An X-ray mammography equipment (1) of the dual-energy type is calibrated through a plurality of calibration elements (8) associated with predetermined pairs of iodine concentration in the element and glandularity configuration of the element having different element thicknesses； for each calibration element, a low-energy image value and a high-energy image value are obtained (23)； for each thickness of the calibration elements, the coefficients of an image combination formula are calculated (24) through a regression technique using the previously obtained image values and the iodine concentration values of the calibration elements. The coefficients thus calculated are used (37A, 35B, 35C) by the mammography equipment (1), during the imaging phase, to combine (35A, 36A, 35B, 35C) the low-energy and high-energy images.
