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Mammography has served the population of women who are at-risk for breast cancer well over the past 30 years. While mammography has undergone a number of changes as digital detector technology has advanced, other modalities such as computed tomography have experienced technological sophistication over this same time frame as well. The advent of large field of view flat panel detector systems enable the development of breast CT and several other niche CT applications, which rely on cone beam geometry. The breast, it turns out, is well suited to cone beam CT imaging because the lack of bones reduces artifacts, and the natural tapering of the breast anteriorly reduces the x-ray path lengths through the breast at large cone angle, reducing cone beam artifacts as well. We are in the process of designing a third prototype system which will enable the use of breast CT for image guided interventional procedures. This system will have several copies fabricated so that several breast CT scanners can be used in a multi-institutional clinical trial to better understand the role that this technology can bring to breast imaging.

Over the past several years, digital mammography systems have been installed clinically across North America in small but growing numbers. A photostimulable phosphor-based full-field digital mammography image was evaluated in this investigation. Commonly known as computed radiography (CR), its use closely mimics the screen-film mammography paradigm. System performance using modulation transfer function (MTF) and detective quantum efficiency (DQE) metrics show MTF(2.5 mm(-1)) = 0.5, DQE(2.5 mm(-1)) = 0.3, and MTF(5.0 mm(-1)) = 0.2, DQE(5.0 mm(-1)) = 0.05, for a 26 kVp beam, 0.03 mm molybdenum tube filtration, 4.5 cm tissue attenuation, and 15 mR incident exposure to the detector. Slightly higher DQE values were measured at 32 kVp with 0.025 mm rhodium tube filtration. CR mammography advantages include the ability to use existing mammography machines, where multiple rooms can be converted to "digital" operation, which allows overall cost savings compared to integrated digital mammography systems. Chief disadvantages include the labor-intensive handling of the cassettes prior to and after the imaging exam, lack of a direct interface to the x-ray system for recording technique parameters, and relatively slow processing time. Clinical experience in an IRB-approved research trial has suggested that digital mammography with photostimulable storage phosphors and a dedicated CR reader is a viable alternative to conventional screen-film mammography.