A method for assisted positioning of an organ is provided. An acquisition system comprises a platform underneath which a detector is placed for the acquisition of radiographic medical images, during which a radiation source is moved over different successive positions with respect to the detector, wherein at least one medical image is acquired at each position of the radiation source. The method comprises illuminating the platform with a light source of the acquisition system to assist the positioning of the organ on the platform; and determining, with a drive unit of the acquisition system, a positioning limit on the platform based on the distance separating the platform and a compression paddle used to compress the organ and based on the position of the light source relative to the detector, wherein the positioning limit on the platform is a limit beyond which the organ must not lie.