13 March 2009 Image quality evaluation of direct-conversion digital mammography system with new dual a-Se layer detector
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Proceedings Volume 7258, Medical Imaging 2009: Physics of Medical Imaging; 72584P (2009) https://doi.org/10.1117/12.811469
Event: SPIE Medical Imaging, 2009, Lake Buena Vista (Orlando Area), Florida, United States
Abstract
To increase the detection performance of breast cancers in mammograms, we need to improve shape delineation of micro calcifications and tumors. We accomplished this by developing a direct-conversion mammography system with an optical reading method and a new dual a-Se layer detector. The system achieved both small pixel size (50 micrometer) and a high Detective Quantum Efficiency (DQE) realized by 100 % of fill factor and noise reduction. We evaluated image quality performance and determined the best exposure conditions. We measured DQE and Modulation Transfer Function(MTF) according to the IEC62220-1-2. High DQE was maintained at a low radiation dosage, indicating that the optical reading method accompanies low noises. Response of MTF was maintained at up to the Nyquist frequency of 10 cyc/mm, which corresponds to 50 micrometer pixel size. To determine the best exposure conditions, we measured Contrast to Noise Ratio (CNR) and visually evaluated images of a resected breast under conditions of MoMo, MoRh, and WRh. There were occasional disagreements between the exposure conditions for achieving the maximum CNR and those for the best image graded by the visual evaluation. This was probably because CNR measurement does not measure effects of scattered X-ray. The images verified the improvement in detection and delineation performance of micro calcifications and tumors.
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Takao Kuwabara, Takao Kuwabara, Nobuyuki Iwasaki, Nobuyuki Iwasaki, Tomonari Sendai, Tomonari Sendai, Ryosuke Furue, Ryosuke Furue, Toshitaka Agano, Toshitaka Agano, } "Image quality evaluation of direct-conversion digital mammography system with new dual a-Se layer detector", Proc. SPIE 7258, Medical Imaging 2009: Physics of Medical Imaging, 72584P (13 March 2009); doi: 10.1117/12.811469; https://doi.org/10.1117/12.811469
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