Geant4 Applicability And Validation For Photons And Electrons In Radiotherapy

The study of interaction of radiation with matter is a field of great interest in the medical physics. The computational simulation tools as Monte Carlo have been used in this field. The Geant4 code is a toolkit that incorporates several physical processes and particles which allow its application in medical physics, in particular, in the area of radiotherapy. In this work we performed simulations of monoenergetic electrons and photons beams in the energy range used in radiotherapy, and compared the results with results already published and others methods largely tested. The simulated results of range and stopping power of electrons were very close of published, the simulated results to photons results presentaccuracies <1% showing that Geant4 is appropriated to electrons and photons simulations with energy in the range of radiotherapy. © 2013 Springer.33 IFMBE12561259SKAN AG,Materialise NV,Bavarian Minist. Econ., Aff., Infrastruct., Transp. Technol.,Bavarian Bureau for International Business Relations GmbH,AKUD - Med Pharm GmbHNahum, A.E., Overview of Photon and Electron Monte Carlo (1988) Monte Carlo Transport of Electrons and Photons, pp. 3-20. , Ed: Theodore M. Jenkins, Walter R. Nelson e Alessandro Rindi, Plenum Press, New York LondonAmako, K., Agostinelli, S., Allison, J., Axen, D., Arce, P., Asai, M., Broglia, L., Boudreau, J., Geant4 - A simulation tool kit (2003) Nuclear Instruments and Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 506, pp. 250-303User's Guide, , http://geant4.cern.ch/Poon, E., Verhaegen, F., Accuracy of the photon and electron physics in GEANT4 for radiotherapy application (2005) Phys Med. Biol, pp. 1696-1711Johns, H.E., Cunningham, J.R., (1983) The Physics of Radiology, , Thomas BooksRange Tables, , http://physics.nist.gov/PhysRefData/Star/Text/ESTAR.htm

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

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 Ltd. All rights reserved.9513413

Development and Proposal of an Institutional Safety Program in the Operation of Laser Systems

Laser radiation can cause undesirable biological effects on living beings; although it is not ionizing, this type of radiation can cause burns to the skin and cornea, even cataracts, depending on the wavelength and intensity of the laser radiation. Due to the wide growth of laser applications in several areas, such as research and development, services, and industry, the occupational risks concerning this non-ionizing radiation have increased considerably worldwide. Several countries have normative documents and regulatory bodies or agencies that approach occupational safety and quality regarding laser application, equipment, and machines. In Brazil, there is a lacking of laser safety documents published by a national regulatory council. Therefore, large technological centers and educational institutions, such as SENAI Institute for Innovation in Laser Manufacturing and Processing Systems (ISI-Joinville) and the Federal Technological University of Paraná (UTFPR), do not have an institutional safety program for laser operations, and to adapt to the most modern international recommendations they look for international documents and models from other institutions. The main objective of this work was to develop and propose an institutional program following Brazilian regulatory documents from the Ministry of Labor and Social Security and the most modern international standard about laser safety from the American National Standards Institute (ANSI-Z 136-1: 2014). The developed safety program was applied to ISI-Joinville, but a model was adapted to be implemented at any research center and university

Spectroscopy Of The Gamma And X Ray Leakage Radiation From The Built-in Sources Of A Risø Tl/osl Reader

In this work we evaluate the intensity and the spectral shape of the leakage radiation from the built-in beta and alpha sources of a Risø TL/OSL reader. LiF (TLD-100), fluorite-based pellets and Al2O3:C detectors were used in order to determine the dose rate delivered to the dosimeters when the sources are closed. The leakage spectra under both alpha and beta sources were registered with a CdTe semiconductor detector. The spectrum measured under the beta source shows the X-ray beam generated by the interaction of the beta particles with the lead used to shield the source. Besides, the 59.4 keV gamma ray from 241Am was registered under the alpha source. Dose rates from 50 to 100 μGy/h were obtained for the dosimeter positions in the turntable under the beta and the alpha sources with the luminescent dosimeters. © 2014 Elsevier Ltd. All rights reserved

Osl And Tl Techniques Combined In A Beryllium Oxide Detector To Evaluate Simultaneously Accumulated And Single Doses

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Optically stimulated luminescence (OSL) and thermoluminescence (TL) are similar techniques widely used in radiation dosimetry. The main difference between these techniques is the stimulus to induce luminescence emission: TL technique uses thermal stimulation, whereas OSL uses optical stimulation. One of the main intrinsic characteristics of the OSL technique is the possibility of reading several times the dosimetric materials with a negligible loss of signal. In the case of BeO, recent studies have shown that TL stimulation up to 250 degrees C does not affect its OSL signal. Taking the advantages of dosimetric characteristics of BeO combined with both techniques, in this study, we demonstrated the possibility of measuring accumulated and single doses in the same BeO-based detector in order to use it to improve individual monitoring of radiation workers exposed to X-ray or gamma-ray fields. Single doses were measured using TL technique by heating the detector up to 250 degrees C, whereas accumulated doses were estimated using OSL technique in the same detector in a relatively short time of optical stimulation. The detectors were exposed to two energies: 28 keV X-rays and 1.25 MeV Co-60 gamma rays. The doses estimated by OSL and TL of BeO (Thermalox 995) were compared with those obtained with LiF (TLD-100) and recorded with a calibrated ionization chamber. The results indicate that combined OSL and TL signals of BeO detectors can provide additional information of accumulated dose, with additional exploration of the advantages of both techniques, such as speed in readouts with OSL, and double-check the doses using TL and OSL intensities from BeO. (C) 2016 Elsevier Ltd. All rights reserved.110155159State of Sao Paulo Research Foundation FAPESP/Brazil [2010/16437-0]Coordination for the Improvement of Higher Education Personnel (CAPES/Brazil)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

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

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 photons9513413

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

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.Univ Estadual Campinas, Sch Elect & Comp Engn, Dept Biomed Engn, Campinas, SP, BrazilUniversidade Federal de São Paulo, Hlth Informat Dept, São Paulo, BrazilUniv São Paulo, Dept Nucl Phys, São Paulo, BrazilUniversidade Federal de São Paulo, Hlth Informat Dept, São Paulo, BrazilWeb of Scienc

Experimental photon energy response of different dosimetric materials for a dual detector system combining thermoluminescence and optically stimulated luminescence

Precise knowledge of the energy response of radiation detector materials is necessary for accurate dose measurements, because the usual TL and OSL material response relative to the medium of interest (air, water or tissue) varies with beam energy. in this work, we experimentally evaluated the photon energy dependence of different materials used as detectors (Al2O3:C Luxel, BeO Thermalox 995, LiF:Mg,Ti-TLD100 and Brazilian pellets based on CaSO4:Dy and CaF2:natural) in personal dosimetry through OSL and techniques, using optimized readout parameters for each material and radiation qualities similar to real situations of exposure. It is well known that depending on the material's effective atomic number and type of stimulation, the photon energy response can present either an under-response relative to air in the low energy range, as is the case of BeO, or a large over-response, as Al2O3, CaSO4 and CaF2, or even a very fiatresponse, as LiF. By utilizing intrinsic characteristics of these materials combined with OSL and TL techniques, we evaluated ratios of relative photon energy responses between pairs of OSL (OSLD) and TL(TLD) detectors. We have noted that for all combinations of materials (Al2O3/LiF, CaSO4/BeO, and CaF2/BeO), the ratio of energy responses of each pair did not change significantly with energy in the intervals below 50 or above 300 keV. On the other hand, in the range of energies between 50 and 300 keV, there was a strong change in the ratio values, indicating that the ratio of detector responses well-discriminates the incident photon energy. By using these outcomes, it was possible to apply dose corrections with respect to energy using ratios of OSL and TL signals of dosimeters exposed to unknown radiation beam qualities and to determine doses in a blind test. Our results point out that this methodology could be employed to correct photon energy responses of a personal dosimeter based on both OSL and TL techniques. OSL advantages (fast readout, possibility of various partial readings and of determining accumulated doses) would be associated with the TL ones (large variety of dosimeters commercially available and use of glow curve as a readout quality control) in a dual detector system capable of determining photon energy and dose, without using attenuation filters. This new methodology might improve dose evaluation in personal dosimetry. (C) 2014 Elsevier B.V. All rights reserved.Univ Estadual Campinas, Sch Elect & Comp Engn, Dept Biomed Engn, São Paulo, BrazilUniversidade Federal de São Paulo, Hlth Informat Dept, São Paulo, BrazilUniv São Paulo, Dept Nucl Phys, São Paulo, BrazilUniversidade Federal de São Paulo, Hlth Informat Dept, São Paulo, BrazilWeb of Scienc