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Open access

Jakub Osko and Natalia Golnik

Spectrometric measurements of radioisotope activity in the thyroid

The results of measurements of iodine 131I and technetium 99mTc uptake in human thyroid, performed with scintillation or semiconductor detectors can exhibit a considerable uncertainty due to the differences in the thyroid position in the patient's neck. Basic physical laws of radiation attenuation and scattering show that the final shape of the registered spectrum should depends on the thyroid position in the neck and on the thickness of the tissue between the thyroid and the detector. The use of the spectrometric measuring method is proposed in this work for determination of the iodine gathering effective depth. The performed studies showed that the measurements results can be used for improving the accuracy of the iodine 131I activity in thyroid measurements and for selection of the group of patients for whom the anatomical position of the thyroid or the spatial distribution of the iodine gathering is much different than the standard one, assumed during the calibration of the counters. The results of the measurements were in agreement with Monte-Carlo calculations of the detector response. The method was used in routine monitoring of occupationally exposed persons, using the thyroid counter. A group of six persons with measurable internal contamination was selected and the measurements were performed on consecutive days, so the results could be registered at decreasing iodine activities in the thyroid. Larger series of measurements were performed at Brodno Regional Hospital in Warsaw, for a group of 95 patients after diagnostic administration of iodine 131I.

Open access

Katarzyna Tyminska, Karol Jezierski and Jakub Osko

A virtual model of the patient's head for BNCT

The aim of the present work was creating a virtual phantom of a human head for BNCT, as a part of the BNCT programme project. This model is an amplification of the simple model described in earlier publications. It takes into account the major head organs as well as the scalp and skull. The chemical composition of all tissues was modelled according to the recommendations of the ICRP. The organs were parameterized using mathematical formulas based on the human head magnetic resonance images. The model was used for calculating the thermal neutron flux and the injuring (fast neutron, nitrogen and gamma) dose components for the head irradiated using the therapeutic neutron beam, whose parameters were obtained as the result of the modelling of the filter/moderator system for the BNCT therapeutic beam from the MARIA reactor.

Open access

Jakub Ośko and Katarzyna Tymińska

The aim of this work was to create a numerical model of scintillation detector and to check whether such detector can be used for the measurements of internal contamination in emergency conditions. The purpose of the measurements would be only detection of possible contamination, without identification of radioactive isotopes, and hence without estimation of effective dose. However, in emergency conditions, it is sufficient for the rapid selection of a group of contaminated persons, who should be subjected to careful inspection in the laboratory conditions. The calculations were performed for three detector positions relatively to the phantom. The distribution of dose rate was also calculated, in order to find the best geometry for dose rate measurements around human body. Another problem under consideration was the possible influence of radioactive contamination in the environment on the registration of the gamma spectrum emitted from the whole body phantom. Performed calculations showed that there is a possibility to measure internal contamination outside laboratory, even in contaminated area.

Open access

Krzysztof Pytel, Krzysztof Andrzejewski, Natalia Golnik and Jakub Osko

Concept of a BNCT line with in-pool fission converter at MARIA reactor in Swierk

BNCT facility in the Institute of Atomic Energy in Otwock-Swierk is under construction at the horizontal channel H2 of the research reactor MARIA. Measurements of the neutron energy spectrum performed at the front of the H2 experimental channel, have shown that flux of epithermal neutrons (above 10 keV) at the BNCT irradiation port was below 109 n cm-2 s-1 i.e. it was too low to be directly used for the BNCT treatment. Therefore, a fission converter will be placed between the reactor core and the periphery of the graphite reflector of MARIA reactor. The uranium converter will be powered by the densely packed EK-10 fuel elements with 10% enrichment. Preliminary calculations have shown that the total neutron flux in the converter will be about 1013 n cm-2 s-1 and flux of epithermal neutrons at the entrance to the filter/moderator of the beam will be about 2·1013 n cm-2 s-1.

Open access

Ciszewska Katarzyna, Dymecka Malgorzata, Pliszczynski Tomasz and Osko Jakub

Improvement of the quality of effective dose estimation by interlaboratory comparisons

Radiation Protection Measurements Laboratory (RPLM) of the Institute of Atomic Energy POLATOM determines radionuclides in human urine to estimate the effective dose. Being an accredited laboratory, RPLM participated in interlaboratory comparisons in order to assure the quality of services concerning monitoring of internal contamination. The purpose of the study was to examine the effect of interlaboratory comparisons on the accuracy of the provided measurements. The results regarding tritium (3H) and strontium (90Sr) determination, obtained within the radiotoxicological intercomparison exercises, organized by PROCORAD, in 2005-2010, were analyzed and the methods used by the laboratory were verified and improved.

Open access

Maciej Szuchta and Jakub Ośko

Abstract

The aim of this study was to develop a numerical model of spectrometric thyroid counter, which is used for the measurements of internal contamination by in vivo method. The modeled detector is used for a routine internal exposure monitoring procedure in the Radiation Protection Measurements Laboratory of National Centre for Nuclear Research (NCBJ). This procedure may also be used for monitoring of occupationally exposed nuclear medicine personnel. The developed model was prepared using Monte Carlo code FLUKA 2011 ver. 2b.6 Apr-14 and FLAIR ver. 1.2-5 interface. It contains a scintillation NaI(Tl) detector, the collimator and the thyroid water phantom with a reference source of iodine 131I. The geometry of the model was designed and a gamma energy spectrum of iodine 131I deposited in the detector was calculated.

Open access

Jakub Ośko, Natalia Golnik, Tomasz Pliszczyński, Renata Sosnowiec, Marianna Umaniec and Mieczysław Zielczyński

Iodine activity in thyroid of female patient was measured with different radiation meters in order to estimate a possibility to use them in case of radiation accident. Two series of measurements were performed - first after diagnostic and second after therapeutic administration of iodine to the patient. The isotope activities were higher than those registered during routine radiation monitoring and similar to the activities which could be registered after radiation accident. The studies showed that simple dose rate meters may serve for identification and selection of contaminated persons which should be later subjected to the measurements with especially dedicated equipment. The initial measurements can be performed outside laboratory.

Open access

Tomasz Pliszczyński, Katarzyna Ciszewska, Małgorzata Dymecka, Jakub Ośko and Zbigniew Haratym

Fission products of 235U or isotopes from activation may appear in technological waters at normal operation of a research reactor. Therefore, reactor cooling water may contain a number of beta radioactive isotopes including yttrium and strontium isotopes, which can pose potential hazard to reactor personnel. In order to asses internal exposure urinalysis is carried out. This work presents the method of sample preparation and measurement used by Radiation Protection Measurements Laboratory (RPLM) of the National Centre for Nuclear Research (NCNR). Method of various isotopes of yttrium and Sr-90 activity calculation is also shown. Determination of these isotopes activities in urine sample allows estimating the effective doses

Open access

Tomasz Pliszczyński, Jakub Ośko, Katarzyna Ciszewska, Zbigniew Haratym, Marianna Umaniec and Renata Sosnowiec

Ocena narażenia wewnętrznego za pomocą licznika promieniowania ciała człowieka

Proces oceny narażenia wewnętrznego na skażenia substancjami promieniotwórczymi jest skomplikowany i towarzyszy mu wiele czynników, które są źródłem niepewności szacowania obciążającej dawki efektywnej. W niniejszym artykule przedstawiono sposób właściwego postępowania podczas szacowania obciążającej dawki efektywnej za pomocą Licznika Promieniowania Ciała Człowieka.

Open access

Katarzyna Rzemek, Andrzej Czerwiński, Małgorzata Dymecka, Jakub Ośko, Tomasz Pliszczyński and Zbigniew Haratym

Abstract

The studies aimed at determining low activities of alpha radioactive elements are widely recognized as essential for the human health, because of their high radiotoxicity in case of internal contamination. Some groups of workers of nuclear facility at Otwock are potentially exposed to contamination with plutonium isotopes. For this reason, the method for determination of plutonium isotopes has been introduced and validated in Radiation Protection Measurements Laboratory (LPD) of the National Centre for Nuclear Research (NCBJ). In this method the plutonium is isolated from a sample by coprecipitation with phosphates and separated on a AG 1-X2 Resin. After electrodeposition, the sample is measured by alpha spectrometry. Validation was performed in order to assess parameters such as: selectivity, accuracy (trueness and precision) and linearity of the method. The results of plutonium determination in urine samples of persons potentially exposed to internal contamination are presented in this work.