Experimental study of beam hardening artifacts in photon counting breast computed tomography

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• 作者：M.G. Bisogni ; A. Del Guerra ; N. Lanconelli ; A. Lauria ; G. Mettivier ; M.C. Montesi ; D. Panetta ; R. Pani ; M.G. Quattrocchi ; P. R ; accio ; V. Rosso ; P. Russo
• 关键词：Beam hardening artifacts ; Single photon counting detector ; Breast CT
• 刊名：Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
• 出版年：2007
• 出版时间：21 October 2007
• 年：2007
• 卷：581
• 期：1-2
• 页码：94-98
• 全文大小：383 K

文摘

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, 55μm 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.