PATRICIA BERINGHS RIO

PATRICIA BERINGHS RIO

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Radiosurgery dosimetry using CaSO4:Eu OSLD film
2023 - GASPARIAN, PATRICIA B.R.; MALTHEZ, ANNA L.M.C.; TORQUATO, MICHELE; CAMPOS, LETICIA L.
Recent studies demonstrated that optically stimulated luminescence (OSL) systems allow the evaluation of doses for 2D mapping in a relatively fast and simple way and results show submillimeter resolution. This work presents, for the first time, an optically stimulated luminescence dosemeter (OSLD) in the form of film made with CaSO4:Eu particles embedded in a silicone elastomer matrix. The OSLD film was produced using a low-cost and relatively simple methodology. This film is reusable and the signal can be satisfactorily bleached using blue LEDs. The main dosimetric properties were evaluated using TL/OSL Risø reader with blue stimulation and Hoya U-340 filter. Investigation shows repeatability within 3% when measuring with the same film sample. Regarding the OSLD film homogeneity, nearly 12% sensitivity change was observed within the 5 × 5 cm2 produced film. Additionally, the dose response curve shows linearity from 5 to 25 Gy. Fading of the OSL signal is relatively high, about 50% in the first week and then is stable. Nevertheless, a 3 × 3 cm2 OSLD film was successfully used to map dose distribution in radiosurgery (6 MV photon beam). This work demonstrates the feasibility of 2D dosimetry using reusable OSLD films based on CaSO4:Eu.
An overview study on the TL and OSL dosimetry patent processes over time
2023 - GASPARIAN, P.B.R.; MALTHEZ, A.L.M.C.; MARIANO, L.; CAMPOS, L.L.; POLITANO, R.
Since its discovery, ionizing radiation has been used in many different applications. Materials and methods have been developed to measure and quantify radiation doses. Thermoluminescence (TL) and Optically Stimulated Luminescence (OSL) are two techniques used for radiation dosimetry. Both TL and OSL are primarily applied in several areas, such as dating of ancient materials, equipment quality control and individual monitoring. One of the parameters to measure the knowledge and development of a technology is the number of patents related to the field. In this work, we established a methodology for patent search on the World Intellectual Property Organization (WIPO) database aiming to review the development of TL and OSL dosimetry over time. We concluded that along with the OSL technique development, the TL technique should continue to be explored in radiation dosimetry.
Using the optically stimulated luminescence technique for one- and two-dimensional dose mapping
2022 - GASPARIAN, PATRICIA B.R.; MALTHEZ, ANNA L.M.C.; CAMPOS, LETICIA L.
In respect of radiation dosimetry, several applications require dose distribution verification rather than absolute dosimetry. Most protocols use radiological and radiochromic films and ionization chambers or diode arrays for dose mapping. The films are disposable which causes the precision of the results dependent on film production variability. The measurements with arrays of ionization chambers or diodes mainly lack spatial resolution. This review aims to provide an overview of the use of optically stimulated luminescence detectors (OSLDs) for one-dimensional (1D) and two-dimensional (2D) dose mapping in different applications. It reviews the ideas, OSL materials, and applications related to the assessment of dose distribution using OSLDs in the form of film or ceramic plate (BeO). Additionally, it reviews research published in the international scientific literature from 1998 to 2021. As an outcome, a table containing the main characteristics of each relevant paper is shown. The results section was divided by the type of OSL material, and we briefly described the principal findings and the significant developments of each mentioned study such as film production and OSL reader assembly. The purpose of this study was to present an overview of the main findings of several research groups on the use of OSLD in the form of film or plate for 1D and 2D dose mapping. Finally, the potential future development of dose mapping using OSLD films was outlined.
Study of the dosimetric properties of CaSO4:Dy using OSL technique
2022 - GASPARIAN, P.B.R.; MALTHEZ, A.L.M.C.; YOSHIMURA, E.M.; UMISEDO, N.K.; CAMPOS, L.L.
Calcium sulfate doped with dysprosium (CaSO4:Dy) has been used for personal dosimetry using the thermoluminescence (TL) technique for decades and its TL properties are well-known. Considering the advantages of the OSL technique (relatively simple and faster readout and detector reusability) and the potential application of CaSO4:Dy as an OSL detector, this study aimed to investigate the dosimetric properties of CaSO4:Dy using the OSL technique. The present study was carried out using CaSO4:Dy pellets prepared at IPEN irradiated and read in a TL/OSL Risø reader with blue light stimulation and Hoya U-340 filter. OSL dosimetric properties essentially dose response, reproducibility, and fading characteristics were evaluated. Moreover, TL and OSL signals were compared to study the correlation between OSL signals and TL peaks. CaSO4:Dy OSL response is linear from 0.1 to 10 Gy and shows reproducibility better than 5%. The low-temperature TL peak is unstable; however, the OSL signal seems to be associated with higher-temperature peaks.
Generation of calibrated tungsten target x-ray spectra: modified TBC model
2007 - COSTA, PAULO R.; NERSISSIAN, DENISE Y.; SALVADOR, FERNANDA C.; RIO, PATRICIA B.; CALDAS, LINDA V.E.