Planmed (Finland)

This paper presents the optimized target --- filter combinations to meet with the high image quality and the lowest possible average glandular dose in digital mammography based on amorphous selenium (a-Se) detector technology. Study also provides recommendations for target-filter combinations in digital mammography for different breast thicknesses. The full field digital mammography (FFDM) system based on a-Se technology, which is also a platform of tomosynthesis prototype, was used in this study. X-ray target --- filter combinations, which we studied, were tungsten (W) --- rhodium (Rh), W --- silver (Ag), W--- molybdenum (Mo), and W --- tin (Sn). The average glandular doses (AGD) were calculated using a specific program, which automates the method described by Dance et al. Image quality was evaluated technically; contrast and noise analysis. By using W---Rh, W---Ag, W---Sn, W---Mo target-filter combinations it is possible to achieve a significantly lower average glandular dose compared to Mo---Mo or Mo---Rh. The average glandular dose reduction was achieved from 40 % to 60 % depending, which were the selected target-filter combination and the breast thickness. In the future, the evaluation will concentrate to study the effect of higher kV (> 35 kV) values, which might be useful when optimizing the dose in digital mammography.