Build-Up PMMA Plate Effect on Calibration of TLD Reader

The routine monitoring of the occupationally exposed individuals constitutes an integral part of radiation protection program implemented at the Vinca Institute of Nuclear Sciences (INNV). The Individual monitoring service (IMS) at the INNV, accredited according to quality standard EN ISO/IEC 17025, is using Harshaw 6600 Plus automatic reader and thermoluminescent dosimeters (TLD) from two manufacturers (Harshaw, RadPro international GmbH). Working procedures are implemented according to Technical Recommendations for Monitoring Individuals Occupationally Exposed to External Radiation, RP 160 (European Commission, 2009). Among general consideration, RP 160 is suggesting that routine calibration of dosimetry system should be performed taking into consideration secondary charged particle equilibrium. As TLD system in use at IMS INNV comprises of TLD reader and of TLD cards, this consideration should be applied in both cases: when the reader and the TLD cards are being calibrated. During reader calibration, secondary charged particle equilibrium can be ensured using build-up PMMA plate of certain thickness placed in front of dosimeters. In this paper, influence of the build-up plate on reader calibration is being analyzed. This influence is observed through changes in reader calibration factor (RCF). RCF values obtained during reader calibration procedure with and without 2 mm thick build-up plate are presented. Exposures of whole body TLDs placed on slab phantom were done with Cs-137 radiation source located at Secondary Standard Dosimetry Laboratory (SSDL) at INNV. TLDs from both manufacturers had 2 detectors for measuring the dose equivalent at the depths of 10 mm and 0.07 mm. TLD reader was calibrated to measure effective dose in terms of Hp(10) and local skin dose in terms of Hp(0.07). RCF values for detectors measuring Hp(10), from both manufacturers, when irradiated without the plate were around 5% higher than RCF values obtained when irradiations were done with the plate. Values of RCFs for detectors measuring Hp(0.07) were around 1% higher when the plate had not been used. As RCF value is inversely proportional to measured dose, reader calibration without build-up plate, in terms of Hp(10), would lead to underestimated dose values. The observed RCF deviation of Hp(0.07) detector is regarded as consequence of exposure conditions uncertainties. In conclusion, if a constant geometry and constant operational conditions of TLDs are achieved, the only part of the TLD system that is not stable for a long time period is the TLD reader. To avoid inaccurate results, RCF should be orderly checked and reader calibration should be done according to widely accepted standards, currently in effect.3rd International Conference on Radiation and Applications in Various Fields of Research (RAD), Jun 08-12, 2015, Budva, Montenegr

Build-Up PMMA Plate Effect on Calibration of TLD Reader

The routine monitoring of the occupationally exposed individuals constitutes an integral part of radiation protection program implemented at the Vinca Institute of Nuclear Sciences (INNV). The Individual monitoring service (IMS) at the INNV, accredited according to quality standard EN ISO/IEC 17025, is using Harshaw 6600 Plus automatic reader and thermoluminescent dosimeters (TLD) from two manufacturers (Harshaw, RadPro international GmbH). Working procedures are implemented according to Technical Recommendations for Monitoring Individuals Occupationally Exposed to External Radiation, RP 160 (European Commission, 2009). Among general consideration, RP 160 is suggesting that routine calibration of dosimetry system should be performed taking into consideration secondary charged particle equilibrium. As TLD system in use at IMS INNV comprises of TLD reader and of TLD cards, this consideration should be applied in both cases: when the reader and the TLD cards are being calibrated. During reader calibration, secondary charged particle equilibrium can be ensured using build-up PMMA plate of certain thickness placed in front of dosimeters. In this paper, influence of the build-up plate on reader calibration is being analyzed. This influence is observed through changes in reader calibration factor (RCF). RCF values obtained during reader calibration procedure with and without 2 mm thick build-up plate are presented. Exposures of whole body TLDs placed on slab phantom were done with Cs-137 radiation source located at Secondary Standard Dosimetry Laboratory (SSDL) at INNV. TLDs from both manufacturers had 2 detectors for measuring the dose equivalent at the depths of 10 mm and 0.07 mm. TLD reader was calibrated to measure effective dose in terms of Hp(10) and local skin dose in terms of Hp(0.07). RCF values for detectors measuring Hp(10), from both manufacturers, when irradiated without the plate were around 5% higher than RCF values obtained when irradiations were done with the plate. Values of RCFs for detectors measuring Hp(0.07) were around 1% higher when the plate had not been used. As RCF value is inversely proportional to measured dose, reader calibration without build-up plate, in terms of Hp(10), would lead to underestimated dose values. The observed RCF deviation of Hp(0.07) detector is regarded as consequence of exposure conditions uncertainties. In conclusion, if a constant geometry and constant operational conditions of TLDs are achieved, the only part of the TLD system that is not stable for a long time period is the TLD reader. To avoid inaccurate results, RCF should be orderly checked and reader calibration should be done according to widely accepted standards, currently in effect.3rd International Conference on Radiation and Applications in Various Fields of Research (RAD), Jun 08-12, 2015, Budva, Montenegr

Chemical composition and screening of the antimicrobial and antioxidative activity of extracts of Stachys species

GC and GC/MS analyses of the diethyl ether and ethyl acetate extracts obtained from the aerial parts of Stachys germanica subsp. heldreichii (Boiss) Hayek, Stachys iva Griseb., Stachys plumosa Griseb. and Stachys scardica Griseb., Balkan peninsula endemics, were performed. One hundred and seventy-nine constituents, accounting for 88.8–98.1% of the total composition of the extracts, were identified. The common feature of the diethyl ether extracts was the high content of terpenoids and fatty acid-derived compounds, while the common feature of the ethyl acetate extracts was the prevalence of fatty acid-derived compounds. A disk diffusion method was used for the evaluation of the antimicrobial activities of the extracts against a panel of microorganisms (bacteria: Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Salmonella enteritidis; fungi: Aspergillus niger and Candida albicans). The total antioxidant capacity of the extracts was evaluated by the phosphomolybdenum method. The preliminary bioassay results indicated that the diethyl ether extract of S. plumosa could be a possible source of antioxidant and antimicrobial compounds

Assessment of Occupational Dose in Fluoroscopy Procedures When Individual Monitoring Is Not Utilized

Fluoroscopy procedures may lead to increased radiation exposure of radiologists and other staff members. The objective of the study is to assess whole body radiation doses and doses to the eye in fluoroscopy procedures, based on measurements that allow for estimates of occupational doses when personal dosimeters have not been used. Four geometrical configurations were considered: overcouch x-ray tube with and without table mounted lead rubber curtains in place, undercouch x-ray tube with horizontal x-ray beam and undercouch x-ray tube with vertical x-ray beam. The doses were estimated using distribution of the scattered radiation and typical workload, as well as the pattern of used of protective tools. Estimated effective dose was in the range from few to 60 mu Sv per procedure for radiologist, and from few to 20 mu Sv per procedure for radiographer, depending on the geometrical configuration and level of personal protection. Corresponding unprotected eye doses were estimated to be in the range 0.03 - 2.8 mSv per procedure for radiologist and 0.02-0.78 mSv for radiographer. The presented results allowed for realistic estimations of the occupational whole body dose and dose to the eyes from the workload of the staff members and from the level of use of radiation protection tools when personal dosimeters have not been regularly used.3rd International Conference on Radiation and Applications in Various Fields of Research (RAD), Jun 08-12, 2015, Budva, Montenegr

Contamination of the Šar Mountains Aquatorium – Kosovo with Depleted Uranium

The main objective of this study was to estimate the environmental and health risk of the Šar Mountains (Kosovo) for depleted uranium contamination. The risk assessment of the contamination is needed since, in the spring of 1999, conflict with bombarding took place in the territory of the Western Balkans, during which depleted uranium ammunition was used. In Serbia and Montenegro, such tests were performed; based on them, some territories were decontaminated. Šar Mountains is particularly important as it is one of the few water-rich areas in Kosovo. Therefore, soil and water samples were taken from characteristic places in the Šar Mountains aquatorium. Tests of the samples were performed under well-controlled conditions. The measurement uncertainty was less than 5%. Based on the obtained results, it was concluded that there was no contamination of the Šar Mountains with depleted uranium. This conclusion can be extended to the broader area around the Šar Mountains, as it is a safe area surrounded by high mountains

The Effect of Liquid-Phase Exfoliated Graphene Film on Neurodifferentiation of Stem Cells from Apical Papilla

Background: Dental stem cells, which originate from the neural crest, due to their easy accessibility might be good candidates in neuro-regenerative procedures, along with graphene-based nanomaterials shown to promote neurogenesis in vitro. We aimed to explore the potential of liquid-phase exfoliated graphene (LPEG) film to stimulate the neuro-differentiation of stem cells from apical papilla (SCAP). Methods: The experimental procedure was structured as follows: (1) fabrication of graphene film; (2) isolation, cultivation and SCAP stemness characterization by flowcytometry, multilineage differentiation (osteo, chondro and adipo) and quantitative PCR (qPCR); (3) SCAP neuro-induction by cultivation on polyethylene terephthalate (PET) coated with graphene film; (4) evaluation of neural differentiation by means of several microscopy techniques (light, confocal, atomic force and scanning electron microscopy), followed by neural marker gene expression analysis using qPCR. Results: SCAP demonstrated exceptional stemness, as judged by mesenchymal markers’ expression (CD73, CD90 and CD105), and by multilineage differentiation capacity (osteo, chondro and adipo-differentiation). Neuro-induction of SCAP grown on PET coated with graphene film resulted in neuron-like cellular phenotype observed under different microscopes. This was corroborated by the high gene expression of all examined key neuronal markers (Ngn2, NF-M, Nestin, MAP2, MASH1). Conclusions: The ability of SCAPs to differentiate toward neural lineages was markedly enhanced by graphene film

The prevalence of the most important viral infections in renal transplant recipients in Serbia

Viruses are the main cause of opportunistic infections after kidney transplantation. The aim of this study was to determine the prevalence of cytomegalovirus (CMV), Epstein-Barr virus (EBV), B. K. virus (BKV) and John Cunningham virus (JCV) infections in renal transplant recipients (RTR). This retrospective study of 112 RTR investigated the presence of CMV, EBV and polyomaviruses DNA in plasma and/or urine by PCR. The visualization of PCR products was performed by electrophoresis on 2% agarose gel stained with ethidium bromide and photographed under a UV light. The chi-square test was used for statistical analysis. CMV DNA was detected in 14/112 (12.5%), EBV DNA in 4/49 (8.16%), BKV DNA in 10/31 (32.26%) and JCV DNA in 3/31 (9.68%) RTR. These results show that CMV infection is more often present in RTR compared to other investigated viral infections. In the light of these results, molecular testing could be useful in identifying recipients at high risk of symptomatic post-transplant viral infection. [Projekat Ministarstva nauke Republike Srbije, br. 175073, br. 175038 and br. 175089

Influence of nuclear radiation and laser beams on optical fibers and components

The influence of nuclear radiation and particles has been the object of investigation for a long time. For new materials and systems the research should be continued. Human activities in various environments, including space, call for more detailed research. The role of fibers in contemporary communications, medicine, and industry increases. Fibers, their connections and fused optics components have one type of tasks - the transmission of information and power. The other type of tasks is reserved for fiber lasers: quantum generators and amplifiers. The third type of tasks is for fiber sensors, including high energy nuclear physics. In this paper we present some chosen topics in the mentioned areas as well as our experiments with nuclear radiation and laser beams to fiber and bulk materials of various nature (glass, polymer, metallic, etc.)

Dosimetry audit in radiotherapy centers in Serbia in 2016

U svrhu ispravne procene apsorbovanih doza za pacijente pri radioterapiji primenom polja gama zračenja (Co-60) kao i visokoenergetskih polja X-zračenja generisanih u linearnim akceleratorima, veći broj radioterapijskih centara iz Srbije je učestvovao u programu IAEA/WHO Postal Dose Quality Audit. Radiofotoluminescentni dozimetri (RPLD) su u okviru ovog programa postavljani u 15 polja X-zračenja različitih energija i jedno polje gama zračenja (Co-60) u različitim ustanovama, radi komparativne procene apsorbovane doze u vodi. Program je sproveden u periodu februar-maj 2016. godine.In order to accurately assess the absorbed dose delivered to the patients during the radiotherapy procedures, where Co-60 gamma radiation fields and high-energy X-ray radiation fields are employed, many of the radiotherapy centers in Serbia participated in the IAEA/WHO Postal Dose Quality Audit Program. Radio photoluminescent dosimeters were irradiated in 15 different X-ray ionizing radiation fields of various energies, and one gamma-ray radiation field (Co-60) in different radiotherapy centers. The study was performed in the period from February to May 2016.Зборник радова : XXIX симпозијум ДЗЗСЦГ : Сребрно језеро, 27-29. септембар 2017. годин