The long-term objective of this research is to provide the mammography clinician with equipments and methods to find breast cancer at an earlier stage. To achieve this objective, a National Digital Development Group (NDMDG) has been defined by the National Cancer Institute (NCI). Five research components hake been listed: * Software and hardware for digital mammography * Image processing * Computer aided diagnostic/CAD * Preclinical and Clinical evaluations * Telemammography This proposal concerns the first component of this list "Software and Hardware for Digital Mammography."" The task will be to build a high- performance digital image detector and to deliver it, integrated in a functional system, to Massachusetts General Hospital for mammography screening. The specific aims of the GE Mammography System Development Program will be to--- * Design prototype digital image detector with a 18 cm x 23 cm active area. * Integrate it into a system with a processing computer, a high resolution display, and hard-copy printer. * Measure its physical performances as compared to film/screen. * Deliver the system to Massachusetts General Hospital for clinical tests and data acquisition. * Assure complete functionality and maintenance of the system after installation. This equipment will assure mass screening of asymptotic women. Hence it will operate at low dose high definition and feature fast recording, processing and display. For image processing and in order to avoid retakes, a large latitude and a digital output will be provided. A simple adaptation to a screen film system will be also one of the goals.