| 1. |
- Isaksson, M., et al.
(författare)
-
Determination of the retention of 47Ca by whole-body counting
- 2000
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Ingår i: Applied Radiation and Isotopes. - 0969-8043 .- 1872-9800. ; 52:6, s. 1441-1450
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Tidskriftsartikel (refereegranskat)abstract
- Retention of intravenously or orally administered 47Ca in the human body are described by a two-parameter function. It is then sufficient to make only a few whole-body measurements to determine the retention function, avoiding faeces sampling and stool markers. Seven days after intake the non-absorbed calcium was excreted and the model agreed with the measured relative retention. Absorption of calcium could then, in some cases (e.g. comparative studies), be described by relative retention at the 7th day after intake. Copyright (C) 2000 Elsevier Science Ltd.
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| 2. |
- Jacobsson, S, et al.
(författare)
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A tomographic method for experimental verification of the integrity of spent nuclear fuel
- 2000
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Ingår i: Applied Radiation and Isotopes. - 0969-8043 .- 1872-9800. ; 53:4-5, s. 681-689
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Tidskriftsartikel (refereegranskat)abstract
- A tomographic method for verification of the integrity of spent nuclear fuel assemblies has been developed. The gamma radiation field emanating from emitted radiation from within the assembly is recorded and utilised for reconstructing the internal source
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| 3. |
- Lubberink, Mark, et al.
(författare)
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Quantification aspects of patient studies with 52Fe in positron emission tomography
- 1999
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Ingår i: Applied Radiation and Isotopes. - 0969-8043 .- 1872-9800. ; 51:6, s. 707-715
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Tidskriftsartikel (refereegranskat)abstract
- Quantification accuracy in positron emission tomography (PET) using non-pure positron emitters, such as 52Fe, may be influenced by gamma radiation emitted in the decay of these isotopes. High-energy positrons, emitted in the decay of the 52Fe-daughter 52mMn, also affect the quantification accuracy. A specific problem of the 52Fe/52mMn decay chain in vivo is that the kinetics of iron and manganese are different, and that PET cannot discriminate between the two nuclides. The effect of the decay properties of 52Fe/52mMn on the performance of PET was investigated using phantoms. Minor degradation in PET performance was found for 52Fe/52mMn compared to the pure low-energy positron emitter 18F. A method is presented to obtain a correction factor for the 52mMn radioactivity in blood. A model for correction of 52mMn-radioactivity in organs, based on existing data on manganese kinetics, is given. The presented corrections are discussed and illustrated in a patient study.
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| 4. |
- Nilsson, Jonas, 1969-, et al.
(författare)
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The effects of UV-irradiation on the ESR-dosimetry of tooth enamel
- 2001
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Ingår i: Applied Radiation and Isotopes. - 0969-8043 .- 1872-9800. ; 54:1, s. 131-139
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Tidskriftsartikel (refereegranskat)abstract
- Tooth enamel has been shown to be an excellent dosimeter material for retrospective dosimetry. A complication is that it is sensitive to ultraviolet light (UV), creating a signal that interferes with the dosimetric signal. Irradiation of tooth enamel by UV-light induces a mixture of stable and unstable free radicals. The unstable radicals disappear in about three weeks. Stable radicals are created both at the dosimetric peak and at the same g-value as the native peak. The stable peak coinciding with the native peak shows saturation behavior both for UVA/B- and UVC-light. The signal intensity from the sun is roughly estimated to induce a signal comparable to 15 mGy/h from 60 kV X-rays. The blue lamps used by dentists when hardening plastic repairs contain a narrow tail in the UVA/B-region, and it is shown here that these lamps also contribute to the stable peak coincident with the native peak. The contribution to the dosimetry peak, though negligible, at least for the irradiation times is used in this work. Most of the problems with UVA/B-induced signal contributions can probably be avoided by not using front teeth and teeth close to plastic repairs. (C) 2000 Elsevier Science Ltd.Tooth enamel has been shown to be an excellent dosimeter material for retrospective dosimetry. A complication is that it is sensitive to ultraviolet light (UV), creating a signal that interferes with the dosimetric signal. Irradiation of tooth enamel by UV-light induces a mixture of stable and unstable free radicals. The unstable radicals disappear in about three weeks. Stable radicals are created both at the dosimetric peak and at the same g-value as the native peak. The stable peak coinciding with the native peak shows saturation behavior both for UVA/B- and UVC-light. The signal intensity from the sun is roughly estimated to induce a signal comparable to 15 mGy/h from 60 kV X-rays. The blue lamps used by dentists when hardening plastic repairs contain a narrow tail in the UVA/B-region, and it is shown here that these lamps also contribute to the stable peak coincident with the native peak. The contribution to the dosimetry peak, though negligible, at least for the irradiation times is used in this work. Most of the problems with UVA/B-induced signal contributions can probably be avoided by not using front teeth and teeth close to plastic repairs.
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| 5. |
- Olsson, Sara, 1970-, et al.
(författare)
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Ammonium tartrate as an ESR dosimeter material
- 1999
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Ingår i: Applied Radiation and Isotopes. - 0969-8043 .- 1872-9800. ; 50:5, s. 955-965
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Tidskriftsartikel (refereegranskat)abstract
- This study is one step in the search for an ESR dosimeter material with a higher signal intensity than the commonly used l-α-alanine, to be useful in the clinical dose range (approximately 0.1–20 Gy). The substance ammonium tartrate was found and investigated regarding signal intensity, radical stability, dose response and dose resolution. The ESR signal intensity of ammonium tartrate was shown to be more than twice the intensity of the alanine signal. The data indicate that an unstable radiation induced radical contributes to the ESR signal initially; after a couple of hours it has converted to a secondary radical which has a decay slow enough to be considered stable during the first two weeks after irradiation. Ammonium tartrate has a linear dose response in the investigated range of 0.5–4000 Gy and a dose resolution of 0.1 Gy at the 0.5 Gy level where, as a comparison, the corresponding value for alanine is 0.3 Gy. We thus find the substance suitable for clinical dosimetry.
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| 6. |
- Olsson, Sara, et al.
(författare)
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Dose response and fading characteristics of an Alanine-Agarose gel
- 1996
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Ingår i: Applied Radiation and Isotopes. - 0969-8043 .- 1872-9800. ; 47:11-12, s. 1211-1217
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Tidskriftsartikel (refereegranskat)abstract
- The dose response of an alanine-agarose gel, analyzed by ESR spectrometry, and the stability of the radiation-induced free radicals have been investigated. The stability of the ESR signal is higher for dosimeter samples analyzed at 77 K than for dried samples, analyzed at room-temperature. The dose response is linear to within ±2% in the absorbed dose interval 2–100 Gy. The variations in spectral line shape were analyzed at temperatures between 77 and 270 K. The experimental ESR spectrum at 77 K was compared with a simulated spectrum of polycrystals of L-α-alanine.
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| 7. |
- Olsson, Sara K., 1970-, et al.
(författare)
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Development of ammonium tartrate as an ESR dosimeter material for clinical purposes
- 2000
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Ingår i: Applied Radiation and Isotopes. - 0969-8043 .- 1872-9800. ; 52:5, s. 1235-1241
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Tidskriftsartikel (refereegranskat)abstract
- The crystalline substance ammonium tartrate is investigated with respect to its suitability as a clinical dosimetry material. The properties investigated are: the radical stability for absorbed doses relevant for clinical use, the improvement in sensitivity when the crystals are deuterated and the linear electron tranfer (LET)-dependence. After photon irradiation to an absorbed dose of 20 Gy, the signal increases rapidly during the first 6 h. After this period, the changes are more moderate and can be corrected for. The signal-to-noise ratio of irradiated ammonium tartrate is twice the corresponding value of alanine. By deuterating the crystals, the sensitivity can be further improved by a factor of 1.4. As expected, the signal decreases with increasing LET of the radiation, but no changes in the spectrum shape was observed.
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| 8. |
- Tolmachev, Vladimir, et al.
(författare)
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Diffusion based separation methods : Dry distillation of zinc, cadmium and mercury isotopes from irradiated targets
- 1997
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Ingår i: Applied Radiation and Isotopes. - 0969-8043 .- 1872-9800. ; 48:5, s. 565-569
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Tidskriftsartikel (refereegranskat)abstract
- Diffusion-based separation methods allow the extraction of produced radionuclides with a low loss of target material, which is of special importance when enriched target material is used. We present a simple, non-destructive and rapid method to separate radioactive isotopes of IIB group elements (zinc, cadmium and mercury) from IB group metal targets irradiated with protons. Irradiated target foils were heated to a temperature 20°C below the melting point of the target materials. During these conditions at least 90% of the desired radioactivity was evaporated with negligible loss of target material. Separation time was 15 min for mercury, 60 min for cadmium and 120 min for zinc.
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| 9. |
- Tolmachev, Vladimir, et al.
(författare)
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Production of 61Cu from a natural nickel target
- 1998
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Ingår i: Applied Radiation and Isotopes. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0969-8043 .- 1872-9800. ; 49:1-2, s. 79-81
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Tidskriftsartikel (refereegranskat)
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| 10. |
- Vestad, T.A., et al.
(författare)
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EPR dosimetric properties of formates
- 2003
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Ingår i: Applied Radiation and Isotopes. - 0969-8043 .- 1872-9800. ; 59:2-3, s. 181-188
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Tidskriftsartikel (refereegranskat)abstract
- As a part of a program to develop an electron paramagnetic resonance (EPR) dosimeter suited for clinical use (doses in the cGy range), polycrystalline samples of lithium formate monohydrate (HCO2Li·H 2O), magnesium formate dihydrate (C2H2O 4Mg·2H2O), and calcium formate (C2H 2O4Ca) have been examined. L-Alanine was included for comparison and reference. Samples were irradiated with 60Co ?-rays and 60-220kV X-rays. The dosimeter response was assessed using the peak-to-peak amplitude of the first-derivative EPR spectrum. Dose-response curves for the 60Co ?-irradiated samples were constructed, and the dependences of the response on the photon energy, microwave power, and modulation amplitude were studied. Stability of the irradiation products upon storage (signal fading) was also investigated. Lithium formate monohydrate is by far the best candidate of the tested formates, suitable for measuring doses down to approximately 0.1Gy. Lithium formate monohydrate is more sensitive than alanine by a factor of 5.6-6.8 in the tested photon energy range, it exhibits no zero-dose signal and shows a linear dose response in the dose range from 0.2 to 1000Gy. Its EPR signal was found unchanged in shape and intensity 1 week after irradiation to 10Gy. Various less favorable properties rendered the other formates generally unsuitable, although calcium formate exhibits some interesting EPR dosimetric properties. © 2003 Elsevier Ltd. All rights reserved.
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| 11. |
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| 12. |
- Alhassan, E., et al.
(författare)
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TENDL-based evaluation and adjustment of p+111Cd between 1 and 100 MeV
- 2023
-
Ingår i: Applied Radiation and Isotopes. - : Elsevier. - 0969-8043 .- 1872-9800. ; 198
-
Tidskriftsartikel (refereegranskat)abstract
- Proton induced reaction data are needed in the optimization of various radioisotope production routes, among others. In this work, the evaluation of proton-induced reactions on 111Cd between 1 and 100 MeV using the TALYS code system within an iterative Bayesian Monte Carlo (iBMC) framework, is presented. The method involves the simultaneous variation of a large number of nuclear reaction models included in the TALYS code system as well as their parameters. Each random TALYS calculation yields a vector of calculated values of cross section observables as well as the angular distributions, among others, which were compared with corresponding vectors of carefully selected differential experimental data for reaction channels where data were available. The random nuclear data file with the maximum likelihood function value obtained from combining the individual chi 2s computed for the considered reaction channels was chosen as the parent vector and the starting point for the generation of a further set of random TALYS calculations. This was repeated multiple times until a targeted convergence of 5% was reached. The final evaluated file was compared with available experimental data from the EXFOR database as well as with the evaluations from the TENDL-2021 and JENDL5.0 libraries, and found to compare favorably.
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| 13. |
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| 14. |
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| 15. |
- Aneheim, Emma, 1982, et al.
(författare)
-
N-[2-(maleimido)ethyl]-3-(trimethylstannyl)benzamide, a molecule for radiohalogenation of proteins and peptides
- 2015
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Ingår i: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 96, s. 1-5
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Tidskriftsartikel (refereegranskat)abstract
- In this work a new coupling reagent, N[2-(maleimido)ethyl]-3-(trimethylstannyl)benzamide, for radiohalogenation has been synthesized and characterized. The reagent is intended to either be attached to reduced disulfide bridges of proteins (making the halogenation site-specific) or to free terminal cysteine groups on peptides. The new reagent was also shown to be easily halogenated with inactive bromine and iodine as well as I-125 and At-211, indicating potential use within targeted radiotherapy.
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| 16. |
- Bargholts, Christof, et al.
(författare)
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A new laboratory for measurements of low-level radioactivity
- 2008
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Ingår i: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 66:10, s. 1443-1449
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Tidskriftsartikel (refereegranskat)abstract
- A laboratory for measuring low-level radioactivity has been built at the AlbaNova University Center in Stockholm. Low-level concrete in combination with a 5 cm iron lining provide an average photon fluency rate from terrestrial sources at least a factor of 40 below that in the common laboratories of the Center. The radon activity inside the laboratory has been measured to (3 +/- 2) Bq m(-3). Material considerations are discussed. Construction and performance of the laboratory, as well as the present instrumentation, is described.
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| 17. |
- Björke, Henrik, et al.
(författare)
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Automated, high-resolution cellular retention and uptake studies in vitro
- 2006
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Ingår i: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 64:8, s. 901-905
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Tidskriftsartikel (refereegranskat)abstract
- This report describes an automated method for the measurements of cellular retention and uptake of radiolabeled proteins interacting with cell-surface receptors on intact cancer cells. A complete uptake and retention measurement was performed in one cell dish using a rotating radioimmunoassay (RIA) principle. Compared to common manual measurements, rotating RIA saved both labor time and reagents and provided real-time binding traces with superior time-resolution. The rotating RIA retention profiles for different interactions agreed with retention times reported in the literature.
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| 18. |
- Björke, Henrik, et al.
(författare)
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Measuring the affinity of a radioligand with its receptor using a rotating cell dish with in situ reference area
- 2006
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Ingår i: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 64:1, s. 32-37
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Tidskriftsartikel (refereegranskat)abstract
- This report describes a semi-automated method for the measurement of affinity of radiolabeled ligands interacting with cell-surface receptors on intact cancer cells. The method saves labor time and reagents compared to common manual measurements. A complete affinity measurement can be performed in one cell dish by using a target cell area and a reference area and repeatedly measure the differential activity (i.e. target activity-reference activity). The affinities obtained for different ligand-receptor interactions agreed with affinities reported in the literature.
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| 19. |
- Champion, C., et al.
(författare)
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Dose point kernels in liquid water : An intra-comparison between GEANT4-DNA and a variety of Monte Carlo codes
- 2014
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Ingår i: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 83, s. 137-141
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Tidskriftsartikel (refereegranskat)abstract
- Modeling the radio-induced effects in biological medium still requires accurate physics models to describe the interactions induced by all the charged particles present in the irradiated medium in detail. These interactions include inelastic as well as elastic processes. To check the accuracy of the very low energy models recently implemented into the GEANT4 toolkit for modeling the electron slowing-down in liquid water, the simulation of electron dose point kernels remains the preferential test. In this context, we here report normalized radial dose profiles, for mono-energetic point sources, computed in liquid water by using the very low energy GEANT4-DNA physics processes available in the GEANT4 toolkit. In the present study, we report an extensive intra-comparison of profiles obtained by a large selection of existing and well-documented Monte-Carlo codes, namely, EGSnrc, PENELOPE, CPA100, FLUKA and MCNPX.
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| 20. |
- Czub, Joanna, et al.
(författare)
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Biological effects of mixed-ion beams. Part 1 : Effect of irradiation of the CHO-K1 cells with a mixed-ion beam containing the carbon and oxygen ions
- 2018
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Ingår i: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 139, s. 304-309
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Tidskriftsartikel (refereegranskat)abstract
- Carbon and oxygen ions were accelerated simultaneously to estimate the effect of irradiation of living cells with the two different ions. This mixed ion beam was used to irradiate the CHO-K1 cells, and a survival test was performed. The type of the effect of the mixed ion beam on the cells was determined with the isobologram method, whereby survival curves for irradiations with individual ion beams were also used. An additive effect of irradiation with the two ions was found.
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| 21. |
- Czub, Joanna, et al.
(författare)
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Biological effects of mixed-ion beams. Part 2 : The relative biological effectiveness of CHO-K1 cells irradiated by mixed- and single-ion beams
- 2019
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Ingår i: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 150, s. 192-198
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Tidskriftsartikel (refereegranskat)abstract
- The relative biological effectiveness (RBE) values were determined for single- and mixed-ion beams containing carbon and oxygen ions. The CHO-K1 cells were irradiated with beams with the linear energy transfer (LET) values of 236-300 and 461-470 keV/mu m for C-12 and O-16 ions, respectively. The RBE was estimated as a function of dose, survival fraction (SF) and LET. The SF was not affected by varying contributions of the constituent ions to the total mixed dose. The RBE has the same value for single-ion exposures with ions with LET 300 (C-12) and 470 keV/mu m (O-16).
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| 22. |
- Dance, D R, et al.
(författare)
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Breast dosimetry
- 1999
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Ingår i: Applied Radiation and Isotopes. - 0969-8043 .- 1872-9800. ; 50, s. 185-203
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Tidskriftsartikel (refereegranskat)
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| 23. |
- Dian, E., et al.
(författare)
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Neutron activation and prompt gamma intensity in Ar/CO2-filled neutron detectors at the European Spallation Source
- 2017
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Ingår i: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 128, s. 275-286
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Tidskriftsartikel (refereegranskat)abstract
- Monte Carlo simulations using MCNP6.1 were performed to study the effect of neutron activation in Ar/CO2 neutron detector counting gas. A general MCNP model was built and validated with simple analytical calculations. Simulations and calculations agree that only the Ar-40 activation can have a considerable effect. It was shown that neither the prompt gamma intensity from the Ar-40 neutron capture nor the produced Ar-41 activity have an impact in terms of gamma dose rate around the detector and background level.
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| 24. |
- dos Santos Matias, Lucilio, et al.
(författare)
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Characterization of the radiation field surrounding the Leksell Gamma Knife® and shielding applications
- 2023
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Ingår i: Applied Radiation and Isotopes. - 0969-8043 .- 1872-9800. ; 198
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study is to improve the characterization and modeling of the radiation field surrounding the Leksell Gamma Knife®-PerfexionTM. The improved characterization of the radiation field enables more accurate shielding calculations to be performed for the areas adjacent to the treatment room. With the aid of a high-purity germanium detector and a satellite dose rate meter, ?-ray spectra and ambient dose equivalent H*(10) data were acquired at various locations in the field of a Leksell Gamma Knife unit in a treatment room at Karolinska University Hospital, Sweden. These measurements were used to validate the results of the PEGASOS Monte Carlo simulation system with a PENELOPE kernel. The levels of the radiation that passes through the shielding of the machine (leakage radiation) are shown to be much lower than what is suggested by various bodies, e.g. the National Council on Radiation Protection and Measurements, to be used when calculating radiation shielding barriers. The results clearly indicate that Monte Carlo simulations may be used in structural shielding design calculations for γ? rays from the Leksell Gamma Knife.
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| 25. |
- Francis, Z., et al.
(författare)
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Molecular scale track structure simulations in liquid water using the Geant4-DNA Monte-Carlo processes
- 2011
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Ingår i: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 69:1, s. 220-226
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a study of energy deposits induced by ionising particles in liquid water at the molecular scale Particles track structures were generated using the Geant4-DNA processes of the Geant4 Monte-Carlo toolkit These processes cover electrons (0 025 eV-1 MeV) protons (1 keV-100 MeV) hydrogen atoms (1 keV-100 MeV) and alpha particles (10 keV-40 MeV) including their different charge states Electron ranges and lineal energies for protons were calculated in nanometric and micrometric volumes
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| 26. |
- Gedda, Lars, et al.
(författare)
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Real-time immunohistochemistry analysis of embedded tissue
- 2010
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Ingår i: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 68:12, s. 2372-2376
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Tidskriftsartikel (refereegranskat)abstract
- We present a novel analysis of membrane-protein expression in tissue sections based on semi-automatic real-time measurement using LigandTracer(®) technology. A commercial antiHER2 antibody developed for immunohistochemistry used in this setup was revealed to have sub-optimal interaction with tissue when analyzed as recommended for immunohistochemistry. We therefore think that real-time measurement of tissue, offering direct and quantitative membrane-protein interaction analysis, can lead to improved reproducibility and eliminate the subjective operator dependences that classical immunohistochemsitry suffers from.
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| 27. |
- He, Qinggang, et al.
(författare)
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Electrochemical nucleophilic synthesis of di-tert-butyl-(4-[F-18]fluoro-1,2-phenylene)-dicarbonate
- 2014
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Ingår i: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 92, s. 52-57
-
Tidskriftsartikel (refereegranskat)abstract
- An electrochemical method with the ability to conduct F-18-fluorination of aromatic molecules through direct nucleophilic fluorination of cationic intermediates is presented in this paper. The reaction was performed on a remote-controlled automatic platform. Nucleophilic electrochemical fluorination of tert-butyloxycarbonyl (Boc) protected catechol, an intermediate model molecule for the positron emission tomography (PET) probe (3,4-dihydroxy-6-[F-18]fluoro-L-phenylalanine), was performed. Fluorination was achieved under potentiostatic anodic oxidation in acetonitrile containing Et3N center dot 3HF and other supporting electrolytes. Radiofluorination efficiency was influenced by a number of variables, including the concentration of the precursor, concentration of Et3N center dot 3HF, type of supporting electrolyte, temperature and time, as well as applied potentials. Radiofluorination efficiency of 10.4 +/- 0.6% (n=4) and specific activity of up to 43 GBq/mmol was obtained after 1 h electrolysis of 0.1 M of 4-tert-butyl-diboc-catechol in the acetonitrile solution of Et3N center dot 3HF (0.033 M) and NBu4PF6 (0.05 M). Density functional theory (DFT) was employed to explain the tert-butyl functional group facilitation of electrochemical oxidation and subsequent fluorination.
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| 28. |
- Holmgren, S., et al.
(författare)
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Handling interferences in Sr-89 and Sr-90 measurements of reactor coolant water: A method based on strontium separation chemistry
- 2014
-
Ingår i: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 90:Aug., s. 94-101
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Tidskriftsartikel (refereegranskat)abstract
- Measurements for determining the activity of Sr-89 and Sr-90 in reactor coolant water are associated with limitations due to interferences from radionuclides with similar chemical properties and beta(-)-energies. From a measurement bias point-of-view these interferences would result mainly in an overestimated activity concentration of Sr-90. In order to address the interference problem, a common and well-known method was used in order to show the need for sufficient decontamination. An improvement was achieved by taking the sample through two initial strontium separations in order to increase the decontamination factor. This method determines the activity concentration of Sr-89 and Sr-90, via its daughter nuclide Y-90, by Cherenkov counting. This work is primarily based on theoretical calculations of strontium-, yttrium- and other potential interfering radionuclide ratios after instant fission. The work done to confirm the theoretical calculations were carried through on spiked strontium standard solutions and fresh reactor coolant water. The reactor coolant water was known to contain interferences at a composition resembling that of instant fission. The detection limit for double separation was calculated to 0.17 Bq/kg for Sr-90 and 0.38 Bq/kg for Sr-89. When using methods that solely rely on strontium resins, this paper shows that the decontamination factor (DF) is significantly higher when using double separation than that of a single separation. The paper also shows that the DF of an initial double strontium separation is as effective when it comes to removing high ratio interferences as separations done with both Sr- and Ln-resin (EiChrom Technologies, Inc., 2003; Tovedal at at, 2009b). However, 'old' samples, where e.g. Ba-140 and Sr-89 has decayed, does not benefit from double separation. Furthermore, samples with low ratios of interfering radionuclides does not benefit from using this method either, seeing as this is a more time consuming method due to the double separations.
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| 29. |
- Holmgren, S., et al.
(författare)
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Time optimization of Sr-90 measurements: Sequential measurement of multiple samples during ingrowth of Y-90
- 2016
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Ingår i: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 110, s. 150-154
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this paper is to contribute to a more rapid determination of a series of samples containing Sr-90 by making the Cherenkov measurement of the daughter nuclide Y-90 more time efficient. There are many instances when an optimization of the measurement method might be favorable, such as; situations requiring rapid results in order to make urgent decisions or, on the other hand, to maximize the throughput of samples in a limited available time span. In order to minimize the total analysis time, a mathematical model was developed which calculates the time of ingrowth as well as individual measurement times for n samples in a series. This work is focused on the measurement of Y-90 during ingrowth, after an initial chemical separation of strontium, in which it is assumed that no other radioactive strontium isotopes are present. By using a fixed minimum detectable activity (MDA) and iterating the measurement time for each consecutive sample the total analysis time will be less, compared to using the same measurement time for all samples. It was found that by optimization, the total analysis time for 10 samples can be decreased greatly, from 21 h to 6.5 h, when assuming a MDA of 1 Bq/L and at a background count rate of approximately 0.8 cpm.
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| 30. |
- Kastlander, Johan, et al.
(författare)
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In-situ method to determine depth distribution of buried activity
- 2011
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Ingår i: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 69:5, s. 773-779
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Tidskriftsartikel (refereegranskat)abstract
- A method is described to determine the depth distribution of buried activity offering an alternative to conventional soil sampling and laboratory analysis by in-situ measurements with small detectors inserted into the ground. As ad demonstration of the method small-scale variations in the distribution of Cs-137 in a riparian marsh in central-eastern Sweden are determined using lanthanum bromide detectors (LaBr3). The results show variations of the activity ranging between 400 and 2200 kBq/m^2 over an area not exceeding 350 m^2. The decrease of the average activity since 2003 coincides with the physical decay indicating that no net redistribution of activity into this part of the marsh has occurred during the inter weening years.
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| 31. |
- Kastlander, J., et al.
(författare)
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Uncertainties in calculated correction factors for true coincidence-summing (TCS)
- 2017
-
Ingår i: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 122, s. 174-179
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this work was to estimate the uncertainties in Monte Carlo calculated correction factors for true coincidence summing (TCS). In this work TCS-factors and their uncertainties were calculated for 134Cs and then the corrected activities compared to empirical data. The study was carried out using a close-end coaxial p-type detector (Ø80 mm×54.5 mm, 80% relative efficiency) and a cylindrical glass fiber sample (Ø60 mm×14 mm). It was shown that the uncertainty in the calculated correction factor for the primary gamma ray was below 0.5%, which means it will not contribute significantly to the combined uncertainty in an activity measurement for e.g. environmental monitoring.
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| 32. |
- Kossert, Karsten, et al.
(författare)
-
Activity standardization of two enriched 40K solutions for the determination of decay scheme parameters and the half-life
- 2022
-
Ingår i: Applied Radiation and Isotopes. - : Elsevier. - 0969-8043 .- 1872-9800. ; 188
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper we describe experiments on two enriched K-40 solutions to accurately determine decay data. The first solution was measured in 2004/2005 by means of a gamma-ray spectrometer with low background and a liquid scintillation (LS) counter to apply the CIEMAT/NIST efficiency tracing method. A combination of results yields an emission probability of the 1461 keV gamma-rays of P-gamma = 0.1030(11) which is lower than current results of data evaluations. The activity concentration of the second solution was also determined by means of LS counting, but here, the CIEMAT/NIST efficiency tracing method as well as the TDCR method were applied. Again, the result was combined with that of independent gamma-ray spectrometry and the gamma-ray emission probability was found to be P-gamma = 0.1029(9) in good agreement with the result obtained from the first solution. A combination of both experiments yields P-gamma = 0.1029(9). The spectra of a TriCarb LS counter were carefully analyzed and a beta minus emission probability P beta- = 0.8954(14) was determined. The new results for P-gamma and P-beta-indicate that the overall probability of the decay via EC in recent data evaluations is overestimated. The LS counting efficiencies were computed with a stochastic model and up-to-date calculations of the beta spectrum and fractional EC probabilities were used. The final activity result of the second solution is combined with the outcome of a comprehensive isotopic analysis to determine the half-life of K-40 which is found to be 1.2536(27) .10(9) years. All above-stated uncertainties are standard uncertainties (k = 1).
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| 33. |
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| 34. |
- Lindahl, Patric, et al.
(författare)
-
Total dissolution of environmental samples for the determination of uranium and thorium by ICP-MS and alpha-particle spectrometry
- 2022
-
Ingår i: Applied Radiation and Isotopes. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0969-8043 .- 1872-9800. ; 181
-
Tidskriftsartikel (refereegranskat)abstract
- A low-cost total dissolution method for accurate determination of uranium and thorium isotopes in environmental samples (soil and sediment) was introduced, optimised and validated. The method included alkaline fusion based on sodium hydroxide (NaOH) and sodium peroxide (Na2O2), followed by sequential extraction chromatography separation and measurements with ICP-MS or alpha-particle spectrometry. The overall chemical recoveries for U and Th for the entire procedure were about 80% and 90%, respectively. The U-238 contribution from partial dissolution of the nickel crucibles accounted for about 80% of the total background activity.
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| 35. |
- Lund, Eva, et al.
(författare)
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Formates and dithionates : sensitive EPR-dosimeter materials for radiation therapy
- 2005
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Ingår i: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 62:2, s. 317-324
-
Tidskriftsartikel (refereegranskat)abstract
- Polycrystalline, formates and dithionates are promising materials for EPR dosimetry, as large yields of radiation induced stable radicals are formed with a linear dose response. Rapid spin relaxation rates were detected in many of the substances, indicating that a high microwave power can be applied during EPR acquisition in order to improve sensitivity. Different techniques used to further improve the sensitivity, such as the replacement of Li-7 with Li-6 or exchange of protons with deuterons in the corresponding crystalline matrices and metal ion doping are discussed. It is concluded that formates and dithionates may be up to 10 times as sensitive as L-alpha-alanine. (C) 2004 Elsevier Ltd. All rights reserved.
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| 36. |
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| 37. |
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| 38. |
- Matsson, Ingvar, et al.
(författare)
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On-site Gamma-ray Spectroscopic Measurements of Fission Gas Release in Irradiated Nuclear Fuel
- 2007
-
Ingår i: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 65:1, s. 36-45
-
Tidskriftsartikel (refereegranskat)abstract
- An experimental, non-destructive in-pool, method for measuring fission gas release (FGR) in irradiated nuclear fuel has been developed. Using the method, a significant number of experiments have been performed in-pool at several nuclear power plants of the BWR type. The method utilises the 514 keV gamma-radiation from the gaseous fission product Kr-85 captured in the fuel rod plenum volume. A submergible measuring device (LOKET) consisting of an HPGe-detector and a collimator system was utilised allowing for single rod measurements on virtually all types of BWR fuel. A FGR database covering a wide range of burn-ups (up to average rod burn-up well above 60 MWd/kgU), irradiation history, fuel rod position in cross section and fuel designs has been compiled and used for computer code benchmarking, fuel performance analysis and feedback to reactor operators. Measurements clearly indicate the low FGR in more modern fuel designs in comparison to older fuel types.
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| 39. |
- Mukhopadhyay, Nitai D, et al.
(författare)
-
Estimating statistical uncertainty of Monte Carlo efficiency-gain in the context of a correlated sampling Monte Carlo code for brachytherapy treatment planning with non-normal dose distribution
- 2012
-
Ingår i: Applied Radiation and Isotopes. - UK : Pergamon. - 0969-8043 .- 1872-9800. ; 70:1, s. 315-323
-
Tidskriftsartikel (refereegranskat)abstract
- Correlated sampling Monte Carlo methods can shorten computing times in brachytherapy treatment planning. Monte Carlo efficiency is typically estimated via efficiency gain, defined as the reduction in computing time by correlated sampling relative to conventional Monte Carlo methods when equal statistical uncertainties have been achieved. The determination of the efficiency gain uncertainty arising from random effects, however, is not a straightforward task specially when the error distribution is non-normal. The purpose of this study is to evaluate the applicability of the F distribution and standardized uncertainty propagation methods (widely used in metrology to estimate uncertainty of physical measurements) for predicting confidence intervals about efficiency gain estimates derived from single Monte Carlo runs using fixed-collision correlated sampling in a simplified brachytherapy geometry. A bootstrap based algorithm was used to simulate the probability distribution of the efficiency gain estimates and the shortest 95% confidence interval was estimated from this distribution. It was found that the corresponding relative uncertainty was as large as 37% for this particular problem. The uncertainty propagation framework predicted confidence intervals reasonably well; however its main disadvantage was that uncertainties of input quantities had to be calculated in a separate run via a Monte Carlo method. The F distribution noticeably underestimated the confidence interval. These discrepancies were influenced by several photons with large statistical weights which made extremely large contributions to the scored absorbed dose difference. The mechanism of acquiring high statistical weights in the fixed-collision correlated sampling method was explained and a mitigation strategy was proposed.
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| 40. |
- Perot, B., et al.
(författare)
-
Measurement of 14 MeV neutron-induced prompt gamma-ray spectra from 15 elements found in cargo containers
- 2008
-
Ingår i: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 66:4, s. 421-434
-
Tidskriftsartikel (refereegranskat)abstract
- Within the EURopean Illicit TRAfficking Countermeasures Kit (EURITRACK) project, the gamma-ray spectra produced in a series of materials by 14-MeV tagged-neutron beams have been collected in the inspection portal equipped with large volume Nal(Tl) detectors, in order to build a database of signatures for various elements: C, N, O, Na, Al, Si, Cl, K, Ca, Cr, Fe, Ni, Cu, Zn, Pb. The measured spectra have been compared with prediction from Monte Carlo simulations to verify the consistency of the relevant nuclear data inputs. This library of measured 14-MeV neutron-induced gamma-ray spectra is currently used in a data processing algorithm to unfold the energy spectra of the transported goods into elementary contributions, thus allowing material identification.
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| 41. |
- Pham, M. K., et al.
(författare)
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A new Certified Reference Material for radionuclides in Irish sea sediment (IAEA-385)
- 2008
-
Ingår i: APPLIED RADIATION AND ISOTOPES. - : Elsevier BV. - 1872-9800 .- 0969-8043. ; 66:11, s. 1711-1717
-
Konferensbidrag (refereegranskat)abstract
- A new Certified Reference Material (CRM) for radionuclides in sediment (IAEA-385) is described and the results of the certification process are presented. Eleven radionuclides (K-40, Cs-137, Ra-226, Ra-228, Th-230, Th-232, U-234, U-238, Pu-238, Pu239+240 and Am-241) have been certified and information mass activities with 95% confidence intervals are given for seven other radionuclides (Sr-90, Pb-210(Po-210), U-235, Pu-239, Pu-240 and Pu-241). Results for less frequently reported radionuclides (Co-60, Tc-99, Cs-134, Eu-155, Ra-224 and Np-239) and information on some activity and mass ratios are also reported. The CRM can be used for quality assurance/quality control of the analysis of radionuclides in sediment samples, for the development and validation of analytical methods and for training purposes. (C) 2008 IAEA. Published by Elsevier Ltd. All rights reserved.
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| 42. |
- Pham, M. K., et al.
(författare)
-
Certified reference material for radionuclides in fish flesh sample IAEA-414 (mixed fish from the Irish Sea and North Sea)
- 2006
-
Ingår i: Proceedings of the 15th International Conference on Radionuclide Metrology and its Applications (Applied Radiation and Isotopes). - Amsterdam : Elsevier BV. - 1872-9800 .- 0969-8043. ; 64:10-11, s. 1253-1259
-
Konferensbidrag (refereegranskat)abstract
- A certified reference material (CRM) for radionuclides in fish sample IAEA-414 (mixed fish from the Irish Sea and North Seas) is described and the results of the certification process are presented. Nine radionuclides (K-40, Cs-137, Th-232, U-234, U-235, U-238, Pu-238, Pu239+240 and Am-241) were certified for this material. Information on massic activities with 95% confidence intervals is given for six other radionuclides (Sr-90, Pb-210(Po-210), Ra-226, Pu-239, Pu-240 Pu-241). Less frequently reported radionuclides (Tc-99, I-129, Th-228, Th-230 and Np-217) and information on some activity and mass ratios are also included. The CRM can be used for quality assurance/quality control of the analysis of radionuclides in fish sample, for the development and validation of analytical methods and for training purposes. The material is available from IAEA, Vienna, in 100 g units.
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| 43. |
- Pham, M. K., et al.
(författare)
-
Certified Reference Material IAEA-446 for radionuclides in Baltic Sea seaweed
- 2014
-
Ingår i: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 87, s. 468-474
-
Tidskriftsartikel (refereegranskat)abstract
- A Certified Reference Material (CRM) for radionuclides in seaweed (Fucus vesiculosus) from the Baltic Sea (IAEA-446) is described and the results of the certification process are presented. The K-40, Cs-132, U-234 and Pu239+240 radionuclides were certified for this material, and information values for 12 other radionuclides (Sr-90, Tc-99, Pb-210 (Po-210), Ra-226, Ra-228, Th-228, Th-230, Th-232, U-235, U-238, Pu-239 and Pu-240) are presented. The CRM can be used for Quality Assurance/Quality Control of analysis of radionuclides in seaweed and other biota samples, as well as for development and validation of analytical methods, and for training purposes. (C) 2013 Elsevier Ltd. All rights reserved.
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| 44. |
- Qiao, Jixin, et al.
(författare)
-
Speciation analysis of 129I, 137Cs, 232Th, 238U, 239Pu and 240Pu in environmental soil and sediment
- 2012
-
Ingår i: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 70:8, s. 1698-1708
-
Tidskriftsartikel (refereegranskat)abstract
- The environmental mobility and bioavailability of radionuclides are related to their physicochemical forms, namely species. We here present a speciation analysis of important radionuclides including I-129 (also I-127), Cs-137, Th-232, U-238 and plutonium isotopes (Pu-239 and Pu-240) in soil (IAEA-375) and sediment (NIST-4354) standard reference materials and two fresh sediment samples from Ovre Heimdalsvatnet Lake, Norway. A modified sequential extraction protocol was used for the speciation analysis of these samples to obtain fractionation information of target radionuclides. Analytical results reveal that the partitioning behaviour, and thus the potential mobility and bioavailability, are exclusively featured for the individual radionuclide. Iodine is relatively mobile and readily binds to organic matter, while plutonium is mainly bound to both organic matter and nitric acid leachable fractions. Thorium is predominated in nitric acid leachable fraction and caesium is primarily observed in nitric acid and aqua regia leachable fractions and residue. Our analytical results reveal that around 50% of uranium might still remain in the residue which could not be extracted with aggressive acid, namely, aqua regia.
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| 45. |
- Ramebäck, Henrik, 1967, et al.
(författare)
-
A Monte Carlo method for calculation of the characteristic limits decision threshold and detection limit in low-level radioactivity measurements
- 2021
-
Ingår i: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 178
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, calculation of decision threshold and detection limit expressed in counts for low-level radioactivity measurements were evaluated and compared to a Monte Carlo method for the case of paired Poisson-distributed observations, i.e. for discrete variables. The calculated characteristic limits obtained from Monte Carlo calculations were compared with analytical expressions given in literature. The results in this study show that the equations given by Currie are in good agreement with the results from the Monte Carlo calculations simulating nuclear counting applications with a low number of observed counts. An exception is observed for a background corresponding to zero counts. This study also shows that at a low number of counts, the specific boundary conditions of the interval that represents counts corresponding to the presence of the analyte (>or ≥), have an impact on the false positives and negatives rates as defined by the parameters α and β.
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| 46. |
- Ramebäck, Henrik, 1967, et al.
(författare)
-
Calculation of decision threshold and detection limit in radiometric measurements using a Monte Carlo Method
- 2020
-
Ingår i: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 156
-
Tidskriftsartikel (refereegranskat)abstract
- Calculation of the decision threshold and detection limit of a measurement, or measurement method, are crucial in order to decide if an analyte is present or not and with what confidence it can be quantified. That decision is important in view of possible actions if something would be detected. In this work, a method for calculating these limits using a Monte Carlo method is presented. In the Monte Carlo method any a priori distribution (e.g. normal distribution, rectangular distribution, triangular distribution) of an input quantity can be selected. Differences between the Monte Carlo calculated characteristic limits and the ones calculated according to ISO 11929:2010 is presented. Moreover, suggestions how to calculate the detection limit when it can not be calculated according to the ISO 11929:2010 are given.
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| 47. |
- Ramebäck, Henrik, 1967, et al.
(författare)
-
Gamma spectrometric measurement of uranium isotopic composition and mass in sintered UO 2 pellets using the efficiency transfer method
- 2023
-
Ingår i: Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 192, s. 110607-
-
Tidskriftsartikel (refereegranskat)abstract
- Gamma spectrometric measurements to determine the isotopic composition and total uranium mass in UO2 pellets (D = 7.5 mm; H = 3.5 mm, ρ = 10 g/cm3) were carried out. The required efficiency curve was obtained by applying the efficiency transfer method from a calibration standard (D = 65 mm; H = 20 mm) of a slightly acidified water solution. The average isotopic composition of ten UO2 pellets was consistent with values of natural uranium given by IUPAC. The average relative bias for the 235U/238U amount ratio was -0.73% using the 1001 keV gamma line for 238U and 0.50% using the 63 keV gamma line (186 keV was always used for 235U). For the total uranium mass, the mean deviation as compared to mass determinations using a balance was 5.5% using the 1001 keV gamma line for 238U and 4.3% using the 63 keV gamma line.
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| 48. |
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| 49. |
- Ramebäck, Henrik, 1967, et al.
(författare)
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Uncertainty evaluation in gamma spectrometric measurements: Uncertainty propagation versus Monte Carlo simulation
- 2018
-
Ingår i: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 142, s. 71-76
-
Tidskriftsartikel (refereegranskat)abstract
- Calculation and reporting of combined measurement uncertainties are important in decision making processes, and a more proper uncertainty estimation can reduce the risk and/or the cost associated with decisions for example after radiological incidents and in free release measurements of radioactive waste. However, sound decisions demand a sound uncertainty estimation. In this work we present the possible consequences when uncertainty propagation is applied to gamma-ray spectrometry measurements involving assumed probability density functions for an efficiency transfer having different metrological quality by comparison with Monte Carlo simulations.
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| 50. |
- Rondahl, Stina Holmgren, et al.
(författare)
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Evaluation of different methods for measuring 89Sr and 90Sr: Measurement uncertainty for the different methods as a function of the activity ratio
- 2018
-
Ingår i: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 140, s. 87-95
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Tidskriftsartikel (refereegranskat)abstract
- In case of a radiological emergency situation involving e.g. fission of uranium or plutonium, analysis of radioactive strontium will be of importance. The primary radionuclides of interest are90Sr, its progeny90Y and89Sr. A few days following an event,89Sr will be the predominant radioisotope of strontium. Most methods found in the literature are valid and applicable when measuring90Sr, but when samples contain both89Sr/90Sr interference problematics arise. How these interferences are dealt with will have an effect on the uncertainty of the90Sr determination. This work aims at evaluating three measurement approaches, all mentioned in the literature, with respect to the measurement uncertainty when determining90Sr in an emergency preparedness situation and to propose a suitable measurement strategy.
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