Image noise sensitivity of dual-energy digital mammography for calcification imaging

Dual-energy digital mammography (DEDM) can suppress the contrast between adipose and glandular tissues and generate dual-energy (DE) calcification signals. DE calcification signals are always influenced by many factors. Image noise is one of these factors. In this paper, the sensitivity of DE calcification signal to image noise was analyzed based on DEDM physical model. Image noise levels of two different commercially available digital mammography systems, GE Senographe Essential system and GE Senographe DS system, were measured. The mean noise was about 1.04% for Senographe Essential system, 1.42% for Senographe DS system at 28kVp/50mAs; and was 0.47% for Senographe Essential system, 0.79% for Senographe DS system at 48kVp/12.5mAs. Evaluations were performed by comparing RMS (Root-Mean-Square) of calcification signal fluctuations in background regions and CNR (Contrast-Noise-Ratio) of calcification signals in clusters when these two digital mammography systems were used. The results showed that image noise had a serious impact on DEDM calcification signals. If GE Senographe Essential system was used, calcification signal fluctuations were 200 similar to 300 mu m, and when calcification size is greater than 300 mu m, the probability of acquiring CNR >= 3 is over 50%. If noise reduction techniques are used, the calcification threshold size of CNR >= 3 can be lower.