Amendolia, Salvator Roberto and Bisogni, Maria Giuseppina and Bottigli, Ubaldo and Ciocci, Maria Agnese and Delogu, Pasquale and Dipasquale, Giovanna and Fantacci, Maria Evelina and Faucci Giannelli, Michele and Maestro, Paolo and Marzulli, Vincenzo M. and Pernigotti, Elena and Rosso, Valeria and Stefanini, Arnaldo and Stumbo, Simone (2000) Low contrast imaging with a GaAs pixel digital detector. IEEE Transactions on Nuclear Science, Vol. 47 (4), p. 1478-1482. ISSN 0018-9499. Article.
A digital mammography system based on a GaAs pixel detector has been developed by the INFN (Istituto Nazionale di Fisica Nucleare) collaboration MED46. The high atomic number makes the GaAs a very efficient material for low energy X-ray detection (10-30 keV is the typical energy range used in mammography). Low contrast details can be detected with a significant dose reduction to the patient. The system presented in this paper consists of a 4096 pixel matrix built on a 200 μm thick semi-insulating GaAs substrate. The pixel size is 170×170 μm2 for a total active area of 1.18 cm2 . The detector is bump-bonded to a VLSI front-end chip which implements a single-photon counting architecture. This feature allows to enhance the radiographic contrast detection with respect to charge integrating devices. The system has been tested by using a standard mammographic tube. Images of mammographic phantoms will be presented and compared with radiographs obtained with traditional film/screen systems. Monte Carlo simulations have been also performed to evaluate the imaging capability of the system. Comparison with simulations and experimental results will be shown.
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