Dose Reduction in Automatic Optimization Parameter of Full Field Digital Mammography: Breast Phantom Study

Purpose: We evaluated the impact of three automatic optimization of parameters (AOP) modes of digital mammography on the dose and image quality. Methods: Computerized Imaging Reference Systems phantoms were used. A total of 12 phantoms with different thickness and glandularity were imaged. We analyzed the average glandular dose (AGD) and entrance surface exposure (ESE) of 12 phantoms imaged by digital mammography in three modes of AOP; namely standard mode (STD), contrast mode (CNT), and dose mode (DOSE). Moreover, exposure factors including kVp, mAs, and target/filter combination were evaluated. To evaluate the quality of the obtained digital image, two radiologists independently counted the objects of the phantoms. Results: According to the AOP modes, the score of masses and specks was sorted as CNT>STD = DOSE. There was no difference in the score of fiber among the three modes. The score of image preference was sorted as CNT>STD>DOSE. The AGD, ESE, and mAs were sorted as CNT>STD>DOSE. The kVp was sorted as CNT=STD>DOSE. The score of all test objects in the phantom image was on a downtrend with increasing breast thickness. The score of masses was different among the three groups; 20-21%>30%>50% glandularity. The score of specks was sorted as 20-21%=30%>50% glandularity. The score of fibers was sorted as 30% >20-21% = 50% glandularity. The score of image preference was not different among the three glandularity groups. The AGD, ESE, kVp, and mAs were correlated with breast thickness, but not correlated with glandularity. Conclusion: The DOSE mode offers significant improvement (19.1-50%) in dose over the other two modes over a range of breast thickness and breast glandularity with acceptable image quality. Owning knowledge of the three AOP modes may reduce unnecessary radiation exposure by utilizing the proper mode according to its purpose.