A high resolution scanned projection radiography system is proposed for digital mammorgraphic applications. By using a wide dynamic range CCD detector some of the current limitations encountered in conventional film-screen mammography can be avoided. One-dimensional fan-beam geometry provides very good scattered x-ray reduction. A time-delay-and-integrate (TDI) mode of CCD imaging with a 2048 x 96 element CCD array provides the opportunity to image without the excessive power loading of x-ray tubes which would be required with a 2048 x 1 array, for example. By utilizing TDI charge integration while the detector is scanned, each projection through stationary anatomy is averaged over 96 exposures, thereby providing a significant signal to quantum mottle improvement of approximately 10:1 as compared to a 2048 x 1 detector at the equivalent tube loading. Developmental tasks to be performed include construction of a TDI CCD x-ray detector in which the light output of an x-ray intensifying screen is coupled by means of a lens to the CCD focal plane, measurement of the x-ray sensitivity, noise characteristics and homogeneity of the x-ray detector construction of a moving sample x-ray imaging system based on the TDI detector, and determination of the optimum x-ray spectrum for digital mammorgraphic imaging tasks in order to evaluate its clinical potential. Additionally, image processing tasks to aid in subtle lesion or microcalcivication detection will be surveyed in order that further work toward an artifical intelligence based expert system for breast imaging may result in continuing development phases.
