Author/Authors :
Bisogni، نويسنده , , M.G. and Del Guerra، نويسنده , , A. and Lanconelli، نويسنده , , N. and Lauria، نويسنده , , A. and Mettivier، نويسنده , , G. and Montesi، نويسنده , , M.C. and Panetta، نويسنده , , D. and Pani، نويسنده , , R. and Quattrocchi، نويسنده , , M.G. and Randaccio، نويسنده , , P. H. Rosso، نويسنده , , V. M. Russo، نويسنده , , P.، نويسنده ,
Abstract :
We are implementing an X-ray breast Computed Tomography (CT) system on the gantry of a dedicated single photon emission tomography system for breast Tc-99 imaging. For the breast CT system we investigated the relevance of the beam hardening artifact. We studied the use of a single photon counting silicon pixel detector (0.3 mm thick, 256 × 256 pixel, 55 μ m pitch, bump-bonded to the Medipix2 photon counting readout chip) as detector unit in our X-ray CT system. We evaluated the beam hardening “cupping” artifact using homogeneous PMMA slabs and phantoms up to 14 cm in diameter, used as uncompressed breast tissue phantoms, imaged with a tungsten anode tube at 80 kVp with 4.2 mm Al filtration. For beam hardening evaluation we used a bimodal energy model. The CT data show a “cupping” artifact going from 4% (4-cm thick material) to 18% (14-cm thick material). This huge artifacts is influenced by the low detection efficiency and the charge sharing effect of the silicon pixel detector.
