for reducing radiation to the female breast in chest CT using bismuth shields and posteriorly centered partial CT. Four calibrated thermoluminescent dosimeters (TLDs) were placed anteriorly and posteriorly to an anthropometric torso phantom, which underwent baseline chest CT with tube current modulation (TCM). This was repeated using breast shields and posteriorly centered partial CT. Readings were taken from the three sets of TLDs, and for effective dose and CT dose index (CTDI) for each scan.
The investigators found that the average doses for anterior and posterior TLDs were, respectively, 686 and 602 mrad for TCM, 426 and 606 mrad for breast shield, and 590 and 826 mrad for posteriorly centered partial CT. The average effective mAs and CTDI were 88 mAs and 5.99 mGy for TCM, 87 mAs and 5.93 mGy for breast shield, and 95 mAs and 6.47 mGy for posteriorly centered partial CT.
"Posteriorly centered partial CT reduces dose to the breast by 16 percent on expense of an 8 percent increase in overall radiation dose. Bismuth breast shield reduced dose by 38 percent without an increase in overall radiation dose. Bismuth shield is the preferred technique to reduce radiation to the female breast," the authors write.
Abstract No. 132