A Medipix2-based imaging system for digital mammography with silicon pixel detectors

We present the first tests of a digital imaging system based on a silicon pixel detector bump bonded to an integrated circuit operating in single-photon counting mode. The X-ray sensor is a 300-/spl mu/m-thick silicon, 14/spl times/14 mm/sup 2/ sensitive area, upon which a matrix of 256 /spl times/ 256 (65536) square pixel, 55 /spl mu/m in side, has been built. The readout chip, named MEDIPIX2, has been developed at CERN within the MEDIPIX2 collaboration and it is composed by a matrix of 65536 readout channels exactly with the same geometry of the detector. The spatial resolution properties of the system have been assessed by measuring the square-wave resolution function and the first images of a standard mammographic phantom were acquired using a radiographic tube in the clinical irradiation condition.