Imaging performance of a GaAs pixel detector

We have tested the imaging capabilities of a GaAs pixel detector using a te st object developed for quality control purposes in mammography and a dedic ated X-ray imaging system. The response of this detector under the same irr adiation conditions has also been simulated by the EGS4 code and a comparis on with an intensifying screen+film digitized image has been made. Our GaAs detector is able to perform a measurement of low-contrast details, with a minimum contrast lower than typically detected by standard mammographic fil m+screen system, in the same conditions of clinical routine, and this shoul d allow for an earlier diagnosis of the breast tumor masses.