Usage of virtual voxel with CT data in particles trajectory modeling by Monte Carlo techniques

U simulaciji prolaza čestica tehnikama Monte Karlo aktuelni geometrijski moduli upotrebljavaju površine prvog i drugog reda (FOTELP, PENELOPE, SHIELD, GEANT), a nekad i četvrtog reda(MCNP5), da opišu složene geometrijske forme.. Sve veća primena tehnika Monte Karlo u medicini oslanja se na vokselizovane geometrijske forme koje se dobijaju vokselizaciom fantoma ili iz CT podataka. Ogroman broj tela (voxela) u tom slučaju otežava primenu konstruktivne geometrije. Eefikasniji pristup tom problemu zasniva se na primeni virtuelnog voksela.Ovde se saopštavaju rezultati upotrebe virtuelnog voksela na anatomiju tela i organa upotrebom CT podataka.Geometry modules in particle transport simulation codes with Monte Carlo techniques use surfaces of first and second order, sometimes even a fourth order surfaces, to be able to describe complex geometrical shapes. Constructive quadric geometry dominates in all leading software packages. Increasing application of Monte Carlo techniques in medicine is associated with voxelized geometry forms. Huge number of bodies present in this case makes the use of constructive geometry more difficult. The paper describes an efficient approach to this problem by virtual voxel application, where optical distance to the boundary is obtained, and 3D voxel indices give information about the materials present in voxel.XXIV Simpozijum Društva za zaštitu od zračenja Srbije i Crne Gore, Zlatibor, 3-5. oktobar 2007

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

Radiology staff dose assessment in primary health centers

Cilj ovog rada je procena efektivnih doza radiološkog osoblja profesionalno izloženih jonizujućem zračenju u domovima zdravlja u Srbiji. Za procenu doza su primenjene dve metode: (1) merenje ambijentalnog ekvivalenta doze, H* (10), korišćenjem jonizacione komore; i (2) merenje ličnog ekvivalenta doze, Hp(10), korišćenjem termoluminescentnih dozimetara (TLD). Doze su procenjene za radiologe iz devet domova zdravlja koji rade iz kontrolisane zone zračenja i radiologe iz sedam domova zdravlja koji rade iz nadgledane zone zračenja. Godišnje doze su date za radiologe i radiološke tehničare za period od pet uzastopnih godina (2011-2015). Prosečna procenjena godišnja doza ne prelazi 12 mSv, na osnovu merenja H* (10), dok je 1,65 mSv maksimalna godišnja doza izmerena TLD metodom. Dobijeni rezultati pokazuju da doze osoblja ne prelaze zakonski predviđenu granicu godišnje doze od 20 mSv.The aim of this study is to estimate the effective doses to workers occupationally exposed to ionizing radiation in small health centers in Serbia. To assess doses two methods were applied: (1) the measurement of the ambient equivalent dose, H*(10) using ionization chambers routinely utilized during workplace monitoring; and (2) the measurement of the personal equivalent dose, Hp(10), using thermoluminescent dosemeters routinely utilized during individual monitoring. Doses were estimated for radiologist working from controlled and supervised area. Annual doses are given for for a period of five consecutive years (2011-2015). The average annual dose does not exceed 12 mSv assessed by the workplace monitoring method, or 1.65 mSv measured by the individual monitoring method. The results show that estimated doses are well below annual dose limits of 20 mSv for the occupational exposure

Radiology staff dose assessment in primary health centers

Cilj ovog rada je procena efektivnih doza radiološkog osoblja profesionalno izloženih jonizujućem zračenju u domovima zdravlja u Srbiji. Za procenu doza su primenjene dve metode: (1) merenje ambijentalnog ekvivalenta doze, H* (10), korišćenjem jonizacione komore; i (2) merenje ličnog ekvivalenta doze, Hp(10), korišćenjem termoluminescentnih dozimetara (TLD). Doze su procenjene za radiologe iz devet domova zdravlja koji rade iz kontrolisane zone zračenja i radiologe iz sedam domova zdravlja koji rade iz nadgledane zone zračenja. Godišnje doze su date za radiologe i radiološke tehničare za period od pet uzastopnih godina (2011-2015). Prosečna procenjena godišnja doza ne prelazi 12 mSv, na osnovu merenja H* (10), dok je 1,65 mSv maksimalna godišnja doza izmerena TLD metodom. Dobijeni rezultati pokazuju da doze osoblja ne prelaze zakonski predviđenu granicu godišnje doze od 20 mSv.The aim of this study is to estimate the effective doses to workers occupationally exposed to ionizing radiation in small health centers in Serbia. To assess doses two methods were applied: (1) the measurement of the ambient equivalent dose, H*(10) using ionization chambers routinely utilized during workplace monitoring; and (2) the measurement of the personal equivalent dose, Hp(10), using thermoluminescent dosemeters routinely utilized during individual monitoring. Doses were estimated for radiologist working from controlled and supervised area. Annual doses are given for for a period of five consecutive years (2011-2015). The average annual dose does not exceed 12 mSv assessed by the workplace monitoring method, or 1.65 mSv measured by the individual monitoring method. The results show that estimated doses are well below annual dose limits of 20 mSv for the occupational exposure

The measurement of ambient dose equivalent by passive dosimeters method during CBRN exercise

Za potrebe obuke lica za delovanje u slučaju hemijskih, bioloških, radioloških i nuklearnih akcidenata (HBRN) uspostavljena je platforma u okviru Instituta za nuklearne nauke Vinča (INNV). Na samoj platformi se između ostalih izvode praktična uvežbavanja: lociranja radioaktivnog izvora, obezbeđivanja izvora i različitih scenarija dekontaminacije. Jedna od nadležnosti Laboratorije za zaštitu od zračenja i zaštitu životne sredine (Zaštita) je da primeni odgvarajuće mere radi kontrolisanog izlaganja jonizujućem zračenju pojedinaca na platformi kao i radnika INNV. U ovom radu su prikazani rezultati merenja ambijentalnog ekvivalenta doze, H*(10) pomoću termoluminiscentnih dozimetara (TLD) koji su postavljeni u cilju monitoringa okoline tokom HBRN vežbe koja je izvedena u aprilu 2017. Merenja su vršena postavljanjem TLD na 22 lokacije na samoj platformi i van nje u trajanju od 14 dana. Izmerena srednja vrednost H*(10) iznosi 34 µSv za posmatrani period što pokazuje da nije došlo do značajnog povećanja ambijentalne ekvivalentne doze u odnosu na osnovni nivo prirodnog zračenja.For the purpose of professional responder training in the case of chemical, biological, radiological and nuclear accidents (CBRN), a training platform was established within the Vinca Institute of Nuclear Sciences (INNV). On the platform, among other things, practical exercises are carried out such as: locating radioactive sources, securing sources and various decontamination scenarios. One of the responsibilities of the Department of Radiation and Environmental Protection (Zastita) is to apply specific measures for the controlled exposure to ionizing radiation of individuals on the platform as well as of INNV workers. This paper presents the ambient dose equivalent H*(10), measured using thermoluminescent dosimeters (TLDs) that were set up to monitor the environment during the CBRN exercise in April 2017. The measurements were made by placing the TLD at 22 locations on the platform itself, and out of it for 14 days. The mean H*(10) is 33 µSv for the observed period, which shows that there was no significant increase in the ambient dose relative to the background level.Зборник радова : XXIX симпозијум ДЗЗСЦГ : Сребрно језеро, 27-29. септембар 2017. годин

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

Eye lens monitoring in interventional cardiology and radiology

Sledeći rezultate epidemioloških studija o efektu jonizujućih zračenja na očno stočivo, Međunarodna komisija za zaštitu od zračenja revidirala je granicu izlaganja za očno sočivo, imajući u vidu da u slučaju dugotrajnog izlaganja malim dozama i malim jačinama doza na radnom mestu, katarakta može nastati na nivou doze daleko manjim od ranije utvrđenog praga. Ovakve situacije su tipične za profesionalna izlaganja u interventnoj kardiologiji i radiologiji. Cilj ovog rada je prikaz metodologije za donošenje odluke o potrebi za individualnim monitringom za očno sočivo i prikaz rezultata pilot monitoringa u interventnoj kardiologiji pomoću namenskih dozimetara za očno sočivo kalibrisanim u dozimetrijskoj veličini lični dozni ekvivalent Hp(3).Following recent epidemiological evidences on effects of ionizing radiation to the eye lens, International Commission on Radiological Protection has re-evaluated dose limit to the lens of the eye, owing that protracted exposure to the relatively small doses and dose rates may lead to the cataract at dose levels much lower than previously set dose thresholds. Such satiations are typical for occupational exposure in interventional cardiology and radiology. Occupational exposure from interventional x-ray procedures is an area in which increased eye lens exposure may occur. Accurate dosimetry is an important element to investigate the correlation of observed radiation effects with radiation dose, to verify the compliance with regulatory dose limits, and to optimize radiation protection practice. The papers presents the overview of practical methods for eye lens doses assessment as well as typical occupational eye lens dose levels in interventional procedures in cardiology and radiology. In addition, a methodology to assist decision making about need for specific eye lens individual monitoring using a dedicated passive dosimeters calibrated in terms of Hp(3) is presented in this paper

Environmental Impact Assessment of the Nuclear Reactor in Vinca, Based on the Data on Emission of Radioactivity from the Literature - a Modeling Approach

Research activities of Vinca Institite have been based on two heavy water research reactors: a 10 MW one, RA, and zero power, RB. Reactor RA was operational from 1962 to 1982. In 2010, spent fuel has been sent to the country of origin, and the reactor now is in decommissioning. During the operational phase of the reactor there were no recorded accidental releases into the environment, only operational ones. Results of the environmental impact assessment of the assumed emission of radionuclides from the ventilation of nuclear reactor RA in Vinca to the atmospheric boundary layer are presented in this paper. Evaluation was done by using the Gaussian straight-line diffusion model and taking into account characteristics of the reactor ventilation system, the assumed emission release of radioactivity (from the literature), site-specific meteorological data for six-year period and local topography around nuclear reactor, and corresponding dose factors for inventory of radionuclides. Based on the described approach, and assuming that the range of appropriate meteorological data for six year period for the application of described mathematical model is enough for this kind of analysis, it can be concluded that the nuclear reactor RA, in the course of its work from 1962 to 1982, had no influence on the surrounding environment through the air above regulatory limits

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