Breast cancer currently accounts for 9% of all cancers worldwide, while in the United States 32% of cancer incidence and 18% of cancer deaths are a result of breast carcinoma. Although recent reports in the popular media have called into question the benefits of mammographic screening, the scientific literature is clear: early detection and treatment of breast cancer have yielded a 20% reduction in the mortality rate in the past decade. Despite the success of current screen-film mammography systems, which account for more than 95% of all units worldwide, they do suffer from a number of drawbacks. The long-term objective of this project is to address these drawbacks by developing a digital mammography system built on innovative medical imaging technologies that have been created in South Africa. Specifically, our aim is to develop a system with the following important features: (1) significantly lower radiation exposure for both patients and healthcare workers; (2) outstanding image quality verified by modulation transfer function (MTF) and detective quantum efficiency (DQE); (3) improved patient comfort through the reduction of painful breast compression; (4) greater coverage of breast anatomy, resulting in fewer missed diagnoses; (5) the provision of computer-assisted diagnosis (CAD) based on the digital images; and (6) reduced time spent in the exam room, leading to increased patient throughput. There will be two overlapping phases to the project. In phase 1, a prototype digital mammography system will be designed, built and tested. We will reduce radiation exposure while maintaining image quality by incorporating a patented slot scanning technique that has recently been approved for whole-body trauma applications by the Food and Drug Administration. Solid-state image sensors will be incorporated in the design of the X-ray detectors, maximizing the signal-to-noise ratio. A careful study of MTF and DQE will be conducted, in addition to manikin phantom studies to measure dose and detection of small lesions. By scanning in a motion that accounts for breast anatomy, it will be possible to improve patient comfort by reducing the need for breast compression and also covering a greater volume of breast tissue. Because the images will be in digital form, this will facilitate CAD applications while also reducing patient examination time. During the last 6 months of the project in phase 2, we will conduct a limited clinical trial of 20 patients, focusing on comfort, breast coverage and diagnostic equivalence.