Performance testing of active electronic dosimeters for the purpose of harmonization of operational dosimetric quantities measurements in the field of radiation protection

Оперативне дозиметријске величине представљају директно мерљиве физичке величине које се на основу калибрације дозиметара користе за процену физичких величина у области зашитите од зрачења, еквивалентне и ефективне дозе. Активни електронски дозиметри за индивидуални и амбијентални мониторинг јонизујућег зрачења се у све већој мери користе поред конвенционалних пасивних дозиметријских система. Стога је од значаја спровести адекватнa испитивања типа дозиметара у пољима фотонског јонизујућег зрачења различитих енергија и упадних углова. Испитивање под наведеним условима пружају адекватну процену дозиметријских карактеристика дозиметара у реалним пољима зрачења која су полиенергетска и мултидирекциона. Испитивање тачности, линеарности, енергетске и угаоне зависности одзива дозиметара је извршено на десет модела активних електронских личних дозиметара различитих механизама детекције јонизујућег зрачења (гасних, полупроводничких и сцинтилационих детектора, различитих произвођача), као и амбијенталног дозиметра који садржи гасни детектор под високим радним напоном. Испитивање је извршено за некомпензовану цилиндричну Гајгер-Милерову цев, као и за варијанте енергетске компензације инхерентних својстава бројачког детектора, при чему је целокупна активна запремина прекривена компензационим материјалом различите дебљине, или је у компензациони материјал уведен ваздушни процеп варијабилне ширине. Вредности апсолутног и релативног одзива дозиметара су упоређене са међународним стандардима за испитивање активних електронских дозиметара за лични мониторинг и за амбијентални мониторинг. Коришћен је широк опсег утицајних величина енергије фотона (од 33 keV до 1,33 MeV), угла инциденције фотона (од 0° до 80° за личне дозиметре позициониране на водени блок-фантом који верно представља људски торзо, и од 0° до 90° уз вредности од -45° и 180° ради испитивања изотропности одзива амбијенталних дозиметара). Испитивањем активних електронских дозиметара је утврђено да велики број дозиметара за индивидуални мониторинг има вредности дозиметријских карактеристика у складу са међународним стандардом у области личне дозиметрије, док је за амбијентални дозиметар на бази Гајгер-Милерове цеви одређена оптимална енергетска компензација која резултира задовољавајућим вредностима дозиметријских карактеристика при широком опсегу вредности утицајних величина. У сврху амбијенталног мониторинга животне средине је извршена карактеризација кдамијум-цинк телуридног спектрометра тако да се може користити као спектро-дозиметар, односно за одређивање јачине амбијенталног дозног еквивалента конверзијом из снимљених спектара висине импулса.Operational dosimetric quantities represent directly measurable physical quantities that can be used for conservative estimation of radiation protection quantities, equivalent and effective dose. Active electronic dosimeters for individual and ambient monitoring of ionising radiation are being increasingly used alongside conventionally used passive dosimetric systems. It is crucial to execute appropriate type testing methods of dosemeters in various photon radiation fields of various energies and angles of incidence. Testing under mentioned conditions is a legitimate estimation of dosimetric properties in realistic ionising radiation fields, which are by nature polyenergetic and multidirectional. Testing of dosemeter accuracy, linearity, energy and angular dependence of the response has been performed on ten different personal dosemeter models (of different manufacturers and different detection mechanisms, employing gaseous, semiconductor and scintillation detectors), and on an ambient monitoring radiation dosemeter which contains a gas detector under high applied voltage. The testing has been executed for uncompensated cylindrical Geiger-Müller tube, and for different energy compensation solutions, employing complete covering of active volume of the tube with the compensation material of various thicknesses, and by introducing an air-gap of varying width in the compensation material. The values of absolute and relative response have been evaluated by comparing with the acceptability criteria set by international standards for active electronic dosemeter testing, both for dosemeters used in individual monitoring and ambient monitoring. A wide range of influence quantities’ values has been used, including photon energy (from 33 keV up to 1,33 MeV), angle of incidence of primary photon beam (from 0° to 80° for personal dosemeters which were positioned on a reference water slab phantom which approximates human torso, and from 0° up to 90° with additional values of -45° and 180° used to test response symmetry for ambient dosemeters). The conclusion derived from the testing of active electronic dosemeters is that a large number of tested personal dosemeters performs satisfactorily in accordance with personal dosimetry international standard for type testing, while for the Geiger-Müller tube based ambient dosemeter optimal energy compensation has been detected, resulting in satisfying results of tested dosimetric properties in a wide range of influence quantities’ values. For the purpose of environmental monitoring characterization of a cadmium-zinc telluride spectrometer for its use as a spectro-dosemeter has been performed, in order to determine the ambient dose equivalent rate from the recorded pulse-height spectra

Establishing W/Al mammography radiation qualities in Secondary Standard Dosimetry Laboratory

In mammography clinical practice, various radiation fields are used, produced using different X-ray tube anode and filtration setups. It is important to calibrate diagnostic dosimeters in different radiation qualities as these dosimeters are used for quality control tests and most dosimeters have significant dependence of response on radiation spectra. TRS 457 Code of Practice [1] is an IAEA document which recommends calibration of diagnostic dosimeters in reference radiation fields established according to IEC 61267:2005 international standard [2], which considers the Mo/Mo anode-filter combination (abbreviated as the RQR-M series). Other, non-standard beam qualities are also used for calibration, such as the beams with W/Al anode-filter combination, used by Vinca Institute Secondary Standard Dosimetry Laboratory. Traceability is established to IAEA Dosimetry Laboratory, and radiation qualities are established by adding 0.5 mm Al additional filtration, following the IAEA procedure [3]. Mammography radiation qualities can be validated by determining the half-value layer (HVL) of the radiation beam. To determine HVL we measured incident air kerma at 1 m distance using a 1 cm3 plane parallel ionization chamber, by successively adding Al attenuators of different thickness. The Al attenuators have been placed at 0.5 m distance, equidistantly from the radiation source and the ionization chamber. HVL was obtained using a linear regression for the additional filtration values near the expected HVL value. Calculated HVL was 0.326 mm Al, 0.367 mm Al, 0.395 mm Al, 0.456 mm Al for tube voltages 25 kV, 28 kV, 30 kV and 35 kV, respectively. The results were compared with the values given by IAEA SSDL [3] (deviation for all qualities was less than 5%) and PTB Primary Standard Dosimetry Laboratory (PSDL) [4]. Radiation qualities established in this manner allow proper calibration and traceability of diagnostic dosimeters in W/Al radiation qualities to be used for routine QC tests in mammography.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

Determination of uniformity and field size of reference X-ray beams

Cilj ovog rada je da se ispita uniformnost i veličina referentnog polja generisanog pomoću generatora X-zračenja. U tu svrhu je koriššena jonizaciona komora male zapremine tako što su mapirane jačine doze. Na osnovu merenja, određen je korekcioni faktor za neuniformnost polja zračenja. Rezultati prikazani u ovom radu se odnose na polje kolimisano pomoću aperture prečnika 4,2 cm i generisano pomoću generatora X-zračenja konstantnog napona i struje. Ispitivanje je izvršeno u kvalitetu zračenja koji se koristi u dijagnostičkoj radiologiji, ali je ova procedura takođe primenjiva i na kvalitete koji se koriste za etaloniranje uređaja za zaštitu od zračenja definisane u novoj verziji ISO 4037 iz 2019. godine.The aim of this paper is to study the uniformity and the size of a reference radiation field produced by an x-ray generator. This work uses a technique to map dose distribution and measure dose rates with a small-volume spherical ionization chamber in order to determine the correction factor for non uniformity of the radiation field. Results shown in this paper are profile measurementsperformed in radiation beam collimated by a 4.2 cm diameter aperture, generated by calibration x-ray equipment of constant voltage and current. Thestudy was conducted in a diagnostic radiology radiation quality, but this procedure is also applicable to the new revised version of ISO 4037 standard from 2019 which specifies protection level reference radiation qualities.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

Vendor‐independent skin dose mapping application for interventional radiology and cardiology

Purpose: The purpose of this paper is to present and validate an originally developed application SkinCare used for skin dose mapping in interventional procedures, which are associated with relatively high radiation doses to the patient’s skin and possible skin reactions. Methods: SkinCare is an application tool for generating skin dose maps following interventional radiology and cardiology procedures using the realistic 3D patient models. Skin dose is calculated using data from Digital Imaging and Communications in Medicine (DICOM) Radiation Dose Structured Reports (RDSRs). SkinCare validation was performed by using the data from the Siemens Artis Zee Biplane fluoroscopy system and conducting “Acceptance and quality control protocols for skin dose calculating software solutions in interventional cardiology” developed and tested in the frame of the VERIDIC project. XR-RV3 Gafchromic films were used as dosimeters to compare peak skin doses (PSDs) and dose maps obtained through measurements and calculations. DICOM RDSRs from four fluoroscopy systems of different vendors (Canon, GE, Philips, and Siemens) were used for the development of the SkinCare and for the comparison of skin dose maps generated using SkinCare to skin dose maps generated by different commercial software tools (Dose Tracking System (DTS) from Canon, RadimetricsTM from Bayer and RDM from MEDSQUARE). The same RDSRs generated during a cardiology clinical procedure (percutaneous coronary intervention—PCI) were used for comparison. Results: Validation performed using VERIDIC's protocols for skin dose calculation software showed that PSD calculated by SkinCare is within 17% and 16% accuracy compared to measurements using XR-RV3 Gafchromic films for fundamental irradiation setups and simplified clinical procedures, respectively. Good visual agreement between dose maps generated by SkinCare and DTS, RadimetricsTM and RDM was obtained. Conclusions: SkinCare is proved to be very convenient solution that can be used for monitoring delivered dose following interventional procedures. © 2021 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine

EURAMET i DOSEtrace project and supplementary comparison

Tačna i sledljiva merenja operativnih veličina su neophodna za adekvatnu zaštitu od zračenja. Nacionalni metrološki instituti i Imenovani instituti su zaduženi za diseminaciju SI jedinice Sivert i za etaloniranje korisničke opreme. Ipak, u velikom broju Evropskih zemalja, mogušnosti etaloniranjaza operativne veličine su nedovoljno razvijene ili nepostoješe. Glavni cilj DOSEtrace projekta je unapređenje ovih mogućnosti, kao i smanjenje proširene merne nesigurnosti učesnika projekta ispod 5 % (k = 2). U okviru projekta še biti sprovedena Dodatna interkomparacija kalibracionih faktora za ambijentalni dozni ekvivalent. Ova interkomparacija še pomoši učesnicima projekta da validiraju merne mogušnosti razvijene pre i tokom projekta, a takođe će pomoći novim institutima da steknu međunarodno priznanje. U okviru intercomparacije, biše pokriveni kvaliteti zračenja radionuklida, kao i x-zračenja.Accurate and traceable measurements of operational quantities are required for adequate radiation protection. National Measurement Institutes (NMI) and Designated Institutes (DI) are responsible for disseminating the SI unit sievert and for calibrating user equipment. However, in many emerging European countries, calibration and measurement capabilities for operational quantities are limited or nonexistent. The main objective of DOSEtrace project is to improve these capabilities and for the participants to achieve the expanded measurement uncertainty of less than5% (k = 2). Within the project, a Supplementary comparison of calibration factors in terms of ambient dose equivalent will be conducted. This comparison will help to validate the capabilities that the partners developed during and before the project and will help emerging institutes gain international recognition. The comparison will cover both radionuclide and x-ray radiation qualities according to ISO 4037-1.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

The validity of the exponential law of attenuation for the beam of gamma radiation in depending on the thickness and type of material of the absorber

Pri proračunu i projektovanju strulturalne zaštite od zračenja potrebno je na osnovu poznavanja interakcija koje karakterišu prolaz različitih vrsta zračenja kroz materijal izvući zaključke o prolasku čestica ili kvanata zračenja kroz apsorbere različitih debljina, geometrija, izrađene od različitih materijala. U ovom radu ispituje se važenje eksponencijalnog zakona atenuacije snopa gama zračenja u zavisnosti od debljine i vrste materijala apsorbera. Kao apsorberi su korišćeni aluminijum i olovo. Eksperimentalni podaci su pokazali opseg vrednosti površinske gustine i debljine apsorbera u kome važi eksponencijalni zakon slabljenja inteziteta gama zračenja u geometriji uzanog snopa, kao i opseg vrednosti površinske gustine i debljine apsorbera u kom je neophodno uračunati faktor nagomilavanja.The calculation and design of radiation protection shielding should be based on the interactions that characterize the passage of various types of radiation through the material to draw conclusions about the passage of particles or quanta of radiation through absorbers of different thickness, geometry, made of different materials. This paper examines the validity of the exponential law of attenuation for a beam of gamma radiation, depending on the thickness and type of material of the absorber. Aluminium and lead were used as absorbers. Experimental data showed a range of values of the surface density and the thickness of the absorber in which the exponential law of attenuation of gamma rays can be applied in the narrow-beam geometry, as well as the range of values of the surface density and the thickness of the absorber where it is necessary to include the build-up factor

Comparison of experimental and simulated responses of TL and OSL dosimeters in poly-energetic and multi-directional photon radiation fields

The aim of this paper is to examine the energy and angular responses of thermoluminescent (LiF:Mg,Ti and LiF:Mg,Cu,P) and optically stimulated luminescent (Al2O3:C) dosimeters with experimental measurements and Monte Carlo simulations. Nine radiation qualities, with mean energies ranging from 33 keV to 1.25 MeV, and five angles of incidence, between 0° and 80°, were used to conduct this analysis. The IEC 62387:2020 international radiation protection standard was used as the dosimeter response measure of quality. The experimental and simulated data exhibit that the dosimeter responses meet the standard's criteria, with certain exceptions on lower energies

Evaluation of diagnostic radiology detector performance in reference mammography radiation fields

Recommendations on diagnostic radiology calibrations are defined by the IEC and IAEA documents for molybdenum anode target material and molybdenum primary beam filtration (abbreviated as the RQR-M series). Calibration of diagnostic radiology dosimeters (ionization chambers and X-ray multimeters) can also be performed for other anode/filter combinations, including the tungsten anode / aluminium filtration setup. Performance of dosimeters can significantly vary in radiation fields defined by different anode materials and primary beam filtrations, where different spectra and first half-value layers are obtained for the same nominal X-ray tube voltages. Therefore it is important to calibrate or test dosimeters for the range of radiation qualities or conditions in which they will be used. Performance of two such detectors was evaluated.XXXII симпозијум ДЗЗСЦГ (Друштва за заштиту од зрачења Србије и Црне Горе), 4-6. октобар 2023. годин

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

Determination of uniformity and field size of reference X-ray beams

Cilj ovog rada je da se ispita uniformnost i veličina referentnog polja generisanog pomoću generatora X-zračenja. U tu svrhu je koriššena jonizaciona komora male zapremine tako što su mapirane jačine doze. Na osnovu merenja, određen je korekcioni faktor za neuniformnost polja zračenja. Rezultati prikazani u ovom radu se odnose na polje kolimisano pomoću aperture prečnika 4,2 cm i generisano pomoću generatora X-zračenja konstantnog napona i struje. Ispitivanje je izvršeno u kvalitetu zračenja koji se koristi u dijagnostičkoj radiologiji, ali je ova procedura takođe primenjiva i na kvalitete koji se koriste za etaloniranje uređaja za zaštitu od zračenja definisane u novoj verziji ISO 4037 iz 2019. godine.The aim of this paper is to study the uniformity and the size of a reference radiation field produced by an x-ray generator. This work uses a technique to map dose distribution and measure dose rates with a small-volume spherical ionization chamber in order to determine the correction factor for non uniformity of the radiation field. Results shown in this paper are profile measurementsperformed in radiation beam collimated by a 4.2 cm diameter aperture, generated by calibration x-ray equipment of constant voltage and current. Thestudy was conducted in a diagnostic radiology radiation quality, but this procedure is also applicable to the new revised version of ISO 4037 standard from 2019 which specifies protection level reference radiation qualities.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