Wearing Bra During Chest CT Increased Effect of Dose Reductions

May 2, 2014
Leah Lawrence

Placement of the female breast by keeping a bra on during chest CT did not negatively influence CT imaging quality.

Results of a recent study demonstrated that placement of the female breast by keeping a bra on during chest CT did not negatively influence image quality, and, in fact, increased the effect of dose reduction of a tube current modulated algorithm.

“We demonstrated that wearing a bra increases the percentage of breast tissue within the region of reduced mAs and, therefore, improves the performance of an angle dependent tube current modulated technique,” said study author Anna Seidenfuss, of the department of radiology at University Erlangen-Nuremberg Erlangen, Germany.

According to the study, published in the American Journal of Roentgenology, radiation dose to the glandular tissue of the breast during chest CT is of particular concern, especially in younger women who are often considered to be at the greatest risk of radiation-induced cancer. Breast tissue is also estimated to be more radiosensitive than previously recognized, making it one of the most radiosensitive organs in the body. Therefore, several strategies, including tube current modulation, have been proposed to reduce dose to radiosensitive organs.

“Angle dependent tube current modulated techniques have been proposed and validated in different phantom experiments, which demonstrated that significant dose reduction can be achieved without sacrificing image quality,” Seidenfuss told Diagnostic Imaging. “While phantom measurements are necessary for direct measurement of glandular tissue exposure, they only represent an idealized anatomy.”

To explore how much breast and glandular tissue are within the range of organ-based tube current modulation, Seidenfuss and colleagues conducted a study that included 578 women undergoing chest CT. Group A included 219 women who underwent imaging wearing a bra. Group B included 369 control women scanned without a bra. All CT examinations were performed using an angle-dependent tube current modulation. The researchers then measured the proportion of breast and glandular tissue located within and outside the region of the tube current.

Patients were scanned wearing several different types of bras. No bra, including those with metal, caused artifacts that influenced the diagnostic accuracy of the images.

Patients in Group A were found to have significantly greater amount of breast tissue (91.3 percent vs. 60.4 percent) and glandular tissue (96 percent vs. 67.1 percent) inside the region of tube current reduction than patients in Group B. Patients in Group A across all of the examined age groups experienced similar improvements, with greater improvement rates seen in the older patient group.

Groups were also subdivided according to cup size. Patients in Group A with an A cup size had the greatest amount of breast tissue (97.5 percent) and glandular tissue (98.15) inside the region of the tube current reduction. However, an increasing improvement between Group A and Group B was seen with increasing cup size. The highest effect of wearing a bra was seen in women with cup size E. Women in Group B with cup size E had only 30 percent of breast tissue and 31.8 percent of glandular tissue within the region compared with 83.3 percent of breast tissue and 90 percent of glandular tissue within the region among woman wearing a bra during examination.