ABSTRACT The image quality assessment of a radiographic phantom image is one of the fundamental points in a complete quality control programme of a radiographic equipment. In the radiographic technique it is necessary that objects with low contrast and diameter could be distinguish of its background, to carry out a suitable diagnosis. So, the quality of the obtained image is very useful to characterize the physical properties of the imaging chain. In this thesis a method has been developed to analyse the digital image quality of a mammographic phantom by means of automatic process techniques, obtained by a film-screen and computed radiography mammographic equipments. The use of digital system allows the directly acquisition of the image, avoiding the digitisation that it is necessary for the automatic analysis of the image obtained by a traditional film-screen equipment. The techniques used for the image treatment are standard techniques as the image thresholding to detect objects, the regional growing for pixels pooling, the morphological operator application to determine the objects shape and size, etc... This study allows the obtention of information about the phantom characteristics, that due to its small size and lowly contrast can be obtained very difficultly by direct observation. The final aim of this work is to obtain one or more parameters to characterize the reference phantom quality image in an objective way. These parameters will serve to compare images obtained at different mammographic centers and also, to study the temporal evolution of the image quality produced by determined mammographic equipment.