Detectors for digital mammography

Mammography is the most technically demanding radiographic modality, requiring high spatial resolution, excellent low contrast discrimination, and wide dynamic range. The development of dedicated mammography systems [1] in the mid-1960s and the refinements in film-screen technology over its long evolution [2,3] were of critical importance in establishing the benefits of mammography in reducing breast cancer mortality [4–10]. The use of film-screen technology over 30 years ensured excellent spatial resolution under optimal conditions. The high spatial resolution requirement was thought to be essential for imaging small and subtle calcifications as small as 100–200 μm, in particular for visualizing its morphology. In spite of the excellent imaging characteristics of film-screen technology under optimal exposure and film development conditions, intrinsically images are more susceptible to artifacts. Small deviations from optimal exposure and processing conditions can have profound effects on mammographic image quality, such as its ability to provide a balanced image over regions of the breast that vary in radiographic density. The well-documented weaknesses of film-screen technology [11–13] include limited dynamic range, limited tolerance to exposure conditions, complexity and instabilities due to the chemical processing of film, and the lack of ability to digitally communicate, store, and enhance the images.