The invention relates to a tomosynthesis process in the context of mammography, in which several individual images of a breast are taken at different projection angles and in which of information thus acquired, tomographic images are synthesized with the help of an applicable image processing software. The mutual geometry of the imaging means of the imaging apparatus when taking these individual images is determined according to the invention by arranging in the imaging apparatus a calibration structure (20), which includes balls (21) or other small objects absorbing X-radiation which are such placed that their projections will become imaged on said individual images.
