How good is better? A comparison between the Medipix1 and the Medipix2 chip using mammographic phantoms

Two mammographic phantoms have been used to compare the imaging capability and quality of the two existing generations of the Medipix detector. dipix chips are photon counting X-ray pixel detectors which were developed within the framework of the Medipix Collaboration.11http://www.cern.ch/MEDIPIX or this comparison relevant—changes realized in the second chip generation (Medipix2) are the reduced pixel size (55 μm×55 μm instead of 170 μm×170 μm for the Medipix1) and the larger number of pixels (256×256 instead of 64×64), resulting in a larger active area and a higher spatial resolution. ging selected parts of the phantoms using both detectors under the same conditions it is possible to make a direct comparison between the imaging properties of both chips. Main aspects of the experiments were the resolution of high-contrast details and low-contrast imaging. Since these measurements have been made without an anti-scatter grid, additional simulations have been performed to estimate the influence of scattered photons on the image quality. Also a simple measurement regarding the modulation transfer function (MTF) is presented for both detector generations.