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Potential of Dose Reduction for Bedside Chest Radiography by the use of Additional Filters

出版	Fachhochschule Wiener Neustadt, 2019
URL	http://books.google.com.hk/books?id=76zizQEACAAJ&hl=&source=gbs_api

註釋Radiation exposure caused by radiographs depends on the averaged organ equivalent dose and the tissue weighting factor of the affected organs. The proportion of absorbed energy depends strongly on the beam quality. By the use of additional filters, the x-ray spectrum can be hardened. The increase in mean photon energy causes the proportion of the absorbed dose to decrease. This leads to a reduction of the radiation exposure but also to a lower image contrast. In particular, the dose burden of superficially located organs can be reduced by additional filters. This study is based on the assumption, that by using an additional filter (0.2 mm Cu + 1 mm Al) the effective dose of bedside chest x-ray could be significantly reduced, because a large part of the dose burden is due to the breast dose, which will be greatly shortened by beam hardening. The aim of this study was therefore to ascertain the effective dose of bedside chest x-ray without and with additional filters, while keeping the detector entrance dose fixed. In addition, the effects on image quality were examined. The determination of the effective dose was made in two different ways. First, Thermoluminescence Dosimetry (TLD) measurements were performed in an anthropomorphic phantom (Alderson Rando phantom). On the other hand, a determination of the effective dose using Monte Carlo simulation (PCXMC-software) was made. The initial value of effective dose without additional filtering was determined to be 40.3 Sv (TLD-measurement) respectively 25.7 Sv (Monte Carlo simulation). The use of additional filters leads to a reduction of the effective dose by 62% (TLD-measurement) respectively 28% (Monte Carlo simulation). In the visual assessment of the radiographs, there were no significant differences in image quality.*****Radiation exposure caused by radiographs depends on the averaged organ equivalent dose and the tissue weighting factor of the affected organs. The proportion of absorbed energy depends strongly on t