| 1. |
- Adolfsson, Emelie, et al.
(författare)
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Optimisation of an EPR dosimetry system for robust and high precision dosimetry
- 2014
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Ingår i: Radiation Measurements. - : Elsevier. - 1350-4487 .- 1879-0925. ; 70, s. 21-28
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Tidskriftsartikel (refereegranskat)abstract
- Clinical applications of electron paramagnetic resonance (EPR) dosimetry systems demand high accuracy causing time consuming analysis. The need for high spatial resolution dose measurements in regions with steep dose gradients demands small sized dosimeters. An optimization of the analysis was therefore needed to limit the time consumption. The aim of this work was to introduce a new smaller lithium formate dosimeter model (diameter reduced from standard diameter 4.5 mm to 3 mm and height from 4.8 mm to 3 mm). To compensate for reduced homogeneity in a batch of the smaller dosimeters, a method for individual sensitivity correction suitable for EPR dosimetry was tested. Sensitivity and repeatability was also tested for a standard EPR resonator and a super high Q (SHQE) one. The aim was also to optimize the performance of the dosimetry system for better efficiency regarding measurement time and precision. A systematic investigation of the relationship between measurement uncertainty and number of readouts per dosimeter was performed. The conclusions drawn from this work were that it is possible to decrease the dosimeter size with maintained measurement precision by using the SHQE resonator and introducing individual calibration factors for dosimeter batches. It was also shown that it is possible reduce the number of readouts per dosimeter without significantly decreasing the accuracy in measurements.
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| 2. |
- Andersson, P., et al.
(författare)
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An upgrade of the SCANDAL setup for measurements of elastic neutron scattering at 175 MeV
- 2010
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Ingår i: RADIATION MEASUREMENTS. - : Elsevier BV. ; 45:10, s. 1142-1144
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Konferensbidrag (refereegranskat)abstract
- The experimental setup SCANDAL used for measurements of the differential cross section for elastic and inelastic neutron scattering, has recently been upgraded with larger CsI scintillating detectors to enable measurements at energies up to 175 MeV. Measurements on Fe. Bi and Si have been carried out using the quasi mono-energetic neutron beam at the The Svedberg Laboratory, and data is under analysis. The experimental setup can be used for measurements on a wide range of target nuclei, including C and O, which are important for dosimetry applications. SCANDAL can also run in proton mode, for measurements of the (n,p) reaction. This paper describes the new experimental setup, and reports on its properties, such as energy resolution.
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| 3. |
- Bassinet, C., et al.
(författare)
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Retrospective radiation dosimetry using OSL of electronic components: Results of an inter-laboratory comparison
- 2014
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Ingår i: Radiation Measurements. - : Elsevier BV. - 1879-0925 .- 1350-4487. ; 71, s. 475-479
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Tidskriftsartikel (refereegranskat)abstract
- In the framework of the EU-FP7 MULTIBIODOSE project, two protocols using OSL of resistors removed from the circuit board of mobile phones were developed with the aim to use the resistors as fortuitous dosimeters in the event of a large scale radiological accident. This paper presents the results of an inter-laboratory comparison carried out under the umbrella of EURADOS. The two aims of this exercise were the validation of the MULTIBIODOSE protocols by a large number of laboratories and the dissemination of the method with the objective of preparing the basis for a network that could increase Europe's response capacity in the case of a mass casualty radiological emergency. Twelve institutes from eleven European countries and one institute from the USA, with various degrees of expertise in OSL dosimetry, took part in the OSL inter-laboratory comparison. Generally, a good agreement within uncertainties was observed between estimated and nominal doses. (C) 2014 Elsevier Ltd. All rights reserved.
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| 4. |
- Bevilacqua, Riccardo, et al.
(författare)
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Neutron induced light-ion production from iron and bismuth at 175 MeV
- 2010
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Ingår i: RADIATION MEASUREMENTS. - : Elsevier BV. ; 45:10, s. 1145-1150
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Konferensbidrag (refereegranskat)abstract
- We have measured light-ion (p, d, t, He-3 and alpha) production in the interaction of 175 MeV neutrons with iron and bismuth with low-energy thresholds and for a wide angular range (from 20 degrees to 160 degrees, in steps of 20 degrees). Measurements have been performed with the Medley setup, semi-permanently installed at the The Svedberg Laboratory, Uppsala (Sweden), where a quasi-monoenergetic neutron beam is available and well characterized. Medley is a conventional spectrometer system and consists of eight telescopes, each of them composed of two silicon surface barrier detectors, to perform particle identification, and a CsI(Tl) scintillator to fully measure the kinetic energy of the produced light-ions. We report preliminary double-differential cross sections for production of protons, deuterons and tritons in comparison with model calculations using TALYS-1.0 code. These show better agreement for the production of protons, while the theoretical calculations seem to overestimate the experimental production of deuterons and tritons.
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| 5. |
- Enger, Shirin A., et al.
(författare)
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Dosimetry for gadolinium neutron capture therapy (GdNCT)
- 2013
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Ingår i: Radiation Measurements. - : Elsevier BV. - 1879-0925 .- 1350-4487. ; 59, s. 233-240
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Tidskriftsartikel (refereegranskat)abstract
- Background Gadolinium (Gd) neutron capture therapy (GdNCT) is based on a neutron capture reaction (NCR) that involves emission of both short and long range products. The aim of this study was to investigate both the microscopic and macroscopic contributions of the absorbed dose involved in GdNCT. Methods Cylindrical containers with diameters 1-30 mm filled with a solution of Gd were irradiated with epithermal neutrons. The background neutron dose as well as the prompt gamma dose has been calculated and measured by means of film dosimetry for the largest cylinder. Monte Carlo codes MCNP5(b) and GEANT4 have been utilized for calculation the absorbed dose. Results and discussion Results from the film dosimetry are in agreement with the calculations for high doses while for low doses the measured values are higher than the calculated results. For the largest cylinder, the prompt gamma dose from GdNCR neutron is at least five times higher than the background dose. For a cell cluster model, in the first 0.1 mm the major contribution to the absorbed dose is from IC electrons. If Gd atoms were homogeneously distributed in the nuclei of all tumour cells, capture events between neutron and Gd atoms close to DNA could kill the tumour cells and give cross-fire dose from IC electrons to the cells located in the 0.1 mm range. Conclusions For a correct GdNCT dosimetry both microscopic part of the dose delivered by short-range low energy electrons and macroscopic part delivered by the prompt gamma should be considered.
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| 6. |
- Ersmark, T., et al.
(författare)
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Influence of geometry model approximations on Geant4 simulation results of the Columbus/ISS radiation environment
- 2007
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Ingår i: Radiation Measurements. - : Elsevier BV. - 1350-4487 .- 1879-0925. ; 42, s. 1342-1350
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Tidskriftsartikel (refereegranskat)abstract
- The influence of geometry model approximations on Geant4 Monte Carlo simulation results of the radiation environment on-board the Columbus module of the International Space Station (ISS) has been investigated. Three geometry models of Columbus with different levels of detail and a geometry model of ISS have been developed. These geometries have been used for Geant4 simulations of the radiation environment inside Columbus induced by trapped protons and Galactic Cosmic Ray protons. Simulated dose rates and particle spectra on-board Columbus for each of the three Columbus models, with or without the ISS geometry model included, are presented and compared. From comparisons of simulated dose rates and particle spectra for the three different geometry models it was found that the most detailed geometry model (750 volumes) produced results similar to a much less detailed model (23 volumes). The most detailed geometry model was concluded to be a sufficiently detailed approximation of the physical Columbus for the purpose of proton induced space radiation studies. The simulated dose rates are compatible with measurements on-board the ISS. The simulation results also show that an increase in shielding thickness decreases the simulated dose rate induced by trapped protons. For Galactic Cosmic Ray protons the dose rate remains unchanged or is slightly increased.
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| 7. |
- Fattibene, P, et al.
(författare)
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The 4th international comparison on EPR dosimetry with tooth enamel Part 1: Report on the results
- 2011
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Ingår i: Radiation Measurements. - : Elsevier. - 1350-4487 .- 1879-0925. ; 46:9, s. 765-771
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the results of the 4th International Comparison of in vitro electron paramagnetic resonance dosimetry with tooth enamel, where the performance parameters of tooth enamel dosimetry methods were compared among sixteen laboratories from all over the world. The participating laboratories were asked to determine a calibration curve with a set of tooth enamel powder samples provided by the organizers. Nine molar teeth extracted following medical indication from German donors and collected between 1997 and 2007 were prepared and irradiated at the Helmholtz Zentrum Munchen. Five out of six samples were irradiated at 0.1, 0.2, 0.5, 1.0 and 1.5 Gy air kerma; and one unirradiated sample was kept as control. The doses delivered to the individual samples were unknown to the participants, who were asked to measure each sample nine times, and to report the EPR signal response, the mass of aliquots measured, and the parameters of EPR signal acquisition and signal evaluation. Critical dose and detection limit were calculated by the organizers on the basis of the calibration-curve parameters obtained at every laboratory. For calibration curves obtained by measuring every calibration sample three times, the mean value of the detection limit was 205 mGy, ranging from 56 to 649 mGy. The participants were also invited to provide the signal response and the nominal dose of their current dose calibration curve (wherever available), the critical dose and detection limit of which were also calculated by the organizers.
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| 8. |
- Geber, Therese, et al.
(författare)
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Desiccants for retrospective dosimetry using optically stimulated luminescence (OSL)
- 2015
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Ingår i: Radiation Measurements. - : Elsevier BV. - 1879-0925 .- 1350-4487. ; 78, s. 17-22
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Tidskriftsartikel (refereegranskat)abstract
- Optically stimulated luminescence (OSL) was used to test different kinds of desiccants for their potential use in retrospective dosimetry. Desiccants are used for the purpose of absorbing liquids and can be found in a number of items which may be found in the immediate environment of a person, including hand bags, drug packages, and the vehicles of rescue service teams. Any material exhibiting OSL properties suitable for retrospective dosimetry is a useful addition to the existing dosimetry system available in emergency preparedness. Eleven kinds of desiccants were investigated in order to obtain an overview of the fundamental OSL properties necessary for retrospective dosimetry. Measurements were made using a Rise TL/OSL reader and irradiations were achieved with the Sr-90/Y-90 source incorporated in the reader. Several of the desiccants exhibited promising properties as retrospective dosemeters. Some of the materials exhibited a strong as-received signal, i.e. without any laboratory irradiation, but the origin of this signal has not yet been established. The minimum detectable dose ranged from 8 to 450 mGy for ten of the materials and for one material (consisting of natural clay) the minimum detectable dose was 1.8 Gy.
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| 9. |
- Geber, Therese, et al.
(författare)
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Eye lens dosimetry for interventional procedures - Relation between the absorbed dose to the lens and dose at measurement positions
- 2011
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Ingår i: Radiation Measurements. - : Elsevier BV. - 1350-4487 .- 1879-0925. ; 46:11, s. 1248-1251
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Konferensbidrag (refereegranskat)abstract
- This study investigated the relationship between the absorbed dose to the lens of the eye and the absorbed dose at different measurement positions near the eye of interventional radiologists. It also visualised the dose distribution inside the head, both when protective eyewear were used and without such protection. The best position for an eye lens dosimeter was found to be at the side of the head nearest to the radiation source, close to the eye. Positioning the dosimeter at the eyebrow could lead to an underestimation of the lens dose of as much as 45%. The measured dose distribution showed that the absorbed dose to the eye lenses was high compared to the other parts of the head, which stresses the importance of wearing protective eyewear. However, many models of eyewear were found to be deficient as the radiation could slip through at several places, e.g. at the cheek. The relationship between the absorbed dose to the lens and the kerma-area-product (P-KA) delivered to the patient was also studied. (C) 2011 Elsevier Ltd. All rights reserved.
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| 10. |
- Giussani, Augusto, et al.
(författare)
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Training activities on radiation protection in nuclear medicine in the frame of the EURATOM FP7 collaborative project MADEIRA
- 2011
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Ingår i: Radiation Measurements. - : Elsevier BV. - 1879-0925 .- 1350-4487. ; 46:11, s. 1310-1314
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Konferensbidrag (refereegranskat)abstract
- MADEIRA was a Collaborative Project cofunded by the European Commission through the EURATOM Seventh Research Framework Programme. It was structured into four scientific work packages, and its aim was to optimize the efficacy and safety of 3D functional imaging in nuclear medicine and thereby to reduce the radiation exposures of the patients while keeping or even improving the quality of the diagnostic information. Additionally, a fifth work package was dedicated to training and dissemination activities, including the organization of specific training courses, as well as research exchange programs for young scientists. This manuscript summarizes the experience gained during the Training Courses, in particular the one devoted to aspects of radiation protection in nuclear medicine. (C) 2011 Elsevier Ltd. All rights reserved.
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