1 April 2014 The beam stop array method to measure object scatter in digital breast tomosynthesis
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Abstract
Scattered radiation is inevitably generated in the object. The distribution of the scattered radiation is influenced by object thickness, filed size, object-to-detector distance, and primary energy. One of the investigations to measure scatter intensities involves measuring the signal detected under the shadow of the lead discs of a beam-stop array (BSA). The measured scatter by BSA includes not only the scattered radiation within the object (object scatter), but also the external scatter source. The components of external scatter source include the X-ray tube, detector, collimator, x-ray filter, and BSA. Excluding background scattered radiation can be applied to different scanner geometry by simple parameter adjustments without prior knowledge of the scanned object. In this study, a method using BSA to differentiate scatter in phantom (object scatter) from external background was used. Furthermore, this method was applied to BSA algorithm to correct the object scatter. In order to confirm background scattered radiation, we obtained the scatter profiles and scatter fraction (SF) profiles in the directions perpendicular to the chest wall edge (CWE) with and without scattering material. The scatter profiles with and without the scattering material were similar in the region between 127 mm and 228 mm from chest wall. This result indicated that the measured scatter by BSA included background scatter. Moreover, the BSA algorithm with the proposed method could correct the object scatter because the total radiation profiles of object scatter correction corresponded to original image in the region between 127 mm and 228 mm from chest wall. As a result, the BSA method to measure object scatter could be used to remove background scatter. This method could apply for different scanner geometry after background scatter correction. In conclusion, the BSA algorithm with the proposed method is effective to correct object scatter.
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Haeng-hwa Lee, Ye-seul Kim, Hye-Suk Park, Hee-Joung Kim, Jae-Gu Choi, Young-Wook Choi, "The beam stop array method to measure object scatter in digital breast tomosynthesis", Proc. SPIE 9033, Medical Imaging 2014: Physics of Medical Imaging, 903363 (1 April 2014); doi: 10.1117/12.2043348; https://doi.org/10.1117/12.2043348
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