| 1. |
- Adolfsson, Annsofie, 1960-, et al.
(författare)
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Miscarriage : Evidence Based Information for the Web and Its Development Procedure
- 2015
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Ingår i: Advances in Sexual Medicine. - Irvine, USA : Scientific Research Publishing. - 2164-5191 .- 2164-5205. ; 5:4, s. 89-110
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The aim of this paper is to describe the process of developing web information on miscarriage based on scientific evidence, for women and couples in Sweden experiencing miscarriage. Method: A participatory design was used which included researchers, professional xperts and users. A participatory design was used involving researchers, professional experts and users. The information was developed in six stages: 1) identifying the needs of information; 2) identifying and constructing the main areas of information and its paths; 3) identifying and inviting experts for revision; 4) developing the text; 5) reviewing the text; 6) design and structuring for adaption to website. Results: The text of information developed gradually based on the seven steps. The final text comprised three parts: 1) what is miscarriage; 2) experiences of miscarriage; 3) processing and lanning for new pregnancy. Conclusion: Using participatory design was time and resource consuming, however it was functional for producing appropriate information for the target group. The developed evidence based facts text is assumed to be a complement to the information that is provided by the health care system.
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| 2. |
- Adolfsson, Emelie, et al.
(författare)
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A system for remote dosimetry audit of 3D-CRT, IMRT and VMAT based on lithium formate dosimetry
- 2014
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Ingår i: Radiotherapy and Oncology. - : Elsevier. - 0167-8140 .- 1879-0887. ; 113:2, s. 279-282
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this work was to develop and test a remote end-to-end audit system using lithium formate EPR dosimeters. Four clinics were included in a pilot study, absorbed doses determined in the PTV agreed with TPS calculated doses within ±5% for 3D-CRT and ±7% (k=1) for IMRT/VMAT dose plans.
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| 3. |
- Adolfsson, Emelie, et al.
(författare)
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END-TO-END AUDIT: COMPARISON OF TLD AND LITHIUM FORMATE EPR DOSIMETRY
- 2019
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Ingår i: Radiation Protection Dosimetry. - : OXFORD UNIV PRESS. - 0144-8420 .- 1742-3406. ; 186:1, s. 119-122
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to test two different solid state dosimetry systems for the purpose of end-to-end audits of radiotherapy volumetric modulated arc therapy (VMAT) technique; a lithium formate electron paramagnetic resonance system and a lithium fluoride thermoluminescent dosimetry system. As a complement to the solid state systems, ion chamber measurements were performed. A polystyrene phantom with a planning target volume (PTV) and an organ at risk (OAR) structure was scanned using CT. A VMAT dose plan was optimized to deliver 2 Gy to the target volume and to minimize the dose to the OAR. The different detectors were inserted into the phantom and the planned dose distribution was delivered. The measured doses were compared to the treatment planning system (TPS) calculated doses. Good agreement was found between the TPS calculated and the measured doses, well accepted for the dose determinations in remote dosimetry audits of VMAT treatment technique.
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| 4. |
- Adolfsson, Emelie, et al.
(författare)
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Implementing empowerment group education in diabetes
- 2004
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Ingår i: Patient Education and Counseling. - : Elsevier BV. - 0738-3991 .- 1873-5134. ; 53:3, s. 319-324
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Forskningsöversikt (refereegranskat)abstract
- The overall aim was to gain insight into and understand how physicians and nurses view the implementation of empowerment group education (EGE) in diabetes. Prior to the study the physicians and nurses attended a 2-day empowerment workshop. Further, they had implemented the empowerment approach in two groups of patients with type II diabetes. Three to 9 months later they (five physicians and 11 nurses from six family practices) participated in focus group interviews to evaluate the implementation of the EGE. The interviews were audio-taped, transcribed and analysed using the constant comparative method. The main result showed a conflict in roles. The physicians and nurses knew their role in the traditional approach but not with respect to the empowerment approach, which they needed to grow into. At the same time as they started a new way of working, their role had changed from being an expert to being a facilitator. As experts they felt secure, as facilitators they needed support in their educational process. To implement EGE they required support both from the family practice and from a supervisor in direct connection with the EGE. © 2004 Elsevier Ireland Ltd. All rights reserved.
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| 5. |
- Adolfsson, Emelie, et al.
(författare)
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Investigation of signal fading in lithium formate EPR dosimeters using a new sensitive method
- 2012
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Ingår i: Physics in Medicine and Biology. - : Institute of Physics (IOP). - 0031-9155 .- 1361-6560. ; 57:8, s. 2209-2217
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate signal fading in lithium formate electron paramagnetic resonance (EPR) dosimeters used for clinical applications in radiotherapy. A new experimental method for determination of signal fading, designed to resolve small changes in signal from slowly decaying unstable radicals, was used. Possible signal fading in lithium formate due to different storage temperatures was also tested. Air humidity was kept at a constant level of 33% throughout the experiments. The conclusion drawn from the investigations was that the EPR signal from lithium formate is stable during at least 1 month after irradiation and is not sensitive to variations in storage temperature andlt;40 degrees C when kept at a relative air humidity of 33%. This makes lithium formate a suitable dosimeter for transfer dosimetry in clinical audits.
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| 6. |
- Adolfsson, Emelie, 1985-
(författare)
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Lithium formate EPR dosimetry for accurate measurements of absorbed dose in radiotherapy
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Lithium formate has shown to be a material with properties suitable for electron paramagnetic resonance (EPR) dosimetry, among them up to 7 times higher sensitivity compared to alanine, which is a well-established EPR detector material for dose determinations in radiotherapy.The aim of this thesis was to further investigate the properties of lithium formate and develop the dosimetry system towards applications in radiotherapy. The intrinsic efficiency for energies of relevance to brachytherapy and the signal stability were investigated. The dosimetry system was expanded to include a smaller dosimeter model, suitable for measurements in dose gradient regions. An individual sensitivity correction method was applied to the smaller dosimeters to be able to perform dose determinations with the same precision as for the larger ones. EPR dosimetry in general is time consuming and effort was spent to optimize the signal readout procedure regarding measurement time and measurement precision.The system was applied in two clinical applications chosen for their high demands on the dosimetry system: 1) a dosimetry audit for external photon beam therapy and 2) dose verification measurements around a low energy HDR brachytherapy source.The conclusions drawn from this thesis were: dose determinations can be performed with a standard uncertainty of 1.8-2.5% using both the original size dosimeters and the new developed smaller ones. The dosimetry system is robust and useful for applications when high measurement precision and accuracy is prioritized. It is a good candidate for dosimetry audits, both in external beam therapy and brachytherapy.
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| 7. |
- Adolfsson, Emelie, et al.
(författare)
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Measurement of absorbed dose to water around an electronic brachytherapy source : Comparison of two dosimetry systems: lithium formate EPR dosimeters and radiochromic EBT2 film
- 2015
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Ingår i: Physics in Medicine and Biology. - : Institute of Physics Publishing (IOPP). - 0031-9155 .- 1361-6560. ; 60:9, s. 3869-3882
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Tidskriftsartikel (refereegranskat)abstract
- Interest in high dose rate (HDR) electronic brachytherapy operating at 50 kV is increasing. For quality assurance it is important to identify dosimetry systems that can measure the absorbed doses in absolute terms which is difficult in this energy region. In this work a comparison is made between two dosimetry systems, EPR lithium formate dosimeters and radiochromic EBT2 film.Both types of dosimeters were irradiated simultaneously in a PMMA phantom using the Axxent EBS. Absorbed dose to water was determined at distances of 10 mm, 30 mm and 50 mm from the EBS. Results were traceable to different primary standards as regards to absorbed dose to water (EPR) and air kerma (EBT2). Monte Carlo simulations were used in absolute terms as a third estimate of absorbed dose to water.Agreement within the estimated expanded (k = 2) uncertainties (5% (EPR), 7% (EBT2)) was found between the results at 30 mm and 50 mm from the x-ray source. The same result was obtained in 4 repetitions of irradiation, indicating high precision in the measurements with both systems. At all distances, agreement between EPR and Monte Carlo simulations was shown as was also the case for the film measurements at 30mm and 50mm. At 10mm the geometry for the film measurements caused too large uncertainty in measured values depending on the exact position (within sub-mm distances) of the EBS and the 10 mm film results were exculded from comparison.This work has demonstrated good performance of the lithium formate EPR dosimetry system in accordance with earlier experiments at higher photon energies (192Ir HDR brachytherapy). It was also highlighted that there might be issues regarding the energy dependence and intrinsic efficiency of the EBT2 film that need to be considered for measurements using low energy sources.
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| 8. |
- 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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| 9. |
- Adolfsson, Emelie, 1985-, et al.
(författare)
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Response of Lithium Formate EPR Dosimeters at Photon Energies Relelvant to Brachytherapy
- 2009
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Ingår i: IFMBE Proceedings. - Heidelberg : Springer Berlin Heidelberg. - 9783642034725 - 9783642034749 ; , s. 236-239
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- After development of sensitive dosimeter materials Electron Paramagnetic Resonance EPR dosimetry has been successfully used also in radiation therapy. The intensity of the EPR-signal is a measure of the amount of free radicals created by ionizing radiation which is proportional to the absorbed dose in the dosimeter. Lithium formate monohydrate is a dosimeter material with 2-6 times higher sensitivity than alanine, a linear dose response over a wide dose range and mass-energy absorption properties similar to water. These properties make lithium formate promising for verification of absorbed doses around high dose rate brachytherapy sources where the dose gradient is steep and the photon energy distribution changing with distance from the source. Calibration of the dosimeters is performed in 60Co or MV photon beams where high dosimetric accuracy is feasible. The use in brachytherapy field relies on the assumption that the production of free radicals per mean absorbed dose in the dosimeter is similar at the lower photon energies present there. The aim of this work was to test that assumption. The response of the dosimeters as a function of photon energy was determined by irradiations with four x-ray qualities in the range 100-250 kV and 137Cs, relative to the response when irradiated with 60Co, all photon beams with well-known air kerma rates at the Swedish Secondary Standards Dosimetry Laboratory. Monte Carlo simulations were used to convert air kerma free in air to mean absorbed dose to the dosimeter. The measured response relative 60Co as a function of photon energy was below unity for all qualities. The maximum deviation from unity was 2.5% (100 kV, 135 kV) with a relative standard deviation of 1.5% (k = 1).
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| 10. |
- Adolfsson, Emelie, et al.
(författare)
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Response of lithium formate EPR dosimeters at photon energies relevant to the dosimetry of brachytherapy
- 2010
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Ingår i: Medical physics (Lancaster). - : American Association of Physicists in Medicine. - 0094-2405. ; 37:9, s. 4946-4959
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE:To investigate experimentally the energy dependence of the detector response of lithium formate EPR dosimeters for photon energies below 1 MeV relative to that at 60Co energies. High energy photon beams are used in calibrating dosimeters for use in brachytherapy since the absorbed dose to water can be determined with high accuracy in such beams using calibrated ion chambers and standard dosimetry protocols. In addition to any differences in mass-energy absorption properties between water and detector, variations in radiation yield (detector response) with radiation quality, caused by differences in the density of ionization in the energy imparted (LET), may exist. Knowledge of an eventual deviation in detector response with photon energy is important for attaining high accuracy in measured brachytherapy dose distributions.METHODS:Lithium formate EPR dosimeters were irradiated to known levels of air kerma in 25-250 kV x-ray beams and in 137Cs and 60Co beams at the Swedish Secondary Standards Dosimetry Laboratory. Conversions from air kerma free in air into values of mean absorbed dose to the detectors were made using EGSnrc MC simulations and x-ray energy spectra measured or calculated for the actual beams. The signals from the detectors were measured using EPR spectrometry. Detector response (the EPR signal per mean absorbed dose to the detector) relative to that for 60Co was determined for each beam quality.RESULTS:Significant decreases in the relative response ranging from 5% to 6% were seen for x-ray beams at tube voltages < or = 180 kV. No significant reduction in the relative response was seen for 137Cs and 250 kV x rays.CONCLUSIONS:When calibrated in 60Co or MV photon beams, corrections for the photon energy dependence of detector response are needed to achieve the highest accuracy when using lithium formate EPR dosimeters for measuring absorbed doses around brachytherapy sources emitting photons in the energy range of 20-150 keV such as 169Yb and electronic sources.
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| 11. |
- Costa, Tatiana, et al.
(författare)
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CHARACTERIZATION OF A LITHIUM FORMATE EPR-DOSIMETRY SYSTEM FOR PROTON RADIATION THERAPY
- 2019
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Ingår i: Radiation Protection Dosimetry. - : OXFORD UNIV PRESS. - 0144-8420 .- 1742-3406. ; 186:1, s. 83-87
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Tidskriftsartikel (refereegranskat)abstract
- The specific aim for the characterization of the lithium formate dosimetry system is to determine response and stability in a proton beam. The long-term goal for this investigation is an audit system for proton therapy like the end-to-end dose determinations performed for radiotherapy with photons. For a 150-MeV proton beam, the dose response was found to be linear in the dose interval 0-8.8 Gy. The accuracy of dose reconstruction was controlled in a blind test, in which the dose of 6.63 Gy was measured in samples irradiated with a real dose of 6.70 Gy. The stability was determined by irradiations of sets of four dosimeters every week during 1 month and analyzed at the same day thereafter. The fitting of the fading curve was done with a second-order polynomial resulting in a 6.6% lower value compared to the reference after 31 d.
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| 12. |
- 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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| 13. |
- Hultberg, Jonas, et al.
(författare)
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In-depth immune profiling reveals advanced B- and T-cell differentiation to be associated with Th1-driven immune dysregulation in common variable immunodeficiency
- 2023
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Ingår i: Clinical Immunology. - : ACADEMIC PRESS INC ELSEVIER SCIENCE. - 1521-6616 .- 1521-7035. ; 257
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Tidskriftsartikel (refereegranskat)abstract
- Common variable immunodeficiency (CVID) is an inborn error of immunity characterized by low levels of an-tibodies. In addition to infections, many patients also suffer from T-helper 1-driven immune dysregulation, which is associated with increased mortality. The aim of this study was to perform in-depth characterization of the T and the B cell compartments in a well-defined cohort of patients affected by CVID and correlate the findings to the level of clinical immune dysregulation. We used mass cytometry, targeted proteomics, flow cytometry and functional assays to delineate the immunological phenotype of 15 CVID-affected patients with different levels of immune dysregulation. Unbiased clustering of T cell mass cytometry data correlated with CVID-related immune dysregulation and plasma protein profiles. Expanded CXCR3+ T-bet-expressing B cells correlated with effector memory CD4+ T cell clusters, and increased plasma levels of CXCR3-ligands. Our findings indicate an interplay between B cells and T cells in CVID-related immune dysregulation and provide a better understanding of the underlying pathological mechanisms.
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| 14. |
- Kolbun, Natallia, et al.
(författare)
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High-resolution mapping of 1D and 2D dose distributions using X-band electron paramagnetic resonance imaging
- 2014
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press. - 0144-8420 .- 1742-3406. ; 159:1-4, s. 182-187
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Tidskriftsartikel (refereegranskat)abstract
- Electron paramagnetic resonance imaging (EPRI) was performed to visualise 2D dose distributions of homogenously irradiated potassium dithionate tablets and to demonstrate determination of 1D dose profiles along the height of the tablets. Mathematical correction was applied for each relative dose profile in order to take into account the inhomogeneous response of the resonator using X-band EPRI. The dose profiles are presented with the spatial resolution of 0.6 mm from the acquired 2D images; this value is limited by pixel size, and 1D dose profiles from 1D imaging with spatial resolution of 0.3 mm limited by the intrinsic line-width of potassium dithionate. In this paper, dose profiles from 2D reconstructed electron paramagnetic resonance (EPR) images using the Xepr software package by Bruker are focussed. The conclusion is that using potassium dithionate, the resolution 0.3 mm is sufficient for mapping steep dose gradients if the dosemeters are covering only +/- 2 mm around the centre of the resonator.
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| 15. |
- Ljusberg, Anna, et al.
(författare)
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Radiation-dependent demyelination in normal appearing white matter in glioma patients, determined using quantitative magnetic resonance imaging
- 2023
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Ingår i: Physics and Imaging in Radiation Oncology. - : ELSEVIER. - 2405-6316. ; 27
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Tidskriftsartikel (refereegranskat)abstract
- Background and purpose: A brain tumour, especially a glioma, is a rare disease; it is challenging to treat and the prognosis is often poor. Routine care includes surgery and concomitant chemoradiotherapy (CRT). Diagnostic work-up and treatment effects are typically evaluated using magnetic resonance imaging (MRI). Quantitative MRI (qMRI), unlike conventional MRI, has the advantage of providing tissue-specific relaxation rates and proton density. The purpose is to detect changes in normal appearing white matter (NAWM) in brain tumour patients after CRT using qMRI.Materials & methods: NAWM was analysed in 10 patients, in 83 MR examinations performed before and after surgery and after CRT. Relaxation rates R-1 and R-2, the proton density (PD) and the concentration of myelin (c(My)) were calculated from the qMRI scans and analysed in correlation to radiation dose and time after treatment.Results: A significant decrease in c(My) between pre-treatment imaging and first follow-up and an increase in PD were observed. For low doses (less than 30 Gy) PD and c(My) returned to baseline (=pre-operative status), while for high doses (>30 Gy) the change increased during the full extent of the follow-up period. No difference could be established for R-1. For R-2 an increase was observed during the first year, which then gradually returned to baseline. For R-2, stronger effects were seen as a consequence of higher absorbed doses. Conclusion: In the long-term follow-up for glioma patients, qMRI is a powerful tool for detecting small changes, such as a decrease of myelin concentration, in NAWM after CRT.
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| 16. |
- Lund, Eva, et al.
(författare)
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EPR imaging of dose distributions aiming at applications in radiation therapy
- 2014
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press. - 0144-8420 .- 1742-3406. ; 159:1-4, s. 130-136
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Tidskriftsartikel (refereegranskat)abstract
- A one-dimensional electron paramagnetic resonance (EPR) imaging method for visualisation of dose distributions in photon fields has been developed. Pressed pellets of potassium dithionate were homogeneously irradiated in a Co-60 radiation field to 600 Gy. The EPR analysis was performed with an X-Band (9.6 GHz) Bruker E540 EPR and EPR imaging spectrometer equipped with an E540 GC2X two-axis X-band gradient coil set with gradients along the y axis (along the sample tube) and z axis (along B-0) and an ER 4108TMHS resonator. Image reconstruction, including deconvolution, baseline corrections and corrections for the resonator sensitivity, was performed using an in-house-developed Matlab code for the purpose to have a transparent and complete algorithm for image reconstruction. With this method, it is possible to visualise a dose distribution with an accuracy of similar to 5 % within +/- 5 mm from the centre of the resonator.
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| 17. |
- Wesolowska, Paulina, et al.
(författare)
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Testing the methodology for a dosimetric end-to-end audit of IMRT/VMAT: results of IAEA multicentre and national studies
- 2019
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Ingår i: Acta Oncologica. - : TAYLOR & FRANCIS LTD. - 0284-186X .- 1651-226X. ; 58:12, s. 1731-1739
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Within an International Atomic Energy Agency (IAEA) co-ordinated research project (CRP), a remote end-to-end dosimetric quality audit for intensity modulated radiation therapy (IMRT)/ volumetric arc therapy (VMAT) was developed to verify the radiotherapy chain including imaging, treatment planning and dose delivery. The methodology as well as the results obtained in a multicentre pilot study and national trial runs conducted in close cooperation with dosimetry audit networks (DANs) of IAEA Member States are presented. Material and methods: A solid polystyrene phantom containing a dosimetry insert with an irregular solid water planning target volume (PTV) and organ at risk (OAR) was designed for this audit. The insert can be preloaded with radiochromic film and four thermoluminescent dosimeters (TLDs). For the audit, radiotherapy centres were asked to scan the phantom, contour the structures, create an IMRT/VMAT treatment plan and irradiate the phantom. The dose prescription was to deliver 4 Gy to the PTV in two fractions and to limit the OAR dose to a maximum of 2.8 Gy. The TLD measured doses and film measured dose distributions were compared with the TPS calculations. Results: Sixteen hospitals from 13 countries and 64 hospitals from 6 countries participated in the multicenter pilot study and in the national runs, respectively. The TLD results for the PTV were all within +/- 5% acceptance limit for the multicentre pilot study, whereas for national runs, 17 participants failed to meet this criterion. All measured doses in the OAR were below the treatment planning constraint. The film analysis identified seven plans in national runs below the 90% passing rate gamma criteria. Conclusion: The results proved that the methodology of the IMRT/VMAT dosimetric end-to-end audit was feasible for its intended purpose, i.e., the phantom design and materials were suitable; the phantom was easy to use and it was robust enough for shipment. Most importantly the audit methodology was capable of identifying suboptimal IMRT/VMAT delivery.
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