Development of an optically stimulated luminescent detector for personal and medical dosimetry

Abstract

Optically Stimulated Luminescence (OSL) is one of the main techniques in use for medical and personal dosimetry and it is rapidly substituting thermoluminescence (TL) because its advantages over TL. These advantages are due to the optical nature of the entire system, that allows among other things, build robust detector encapsulate in plastic sheets, since it does not requires heat to read the detector like TL technique. The method also preserves the detector's integrity, as well as the dosimetric signal, and thus allowing multiple readings without upset significantly the signal. These characteristics translate into high reliability and better cost effective, compared to TL. On the other hand, the lack of variety of commercially available materials is considered a disadvantage of OSL technique. In fact, there are only two detectors commercially available, namely, A2O3:C, supplied by Landauer Inc and BeO, supplied by Brush Ceramics Products Materion Co. This lack of competition allows these companies commercializes their product with high prices in the national market. These facts justify an investment in the search for new OSL material for dosimetric purpose. The new detector, however, needs to fulfill all dosimetric features suitable for personal dosimetry requested by the regulating agencies. Despite OSL dosimetry has been performed along the last decade in several countries, including Brazil, only in 2015 the company Sapra-Landauer obtained license from the "Comissão Nacional de Energia Nuclear (CNEN)" to utilize the OSL technology for external dosimetry. This proposal consists in developing a OSL dosimeter, in a pilot scale, in all stages: material's synthesis, detector's fabrication and characterization of its physical and dosimetric properties. The investigated material is based on magnesium oxide, a material that has been long ago proposed as a TL dosimeter, but it had been discarded because the signal's instability. New investigations using a different fabrication process, however, showed that this material may became a suitable OSL dosimeter, because it showed high sensitivity and signal stability. It is expected that the product to be developed meets the quality standards currently required and that, with the increase of the installed capacity and the optimization of the production process, can not only satisfy the existing market demand, producing on an industrial scale, meet the demand with a competitive price. Above all, it is expected that the development of this technology will also have a positive impact on society and may serve as an incentive to control working conditions in the areas of ionizing radiation applications. These are the main challenges that the project intends to overcome, aiming to obtain, at the end, a fully characterized dosimeter with respect to its relevant structural and dosimetric properties. (AU)