Performance of mammography grid

The deleterious effect of the scattered radiation in mammographic images has been much studied in the last two decades and it has been demonstrated that contrast can be improved by a factor of 1.4 - 2.5 when scatter is controlled [I]. The grid is the most efficient method for scatter control. Grid performance can be measured by two factors: the Contrast Improvement Factor (CIF) thar quantifies the improvement in the contrast and the Bucky Factor (BF) which describes the exposure penalty imposed to achieve the contrast improvement. The purpose of this work is to measure the CIF and BF employing a grid in mammography for different tube potentials and phantom thicknesses. From these measurements we conclude: Both CIF and BF increase with the phantom thickness; BF decreases with increasing kVp; For 8 cm phantom thickness the CIF increases with increasing kVp, while for 2 and 4 cm thicknesses the CIF changes little with increasing kVp.