7 research outputs found

    Three-dimensional dose reconstruction of breast cancer treatment using portal imaging

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    In this study, we present an algorithm for three-dimensional (3-D) dose reconstruction using portal images obtained with an electronic portal imaging device (EPID). For this purpose an algorithm for 2-D dose reconstruction, which was previously developed in our institution, was adapted. The external contour of the patient was used to correct for absorption of primary photons, but the presence of inhomogeneities was not taken into account. The accuracy of the algorithm was determined by irradiating two anthropomorphic breast phantoms with 6 MV photons. The dose values derived from portal images were compared with results from 3-D dose calculations, which, in turn, were verified with data obtained with an ionization chamber and film dosimetry. It was found that the application of contour information significantly improves the accuracy of 2-D dose reconstruction. If the total dose at the isocenter plane resulting from all treatment beams is reconstructed, the average deviation from the planned dose is 0.1%+/-1.7% (1 SD). If contour information is not available, the differences increase up to +/-20% for the individual beams. In that case, the dose can only be reconstructed with reasonable accuracy when (nearly) opposing beams are used. The average deviation of the 3-D reconstructed dose from the planned dose in the irradiated volume is 1.4%+/-5.4% (1 SD). If the irradiated volume is enclosed by planes less than 5 cm distant from the isocenter plane, then the average deviation is only 0.5%+/-3.4% (1 SD). It can be concluded that the proposed algorithm for a 3-D dose reconstruction allows a determination of the dose at the isocenter plane and the dose-volume histogram with an accuracy acceptable for an independent verification of the treatmen

    Tricellulin Expression and its Prognostic Significance in Primary Liver Carcinomas.

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    Numerous data suggest that altered expression of tight junction proteins such as occludin and claudins plays important role in carcinogenesis. However, little is known about tricellulin, a transmembrane tight junction protein concentrated where three epithelial cells meet. We aimed to characterize tricellulin expression in normal and cirrhotic liver in comparison to primary hepatic neoplasms. Tricellulin expression of 20 control livers, 12 cirrhotic livers, 32 hepatocellular carcinomas (HCC), and 20 intrahepatic cholangiocarcinomas (iCCC) was investigated by immunohistochemistry and Western blotting. Co-localization of tricellulin with claudin-1, -4, and MRP2 was studied using double immunofluorescence. Scattered tricellulin immunopositivity was restricted to biliary pole of hepatocytes confirmed by co-localization with MRP2. Moreover, spotted-like reaction was observed between bile duct epithelial cells. In 40 % of HCCs marked tricellulin overexpression was measured regardless of tumor grades. In iCCCs, however, tricellulin expression decreased parallel with dedifferentiation. In HCCs high tricellulin expression, in iCCCs low tricellulin expression correlated with poor prognosis. Co-localization with MRP2 might substantiate that tricellulin plays role in blood-biliary barrier. Overexpressed tricellulin in a subset of HCCs correlated with unfavorable prognosis. Similar to ductal pancreatic adenocarcinoma, higher grades of iCCCs were associated with decreased tricellulin expression correlating with poor prognosis
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