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DOI: 10.1055/s-0044-1798241
MANUFACTURE AND CHARACTERIZATION OF A BOLUS, COMPOSED OF WATER, BIDISTILED GLYCERIN, GELATIN AND FORMALDEHYDE
Authors
Bolus has been used in radiotherapy for years, as a compensator for human tissue in treatments of surface tumors using photons or electrons. It is proposed in this work an optimized recipe for a non-commercial and low cost bolus, composed, of: water, bidistiled glycerin (with density of 1,25 g/cm3), gelatin and a solution of 10% formaldehyde. Fourteen samples were manufactured, where the amounts of water and glycerin were varied, while the quantities of gelatin and formaldehyde had been kept constant at 75 g and 5 cm3, respectively. For all samples was measure homogeneity, malleability and mass density. The latter was evaluated by direct measurement and by evaluating the average Housenfield unit values (HU) with tomographic images using the EclipseTM version 13,5, treatment planing system, from Varian Medical Systems, considering a region of interest of 20x20 pixels for three different sections of the samples. The measured of HU was also used to determine the homogeneity of the samples. The malleability was estimated qualitatively by three researchers. After the measured, the samples that more fit as bolus were selected for a dosimetric evaluation. The results classified the samples M and N for analysis of their dosimetric characteristics. The percentage deep dose (PDD) of both samples, M and N, was measured for 6 MV photon beam and 6 MeV and 18 MeV electron beam, these were compared to the PDD an PTW RW3 solid water phantom with the same energies. The comparison showed differences of less than 6% in the PDD values at depths less than 1,5 cm, except for the 6 MeV electron beam, which for the sample N was 17%. The sample M presented the best results for all energies and was defined the best recipe among the samples studied in this work. The recipe is 400 cm3 of water, 300 cm3 of bidistiled glycerin, 75 g of gelatin and 5 cm3 of formaldehyde.
Publikationsverlauf
Artikel online veröffentlicht:
23. Oktober 2019
© 2019. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution 4.0 International License, permitting copying and reproduction so long as the original work is given appropriate credit (https://creativecommons.org/licenses/by/4.0/)
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Carlla da Motta Oliveira, Fábio Fernando Brüning, Jessé Gevezier Prado Lyra, Susan Yamamoto Zanetti, Melissa Funchal, Tatiane Cristina de Oliveira Fernandes. MANUFACTURE AND CHARACTERIZATION OF A BOLUS, COMPOSED OF WATER, BIDISTILED GLYCERIN, GELATIN AND FORMALDEHYDE. Brazilian Journal of Oncology 2019; 15.
DOI: 10.1055/s-0044-1798241