Application of optically stimulated luminescence technique to evaluate simultaneously accumulated and single doses with the same dosimeter

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2014-02-01
Autores
Malthez, Anna Luiza M. C.
Freitas, Marcelo B. [UNIFESP]
Yoshimura, Elisabeth M.
Button, Vera L. S. N.
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Optically stimulated luminescence dosimeters (OSLD) can be read several times with a negligible loss (degradation) of signal. in this work, we explore this OSL property to estimate simultaneously the accumulated and single doses using a unique Al2O3 dosimeter, irradiated repeated times along over 4 months. This was done through several irradiations of OSLD (Landauer Luxel Dots) with two energies (28 keV X-rays and 1.25 MeV Co-60 gamma rays) and several doses distributed over time. Thermoluminescent dosimeters (TLD) were used as a reference to compare the estimated doses obtained with OSLO. for each irradiation, and both energies, a calibration curve was evaluated with OSLD and TLD to estimate the dose values. the OSL readouts were made with a MicroStar (Landauer) OSL reader. To estimate background (BG) over time, a set of OSLD and TLD (Bycron TLD100) was not irradiated and BC was monitored at each readout section. After irradiations, the OSL and TL signals were converted to dose and values were compared. As a set of OSLO suffered no bleaching after the readouts, it was possible to estimate simultaneously the accumulated and single doses with a unique OSLD. Each single dose was estimated through the subtraction of successive accumulated doses determined for each single OSLO. We concluded that the single doses determined by OSL and TL techniques were compatible, and that the accumulated dose, obtained with OSL technique was comparable to the sum of single doses determined with TLD. We can conclude that using OSL technique and Al2O3 dosimeters it is possible to estimate simultaneously accumulated and single doses with the same dosimeter irradiated with low or high energy photons. (C) 2013 Elsevier B.V. All rights reserved.
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Radiation Physics and Chemistry. Oxford: Pergamon-Elsevier B.V., v. 95, p. 134-136, 2014.