A Novel Solid State Detector for Mammography
The Medipix2 chip is a photon counting X-ray pixel detector, which was developed by the Medipix Collaboration  at the European Centre for Nuclear Research (CERN). It consists of a 700?m silicon detector layer with 256?256 square pixels of 55?m size (Fig.1) which is bump bonded to an equally dimensioned pixel read-out chip . The chip is suitable for mammographic applications due to increased relative efficiency at the low kV values involved. This initial study investigates the dose reductions achieved over conventional mammographic screen-film techniques and evaluates image quality. METHODS: The chip is used in the first clinical study of mammographic applications, comparing Medipix images of lumpectomies to conventional film images. The detector sits in a magnification table (Fig. 2) above the film housing with simple translation used to build up tiled images. RESULTS: Fig.3 shows film (a,c) and initial chip (b,d) lumpectomy images, there is a hook wire for localisation and several faulty pixel lines. Calcifications and a lesion are clearly seen; the locations are slightly altered due to repositioning of the excised sample.