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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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