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

Characteristics of local pulmonary response following intranasal application of Aspergillus fumigatus conidia

In this study, histopathology of local pulmonary response following intranasal inoculation of different doses of Aspergillus fumigatus conidia in laboratory rats was evaluated. Development of response was evaluated on days seven and twenty one, following conidia inoculation by cell infiltration and by presence of A. fumigatus conidia in homogenates of lung tissue. Total and differential peripheral blood leukocyte counts and state of leukocyte adhesion/aggregation were monitored to estimate the presence of systemic response in infected individuals. Mycological examination revealed the presence of conidia in lung tissue homogenates of infected animals, with high number of non-germinating spores on day twenty one, following the inoculation of lower conidia dose. Histopathological examination revealed the presence of lymphocytes perivascularly and in vascular lumen in the lungs. Presented data demonstrate pulmonary immune response following A. fumigatus conidia administration.Aspergillus fumigatus je oportunistička gljiva koja najčešće dovodi do pulmonarnih aspergiloza kod imunokompromitovanih organizama. U ovom radu su prikazani rezultati istraživanja izazivanja infekcije aspergilusom kod pacova. U cilju dobijanja podataka o prisustvu i karakteristikama lokalnog inflamatornog odgovora u plućima određen je diferencijalni sastav leukocita periferne krvi i testirana je njihova aktivnost, izvršeni su histopatološki pregled pluća i provera prisustva spora A. fumigatus u homogenatima pluća. Naši podaci su pokazali prisustvo lokalnog odgovora u plućima posle 7 dana dok podaci dobijeni posle 21 dan ne pokazuju značajne razlike u odnosu na kontrolnu grupu. Povećani broj neklijajućih spora u homogenatu pluća sedmog dana nakon inokulacije može da se objasni prisustvom limfocitnog infiltrata u plućima i aktivnošću limfocita in situ. Povećan broj klijajućih spora 21. dana nakon inokulacije može da bude posledica kapaciteta malog broja preostalih spora da klijaju.Projekat ministarstva br. 14303

Characteristics of local pulmonary response following intranasal application of Aspergillus fumigatus conidia

In this study, histopathology of local pulmonary response following intranasal inoculation of different doses of Aspergillus fumigatus conidia in laboratory rats was evaluated. Development of response was evaluated on days seven and twenty one, following conidia inoculation by cell infiltration and by presence of A. fumigatus conidia in homogenates of lung tissue. Total and differential peripheral blood leukocyte counts and state of leukocyte adhesion/aggregation were monitored to estimate the presence of systemic response in infected individuals. Mycological examination revealed the presence of conidia in lung tissue homogenates of infected animals, with high number of non-germinating spores on day twenty one, following the inoculation of lower conidia dose. Histopathological examination revealed the presence of lymphocytes perivascularly and in vascular lumen in the lungs. Presented data demonstrate pulmonary immune response following A. fumigatus conidia administration

Review of the thermoluminescent dosimetry method for the environmental dose monitoring

Passive solid state dosimeters, such as thermoluminescence dosimeters, provide integrated measurement of the total dose and are widely used in environmental monitoring programs. The objective of this paper is to provide a comprehensive review on the use of thermoluminescent dosimetry methods for monitoring radiation dose in the environment. The article presents the part of the research results of the project PREPAREDNESS (EMPIR 2016 call for Metrology for Environment joint research project) with a particular objective to harmonize procedures used by dosimetry services, relevant authorities and Institutes across the Europe. To achieve this, different monitoring routines that are based on passive environ mental dosimetry methods are investigated. Differences in performing specific steps such as preheating, reading, annealing, minimizing fading, and others, are analyzed. The investigation was performed by means of qualitative literature review that showed the lack of information about specific steps. The conclusion of this work is that thermoluminescent dosimetry measurement system has to be type-tested even though the testing procedure is complicated. In addition to this, control dosimeters should be introduced, International Organization for Standardization protocols should be followed during calibration, and finally, parameters influencing the measurement uncertainty have to be identified and well understood in order to pro duce ac cu rate dose measurement results

EMPIR project 16ENV04 Preparedness - main goals and research directions

16ENV04 Preparedness je projekat iz poziva EMPIR 2016 za zaštitu životne sredine. Glavni cilj projekta je poboljšanje pripravnosti za nuklearne i radiološke incidente i akcidente, koji bi mogli da se dogode u budušnosti. Pripravnost će biti poboljšana tako što će se izvršiti istraživanja u nekoliko pravaca: upotreba bespilotnih letelica za radiološka merenja, upotreba mobilnih sistema za uzorkovanje vazduha, istraživanje mogućnosti korišćenja radioloških podataka iz nevladinih mreža i korišćenje sistema pasivnih dozimetara za monitoring okoline. Još jedan od načina za poboljšanje pripravnosti je smanjenje mogušnosti bezrazložne panike koja bi mogla da bude izazvana diseminacijom merenja iz nevladinih mreža i drugih izvora, što bi moglo da izazove i smanjenje poverenja u zvanične podatke. U cilju realizacije projekta, od velikog značaja su diseminacija razultata i komunikacija sa svim zainteresovanim stranama.16ENV04 Preparedness is a research project within the EMPIR 2016environment call. The main project goal is to increase the preparedness for nuclear and radiological incidents and accidents that might occur in the future. The preparedness will be increased by pursuing several directions of research: use of unmanned aerial vehicles for radiological measurements, use of transportable air-sampling systems, investigating the crowd sourced radiological data for possible official uses and investigating the use of passive dosimetry systems for ambient monitoring. Another aspect of preparedness is to try to reduce the possibility of unwarranted panic caused by the data disseminated by citizen networks and other sources and to increase confidence in official data. To realize the project goals, communication with stakeholders and dissemination of results are of greatest importance.Proceedings: [http://vinar.vin.bg.ac.rs/handle/123456789/8681]XXX симпозијум ДЗЗСЦГ (Друштва за заштиту од зрачења Србије и Црне Горе), 2- 4. октобар 2019. године, Дивчибаре, Србиј

Results of IMS participation in international intercomparisons for whole body dosemeters – 10 years of study

The regular participation of an accredited individual monitoring service (IMS) in the international and/or interlaboratory intercomparisons (IC) is required according to ISO/IEC 17025:2017 standard, General requirements for the competence of testing and calibration laboratories. By taking the part in an IC, IMS shows competence, reliability, and has an opportunity to learn further and improve its measurement method. The European Dosimetry Group (EURADOS) Working Group 2 (WG2) has acknowledged the value of the regular IC and also found that data and results from it are fundamental for the harmonization of the measurement process [1]. Thus, EURADOS started a self-sustained program of IC for IMS for external radiation on a biannual basis. The results of an accredited IMS at the Department of Radiation and Environmental Protection, “VINČA” Institute of Nuclear Sciences, Belgrade, Serbia (IMS VINS) in the EURADOS IC for the period 2010-2020 (excluding 2014) are presented. IMS VINS use thermoluminescent whole body dosemeters based on two TLD-100TM (Thermo Scientific™ Harshaw™, USA) detectors. The readouts are done on the Harshaw TLD™ Model 6600 Plus Automated Reader (Thermo Fisher Scientific, USA). The whole glow curve is used for dose estimation (all of 200 channels). The calibration of the dosimetric system is done twice a year in S-Cs (previously in S-Co) field at the secondary standard dosimetry laboratory (SSDL VINS), according to ISO 4037-3:2019. The IC had 40 different reference values of personal dose equivalent, Hp(10) in noted period ranging from 0.431 mSv to 501 mSv. There were 20, 16, 22, 22, 20 dosemeters irradiated in year 2010, 2012, 2016, 2018, 2020, respectively. The radiations were done in 12 different fields: N-60, S-Co, S-Cs, N-40, N-150, S-Cs+Sr90, S-Cs+N-40, W-110, S-Cs+W-250, W-60, S-Cs+W-80, and S-Cs+N-150. The relative response (R) range is from 0.23 to 2.26. Quantile values for R are: 0.23, 0.79, 0.90, 1.1, and 2.26, respectively for (0%, 25 %, 50 %, 75 % and 100 % of points). Mean and standard deviation of R are 0.97 and 0.30, respectively. The performance limits are established according to ISO 14146 trumpet-curve [1]. Due to trumpet-curve there were 6 outliers (2 in 2010, 4 in 2016). All of the outliers were for reference dose around 1 mSv and lower. One outlier from 2010 was irradiated in N-40 field and 30° of incident angle. The other outlier was irradiated in the S-Cs field, without any rotation, and thus should have had a satisfying response. The possible explanation is an insensitive TL detector. The outliers in 2016 were all for N-40 quality and ±60° angle. Thus, considering the low number of outliers (only one true outlier) and expected dosemeters faulty response for given irradiation parameters, we conclude that the IMS VINS dosimetry system had satisfactory behavior during IC from 2010-2020.X JUBILEE International Conference on Radiation in Various Fields of Research : RAD 2022 (Spring Edition) : book of abstracts; June 13-17, 2022; Herceg Novi, Montenegr

Harmonisation of dose measurement procedures using passive dosemeters: use of passive H*(10) dosimetry systems in Europe

Jedan od zadataka projekta 16ENV04 Preparedness jeispitivanje pasivnih dozimetrijskih sistema namenjenih za merenje operativne dozimetrijske veličine H*(10). Cilj ovog zadatka je evaluacija i harmonizacija procedura koji koriste laboratorije u Evropi a odnose se na merenje ambijentlnog ekvivalenta doze,a u vezi eventualne primene ovakvih doziemtrisjkih sistema u kontekstu dleovanja u vanrednom događaju.One of the outstanding tasks of the project 16ENV04 Preparedness, is to investigate the use of passive dosemeters aimed for measurement of operational quantityH*(10). The aim of this task is to develop a rationale to harmonize the procedures used by European measuring bodies and authorities, which provide services or fulfil tasks in radiation protection by using passive H*(10) area monitoring systems. Procedures used by European measuring bodies and services for environmental monitoring using passive area dosemeters are investigated, with a goal to investigate the applicability of passive dosimetry systems in the aftermath of a nuclear event.Proceedings: [http://vinar.vin.bg.ac.rs/handle/123456789/8681]XXX симпозијум ДЗЗСЦГ (Друштва за заштиту од зрачења Србије и Црне Горе), 2- 4. октобар 2019. године, Дивчибаре, Србиј

TLD-100 post-irradiation fading characteristics according to IEC 62387:2020 standard

The results of the post-irradiation fading of whole body dosemeters based on two TLD-100TM (Thermo Scientific™ Harshaw™, USA) detectors are presented. The dosemeters are regularly used by accredited individual monitoring service (IMS) at Vinca Institute of Nuclear Science (VINS), Belgrade, Serbia. The testing of post-irradiation fading was carried out according to International Electrotechnical Commission (IEC) 62387:2020 standard. The irradiations are done in S-Cs137 field at secondary standard dosimetry laboratory (SSDL) at VINS, according to International Organization for Standardization document ISO 4037-3:2019. The chosen reference personal dose equivalent value was 3 mSv. The research was carried out in the period from October 2020 to February 2021, and it lasted 128 days. The frequency of irradiations was approximately 7 days, while 3 periods between irradiations were longer than 10 days, due to COVID-19 pandemic. The irradiations were performed at different dates; thus, all dose readouts were done on the same day to prevent influence of reader’s instabilities. The irradiated dosemeters were stored at the same room where the average temperature was nearly 20°C. There were 14 groups with 6 dosemeters for irradiation and 2 dosemeters for natural background radiation level correction. The reader was Harshaw TLD™ Model 6600 Plus Automated Reader (Thermo Fisher Scientific, USA). The whole glow curve was used for dose estimation (all of 200 channels). The time as influence quantity was considered to be of type F, thus the range of relative response was limiting factor in the analysis. The results showed that the maximum measurement time tmax is 72 days for deep dose (Hp(10)) detector, and 85 days for shallow dose (Hp(0.07)) detector. Thus, the standard’s requirement is satisfied, as it is required minimum of 30 days. The relative response range for all of the 14 groups was from 0.82 to 1.14 and from 0.83 to 1.17, for deep and shallow dose, respectively. The research has limitation as the irradiations were organized aligned to COVID-19 working schedule. One of the consequences of this timetable is lack of 7 days’ time point, thus the values from 16 days’ time point was used as referential.IX International Conference on Radiation in Various Fields of Research : RAD 2021 : book of abstracts; June 14-18, 2021; Herceg Novi, Montenegr

Characteristics of local pulmonary response following intranasal application of Aspergillus fumigatus conidia

In this study, histopathology of local pulmonary response following intranasal inoculation of different doses of Aspergillus fumigatus conidia in laboratory rats was evaluated. Development of response was evaluated on days seven and twenty one, following conidia inoculation by cell infiltration and by presence of A. fumigatus conidia in homogenates of lung tissue. Total and differential peripheral blood leukocyte counts and state of leukocyte adhesion/aggregation were monitored to estimate the presence of systemic response in infected individuals. Mycological examination revealed the presence of conidia in lung tissue homogenates of infected animals, with high number of non-germinating spores on day twenty one, following the inoculation of lower conidia dose. Histopathological examination revealed the presence of lymphocytes perivascularly and in vascular lumen in the lungs. Presented data demonstrate pulmonary immune response following A. fumigatus conidia administration.Aspergillus fumigatus je oportunistička gljiva koja najčešće dovodi do pulmonarnih aspergiloza kod imunokompromitovanih organizama. U ovom radu su prikazani rezultati istraživanja izazivanja infekcije aspergilusom kod pacova. U cilju dobijanja podataka o prisustvu i karakteristikama lokalnog inflamatornog odgovora u plućima određen je diferencijalni sastav leukocita periferne krvi i testirana je njihova aktivnost, izvršeni su histopatološki pregled pluća i provera prisustva spora A. fumigatus u homogenatima pluća. Naši podaci su pokazali prisustvo lokalnog odgovora u plućima posle 7 dana dok podaci dobijeni posle 21 dan ne pokazuju značajne razlike u odnosu na kontrolnu grupu. Povećani broj neklijajućih spora u homogenatu pluća sedmog dana nakon inokulacije može da se objasni prisustvom limfocitnog infiltrata u plućima i aktivnošću limfocita in situ. Povećan broj klijajućih spora 21. dana nakon inokulacije može da bude posledica kapaciteta malog broja preostalih spora da klijaju.Projekat ministarstva br. 14303