With the current increase of direct full field digital mammography (FFDM) and computerized radiography (CR) equipment at the radiological facilities, researches have been developed with purposes for checking the results from CAD schemes applied to the digital mammographic images obtained from such equipments. Here tests were performed by imaging an anthropomorphic breast phantom – Model 18-226, Victoreen, Inc. – besides using actual mammograms obtained in four different mammography systems as well. The phantom images were acquired from a FFDM system, two other CR systems and a conventional analogical unit. The conventional mammograms were digitized by a laser digitizer, model LUMISCAN (Lumisys, Inc., now Eastman Kodak, Inc.), with 12 bits of contrast resolution. Intensity features were extracted from some regions of interest (ROIs) selected from the digital mammograms in order to investigate the intensity variation along the phantom images. The analysis allowed to determine a standardization in order to provide a better evaluation of the effect of different mammographic imaging technologies as considered in this work. The intensity variation is closely related to the contrast, since it is related to the optical density sensitivity during the image acquisition process. Therefore, the average of features values was used in order to provide a more objective analysis, since the contrast changes according to the equipment operational parameters during the image acquisition. The results have indicated a much smaller variation for the sets from the CR systems and the FFDM one, revealing low contrast images. The tests performed here with the phantom images are in agreement with those obtained with actual breast images, which also have pointed out larger intensity variation for the digitized mammograms than for the direct digital ones.