1. System for the investigation of a body volume for diagnosing breast cancer, comprising: an X-ray device for generating projections of the body volume from different directions; a data processing unit coupled to said X-ray device and adapted to reconstruct, from said projections, sectional images of the body volume at different depths, wherein each sectional image corresponds to a certain depth of the body volume; and an indication device for interactively indicating a structure of interest in a reference image, the reference image being derived from one selected from the group consisting of (i) said projections, (ii) said sectional images, and (iii) both said projections and said sectional images, wherein the data processing unit is further adapted to estimate a depth of said indicated structure of interest in the body volume with use of said sectional images and to reconstruct additional sectional images of the body volume around the estimated depth for a fine-tuning of the depth estimation.