CCD MOSAIC TECHNIQUE FOR LARGE-FIELD DIGITAL MAMMOGRAPHY

We present a novel technique for large-field digital mammography. The instrument uses a mosaic of electronic digital imaging [charge coupled device (CCD)] arrays, novel area scanning, and a radiation exposure a nd scatter reducing mechanism, The imaging arrays are mounted on a car rier platform in a checker-board pattern mosaic. To fill in the gaps b etween array-active areas the platform is repositioned three times and four X-ray exposures are made, The multiple image areas are then reco mbined by a digital computer to produce a composite image of the entir e region, To reduce X-ray scatter and exposure, a lead aperture plate is interposed between X-ray source and patient, The aperture plate has a mosaic of square holes in alignment with the imaging array pattern and the plate is repositioned in synchronism with the carrier platform , We discuss proof-of-concept testing demonstrating technical feasibil ity of our approach, The instrument should be suitable for incorporati on into standard mammography units, Unique features of the new techniq ue are: large field coverage (18 x 24 cm); high spatial resolution (14 -17 lp/mm); scatter rejection; and excellent contrast characteristics and lesion detectability under clinical conditions.