Optimization of exposure factor in full-field digital mammography

Objective To investigate and find out the optimization of exposure factors in full-field digital mammngraphy. Methods The images of NA18-220 mammagraphy phantom were taken at FFDM system with automatic exposure control and the exposure factors were recored. The phantom with FFDM system were exposed By varying mAs (24, 28, 32, 36 and 45 mAs)with the same kV of AEC. The phantoms with FFDM system were exposed by varying kVs (22,23,25,27 and 31 kV) with the same mAs of AEC. The exposure factors were recorded. The images on monitor with the best window width and window level were read by four independent radiologists. The image groups of specks, nylon fibers and masses were assessed by the four experienced readers according to the criteria of 1999 Mammography Quality Control Manual for American College of Radiology. Statistical analysis was performed using analysis of variance. Results The scorings of specks,nylon fibers and masses were not statistically significant (P>0.05) at the exposure factors between 29 kV,40 mAs and 29 kV, 32 mAs. But their exposure doses were different.The imaging quality of the phantom was not significantly different (P>0.05) between 40 mAs,29 kV and 40 mAs,27 kV. But their exposure doses were different. Conclusions To ensure the imaging quality, the AEC of primitive set should be detected. Key words: Full-field digital mammography; Imaging quality; Radiation dose