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  • 1.
    Adolfsson, Emelie
    et al.
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Grindborg, Jan-Erik
    Statens Strålskyddsinstitut, Stockholm.
    Gustafsson, Håkan
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences.
    Lund, Eva
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences.
    Carlsson Tedgren, Åsa
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Response of Lithium Formate EPR Dosimeters at Photon Energies Relelvant to Brachytherapy2009In: IFMBE Proceedings, Heidelberg: Springer Berlin Heidelberg , 2009, p. 236-239Conference paper (Other academic)
    Abstract [en]

    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).

  • 2.
    Adolfsson, Emelie
    et al.
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Grindborg, Jan-Erik
    Swedish Radiation Safety Authority, Stockholm, Sweden .
    Gustafsson, Håkan
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences.
    Lund, Eva
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences.
    Carlsson Tedgren, Åsa
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics. Swedish Radiation Safety Authority, Stockholm, Sweden .
    Response of lithium formate EPR dosimeters at photon energies relevant to the dosimetry of brachytherapy2010In: Medical physics (Lancaster), ISSN 0094-2405, Vol. 37, no 9, p. 4946-4959Article in journal (Refereed)
    Abstract [en]

    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.

  • 3.
    Adolfsson, Emelie
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    Carlsson Tedgren, Åsa
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Gustafsson, Håkan
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Biomedical Engineering.
    Lund, Eva
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    Optimisation of an EPR dosimetry system for robust and high precision dosimetry2014In: Radiation Measurements, ISSN 1350-4487, E-ISSN 1879-0925, Vol. 70, p. 21-28Article in journal (Refereed)
    Abstract [en]

    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.

  • 4.
    Adolfsson, Emelie
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    Gustafsson, Håkan
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Biomedical Engineering.
    Lund, Eva
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Olsson, Sara
    Medical Physics and Technology, Växjö Central Hospital, Växjö, Sweden.
    Carlsson Tedgren, Åsa
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    A system for remote dosimetry audit of 3D-CRT, IMRT and VMAT based on lithium formate dosimetry2014In: Radiotherapy and Oncology, ISSN 0167-8140, E-ISSN 1879-0887, Vol. 113, no 2, p. 279-282Article in journal (Refereed)
    Abstract [en]

    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.

  • 5.
    Adolfsson, Emelie
    et al.
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences.
    Karlsson, Mattias
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Carlsson Tedgren, Åsa
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Swedish Radiation Safety Authority, Stockholm, Sweden .
    Lund, Eva
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences.
    Olsson, Sara
    Central Hospital Växjö, Sweden.
    Gustafsson, Håkan
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences.
    Investigation of signal fading in lithium formate EPR dosimeters using a new sensitive method2012In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 57, no 8, p. 2209-2217Article in journal (Refereed)
    Abstract [en]

    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.

  • 6.
    Adolfsson, Emelie
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    White, Shane
    Department of Radiation Oncology (MAASTRO), GROW – School for Oncology and Developmental Biology, Maastricht University Medical Center, The Netherlands.
    Landry, Guillaume
    Department of Radiation Oncology (MAASTRO), GROW – School for Oncology and Developmental Biology, Maastricht University Medical Center, The Netherlands.
    Lund, Eva
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    Gustafsson, Håkan
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Biomedical Engineering.
    Verhaegen, Frank
    Department of Radiation Oncology (MAASTRO), GROW – School for Oncology and Developmental Biology, Maastricht University Medical Center, The Netherlands.
    Reniers, Brigitte
    Department of Radiation Oncology (MAASTRO), GROW – School for Oncology and Developmental Biology, Maastricht University Medical Center, The Netherlands.
    Carlsson Tedgren, Åsa
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Measurement of absorbed dose to water around an electronic brachytherapy source: Comparison of two dosimetry systems: lithium formate EPR dosimeters and radiochromic EBT2 film2015In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 60, no 9, p. 3869-3882Article in journal (Refereed)
    Abstract [en]

    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.

  • 7.
    Antonovic, Laura
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    Gustafsson, Håkan
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Carlsson Tedgren, Åsa
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Evaluation of a lithium formate EPR dosimetry system for dose measurements around Ir-192 brachytherapy sources2009In: MEDICAL PHYSICS, ISSN 0094-2405, Vol. 36, no 6, p. 2236-2247Article in journal (Refereed)
    Abstract [en]

    A dosimetry system using lithium formate monohydrate (HCO2Li center dot H2O) as detector material and electron paramagnetic resonance (EPR) spectroscopy for readout has been used to measure absorbed dose distributions around clinical Ir-192 sources. Cylindrical tablets with diameter of 4.5 mm, height of 4.8 mm, and density of 1.26 g/cm(3) were manufactured. Homogeneity test and calibration of the dosimeters were performed in a 6 MV photon beam. Ir-192 irradiations were performed in a PMMA phantom using two different source models, the GammaMed Plus HDR and the microSelectron PDR-v1 model. Measured absorbed doses to water in the PMMA phantom were converted to the corresponding absorbed doses to water in water phantoms of dimensions used by the treatment planning systems (TPSs) using correction factors explicitly derived for this experiment. Experimentally determined absorbed doses agreed with the absorbed doses to water calculated by the TPS to within +/- 2.9%. Relative standard uncertainties in the experimentally determined absorbed doses were estimated to be within the range of 1.7%-1.3% depending on the radial distance from the source, the type of source (HDR or PDR), and the particular absorbed doses used. This work shows that a lithium formate dosimetry system is well suited for measurements of absorbed dose to water around clinical HDR and PDR Ir-192 sources. Being less energy dependent than the commonly used thermoluminescent lithium fluoride (LiF) dosimeters, lithium formate monohydrate dosimeters are well suited to measure absorbed doses in situations where the energy dependence cannot easily be accounted for such as in multiple-source irradiations to verify treatment plans. Their wide dynamic range and linear dose response over the dose interval of 0.2-1000 Gy make them suitable for measurements on sources of the strengths used in clinical applications. The dosimeter size needs, however, to be reduced for application to single-source dosimetry.

  • 8.
    Berg, Kirsti
    et al.
    Norwegian University of Science and Technology, Trondheim, Norway.
    Ericsson, Madelene
    Umeå University, Sweden.
    Lindgren, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology. Norwegian University of Science and Technology, Trondheim, Norway.
    Gustafsson, Håkan
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Biomedical Engineering.
    A High Precision Method for Quantitative Measurements of Reactive Oxygen Species in Frozen Biopsies2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 3Article in journal (Refereed)
    Abstract [en]

    Objective

    An electron paramagnetic resonance (EPR) technique using the spin probe cyclic hydroxylamine 1-hydroxy-3-methoxycarbonyl-2,2,5,5-tetr​amethylpyrrolidine(CMH) was introduced as a versatile method for high precision quantification of reactive oxygen species, including the superoxide radical in frozen biological samples such as cell suspensions, blood or biopsies.

    Materials and Methods

    Loss of measurement precision and accuracy due to variations in sample size and shape were minimized by assembling the sample in a well-defined volume. Measurement was carried out at low temperature (150 K) using a nitrogen flow Dewar. The signal intensity was measured from the EPR 1st derivative amplitude, and related to a sample, 3-carboxy-proxyl (CP•) with known spin concentration.

    Results

    The absolute spin concentration could be quantified with a precision and accuracy better than ±10 µM (k = 1). The spin concentration of samples stored at −80°C could be reproduced after 6 months of storage well within the same error estimate.

    Conclusion

    The absolute spin concentration in wet biological samples such as biopsies, water solutions and cell cultures could be quantified with higher precision and accuracy than normally achievable using common techniques such as flat cells, tissue cells and various capillary tubes. In addition; biological samples could be collected and stored for future incubation with spin probe, and also further stored up to at least six months before EPR analysis, without loss of signal intensity. This opens for the possibility to store and transport incubated biological samples with known accuracy of the spin concentration over time.

  • 9.
    Christensen, Michael
    et al.
    Aarhus Univ, Denmark.
    Schiffer, Tomas A.
    Uppsala Univ, Sweden.
    Gustafsson, Håkan
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Norrköping/Finspång.
    Palmelund Krag, Soren
    Aarhus Univ Hosp, Denmark.
    Norregaard, Rikke
    Aarhus Univ, Denmark.
    Palm, Fredrik
    Uppsala Univ, Sweden.
    Metformin attenuates renal medullary hypoxia in diabetic nephropathy through inhibition uncoupling protein-22019In: Diabetes/Metabolism Research Reviews, ISSN 1520-7552, E-ISSN 1520-7560, Vol. 35, no 2, article id e3091Article in journal (Refereed)
    Abstract [en]

    Background The purpose of the study is to examine the effect of metformin on oxygen metabolism and mitochondrial function in the kidney of an animal model of insulinopenic diabetes in order to isolate any renoprotective effect from any concomitant effect on blood glucose homeostasis. Methods Sprague-Dawley rats were injected with streptozotocin (STZ) (50 mg kg(-1)) and when stable started on metformin treatment (250 mg kg(-1)) in the drinking water. Rats were prepared for in vivo measurements 25 to 30 days after STZ injection, where renal function, including glomerular filtration rate and sodium transport, was estimated in anesthetized rats. Intrarenal oxygen tension was measured using oxygen sensors. Furthermore, mitochondrial function was assessed in mitochondria isolated from kidney cortex and medulla analysed by high-resolution respirometry, and superoxide production was evaluated using electron paramagnetic resonance. Results Insulinopenic rats chronically treated with metformin for 4 weeks displayed improved medullary tissue oxygen tension despite of no effect of metformin on blood glucose homeostasis. Metformin reduced UCP2-dependent LEAK and differentially affected medullary mitochondrial superoxide radical production in control and diabetic rats. Conclusions Metformin attenuates diabetes-induced renal medullary tissue hypoxia in an animal model of insulinopenic type 1 diabetes. The results suggest that the mechanistic pathway to attenuate the diabetes-induced medullary hypoxia is independent of blood glucose homeostasis and includes reduced UCP2-mediated mitochondrial proton LEAK.

  • 10.
    Danilczuk, M.
    et al.
    nstitute of Nuclear Chemistry and Technology, Warsaw, Poland.
    Gustafsson, Håkan
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Sastry, M. D.
    Lund, Eva
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Development of nickel-doped lithium formate as potential EPR dosimeter for low dose determination2007In: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, ISSN 1386-1425, Vol. 67, no 5, p. 1370-1373Article in journal (Refereed)
    Abstract [en]

    EPR dosimetry employing l-α-alanine has been in vogue during the past few years, due to its tissue equivalence and linear dose response. However, l-α-alanine dosimetry has been improved during the past years, the sensitivity of this material is still too low for clinical applications. Polycrystalline lithium formate doped with NiCl2 was therefore examined for radiation response in the dose range of clinical interest (<5 Gy) using CW EPR and pulse EPR techniques. At equal and moderate settings of microwave power and modulation amplitude lithium formate doped with 1.6 wt% of NiCl2 was almost four times more sensitive compared to l-α-alanine, which is the most common EPR dosimeter standard. It was shown that the nickel-doped lithium formate has an excellent radiation response with a low limit of the measurable dose, and a linear dose response in the range 1–5 Gy. The relaxation and power saturation studies showed that high microwave power can be applied during measurements to improve the sensitivity of this material as an EPR dosimeter. These results show that lithium formate doped with Ni(II) exhibits promising properties required for further development of an EPR dosimeter in the dose range typical for clinical dosimetry.

  • 11. Danilczuk, M.
    et al.
    Gustafsson, Håkan
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Sastry, M.D.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Lund, Eva
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Lund, Anders
    Linköping University, Department of Physics, Chemistry and Biology, Chemical Physics . Linköping University, The Institute of Technology.
    Ammonium Dithionate – a New Material for Highly Sensitive EPR Dosimetry2008In: Spectrochimica Acta Part A - Molecular and Biomolecular Spectroscopy, ISSN 1386-1425, E-ISSN 1873-3557, Vol. 69, no 1, p. 18-21Article in journal (Refereed)
    Abstract [en]

    Polycrystalline ammonium dithionate has been examined for its radiation response in the low dose range (< 5 Gy) using EPR technique. The •SO3- radical ion was detected as a single EPR line with a peak-to-peak derivative width of ca. 0.44 mT in irradiated samples and its intensity was found to vary linearly with dose. At equal and moderate settings of microwave power and modulation amplitude ammonium dithionate was at least 7 times more sensitive than L-alanine which is the most common EPR dosimeter standard. Pulse experiments were performed on the powder samples to obtain the longitudinal relaxation time. These and microwave saturation experiments served to indicate the optimal microwave power to be applied during measurements as an EPR dosimeter for best sensitivity of this material. It is thus claimed that ammonium dithionate has excellent potential to become an EPR dosimeter with a low limit of the measurable dose for cases where tissue equivalence is not required or can be corrected for.

  • 12.
    Fattibene, P
    et al.
    Ist Super Sanita.
    Wieser, A
    Helmholtz Zentrum Muenchen.
    Adolfsson, Emelie
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences.
    Benevides, L A
    USN.
    Brai, M
    University of Palermo.
    Callens, F
    University of Ghent.
    Chumak, V
    Research Centre Radiat Medical AMS.
    Ciesielski, B
    Medical University of Gdansk.
    Della Monaca, S
    Ist Super Sanita.
    Emerich, K
    Department Paediat Dentistry.
    Gustafsson, Håkan
    Linköping University, Department of Medical and Health Sciences, Radiology. Linköping University, Faculty of Health Sciences.
    Hirai, Y
    Radiat Effects Research Fdn.
    Hoshi, M
    Hiroshima University.
    Israelsson, Axel
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences.
    Ivannikov, A
    Medical Radiol Research Centre.
    Ivanov, D
    Institute Met Phys.
    Kaminska, J
    Medical University of Gdansk.
    Ke, Wu
    Beijing Institute Radiat Med.
    Lund, Eva
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences.
    Marrale, M
    University of Palermo.
    Martens, L
    University of Ghent.
    Miyazawa, C
    Ohu University.
    Nakamura, N
    Radiat Effects Research Fdn.
    Panzer, W
    Helmholtz Zentrum Muenchen.
    Pivovarov, S
    Institute Nucl Phys.
    A Reyes, R
    Uniformed Serv University of Health Science.
    Rodzi, M
    Hiroshima University.
    Romanyukha, A A
    USN.
    Rukhin, A
    Institute Nucl Phys.
    Sholom, S
    Research Centre Radiat Medical AMS.
    Skvortsov, V
    Medical Radiol Research Centre.
    Stepanenko, V
    Medical Radiol Research Centre.
    A Tarpan, M
    University of Ghent.
    Thierens, H
    University of Ghent.
    Toyoda, S
    Okayama University of Science.
    Trompier, F
    Institute Radioprotect and Surete Nucl.
    Verdi, E
    Helmholtz Zentrum Muenchen.
    Zhumadilov, K
    Hiroshima University.
    The 4th international comparison on EPR dosimetry with tooth enamel Part 1: Report on the results2011In: Radiation Measurements, ISSN 1350-4487, E-ISSN 1879-0925, Vol. 46, no 9, p. 765-771Article in journal (Refereed)
    Abstract [en]

    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.

  • 13.
    Fattibene, Paola
    et al.
    Istituto Superiore di Sanità, Rome, Italy.
    Trompier, Francois
    Institut de Radioprotection et de Sûreté Nucléaire, Fontenay-aux-Roses, France.
    Wieser, Albrecht
    Institute of Radiation Protection, Helmholtz Zentrum München - German Research Center for Environmental Health, Neuherberg, Germany.
    Brai, Maria
    Dipartimento di Fisica e Chimica, Università di Palermo, Viale Delle Scienze, Palermo, Italy.
    Ciesielski, Bartlomej
    Medical University of Gdansk, Gdańsk, Poland.
    De Angelis, Cinzia
    Istituto Superiore di Sanità, Rome, Italy.
    Della Monaca, Sara
    Istituto Superiore di Sanità, Rome, Italy.
    Garcia, Tristan
    CEA, LIST, Laboratoire National Henri Becquerel, Gif-sur-Yvette, France.
    Gustafsson, Håkan
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Biomedical Engineering.
    Hole, Eli Olag
    Department of Physics, University of Oslo (UiO), Oslo, Norway.
    Juniewicz, M.
    Medical University of Gdansk, Gdańsk, Poland.
    Krefft, K.
    Medical University of Gdansk, Gdańsk, Poland.
    Longo, Anna
    Dipartimento di Fisica e Chimica, Università di Palermo, Palermo, Italy.
    Leveque, Philippe
    Université Catholique de Louvain, Louvain, Belgium.
    Lund, Eva
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    Marrale, Maurizio
    Dipartimento di Fisica e Chimica, Università di Palermo, Palermo, Italy.
    Michalec, Barbara
    The Henryk Niewodniczański Institute of Nuclear Physics, Kraków, Poland.
    Mierzwinska, Gabriela
    The Henryk Niewodniczański Institute of Nuclear Physics, Kraków, Poland.
    Rao, J. L.
    Sri Venkateswara University, Tirupati, Andhra Pradesh, India.
    Romanyukha, Alexander A.
    Naval Dosimetry Center, US Navy, Bethesda, MD, USA.
    Tuner, Hasan
    Department of Physics, Faculty of Art and Science, Balikesir University, 10145, Cagis, Balıkesir, Turkey.
    EPR dosimetry intercomparison using smart phone touch screen glass2014In: Radiation and Environmental Biophysics, ISSN 0301-634X, E-ISSN 1432-2099, Vol. 53, no 2, p. 311-320Article in journal (Refereed)
    Abstract [en]

    This paper presents the results of an interlaboratory comparison of retrospective dosimetry using the electron paramagnetic resonance method. The test material used in this exercise was glass coming from the touch screens of smart phones that might be used as fortuitous dosimeters in a large-scale radiological incident. There were 13 participants to whom samples were dispatched, and 11 laboratories reported results. The participants received five calibration samples (0, 0.8, 2, 4, and 10 Gy) and four blindly irradiated samples (0, 0.9, 1.3, and 3.3 Gy). Participants were divided into two groups: for group A (formed by three participants), samples came from a homogeneous batch of glass and were stored in similar setting; for group B (formed by eight participants), samples came from different smart phones and stored in different settings of light and temperature. The calibration curves determined by the participants of group A had a small error and a critical level in the 0.37-0.40-Gy dose range, whereas the curves determined by the participants of group B were more scattered and led to a critical level in the 1.3-3.2-Gy dose range for six participants out of eight. Group A were able to assess the dose within 20 % for the lowest doses (< 1.5 Gy) and within 5 % for the highest doses. For group B, only the highest blind dose could be evaluated in a reliable way because of the high critical values involved. The results from group A are encouraging, whereas the results from group B suggest that the influence of environmental conditions and the intervariability of samples coming from different smart phones need to be further investigated. An alongside conclusion is that the protocol was easily transferred to participants making a network of laboratories in case of a mass casualty event potentially feasible.

  • 14.
    Franzén, Stephanie
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences.
    Pihl, Liselotte
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences.
    Khan, Nadeem
    Gustafsson, Håkan
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Norrköping/Finspång. Linköping University, Faculty of Medicine and Health Sciences.
    Palm, Fredrik
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences.
    Pronounced kidney hypoxia precedes albuminuria in type 1 diabetic mice2016In: American Journal of Physiology - Renal Physiology, ISSN 1931-857X, E-ISSN 1522-1466, Vol. 310, no 9, p. F807-F809Article in journal (Refereed)
    Abstract [en]

    Intrarenal tissue hypoxia has been proposed as a unifying mechanism for the development of chronic kidney disease, including diabetic nephropathy. However, hypoxia has to be present before the onset of kidney disease in order to be the causal mechanism. In order to establish if hypoxia precedes the onset of diabetic nephropathy, we implemented a minimally invasive electron paramagnetic resonance oximetry technique using implanted oxygen sensing probes for repetitive measurements of in vivo kidney tissue oxygen tensions in mice. Kidney cortex oxygen tensions were measured before and up to 15 days after the induction of insulinopenic diabetes in male mice and compared to normoglycemic controls. On day 16, urinary albumin excretions and conscious glomerular filtration rates were determined in order to define the temporal relationship between intrarenal hypoxia and disease development. Diabetic mice developed pronounced intrarenal hypoxia three days after the induction of diabetes, which persisted throughout the study period. On day 16, diabetic mice had glomerular hyperfiltration, but normal urinary albumin excretion. In conclusion, intrarenal tissue hypoxia in diabetes precedes albuminuria thereby being a plausible cause for the onset and progression of diabetic nephropathy.

  • 15.
    Franzén, Stephanie
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences.
    Pihl, Liselotte
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences.
    Khan, Nadeem
    Geisel School Med, NH USA.
    Palm, Fredrik
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Uppsala University, Uppsala, Sweden .
    Gustafsson, Håkan
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Biomedical Engineering.
    Repetitive Measurements of Intrarenal Oxygenation In Vivo Using L Band Electron Paramagnetic Resonance2014In: Advances in Experimental Medicine and Biology, ISSN 0065-2598, E-ISSN 2214-8019, Vol. 812, p. 135-141Article in journal (Refereed)
    Abstract [en]

    Intrarenal oxygenation is heterogeneous with oxygen levels normally being highest in the superficial cortex and lowest in the inner medulla. Reduced intrarenal oxygenation has been implied in the pathology of several kidney diseases. However, there is currently no method available to repetitively monitor regional renal oxygenation using minimally invasive procedures. We therefore evaluated implantable lithium phthalocyanine (LiPc) probes, which display a close correlation between EPR line width and oxygen availability. LiPc probes were implanted in the kidney cortex and medulla in the same mouse and sEPR spectra were acquired using a L band scanner during inhalation of air (21 % oxygen) or a mixture of air and nitrogen (10 % oxygen). In order to separate the signals from the two probes, a 1 G/cm gradient was applied and the signals were derived from 40 consecutive sweeps. Peak-to-peak comparison of the EPR line was used to convert the signal to an approximate oxygen tension in MATLAB. Kidney cortex as well as medullary oxygenation was stable over the 45 day period (cortex 56 +/- 7 mmHg and medulla 43 +/- 6 mmHg). However, 10 % oxygen inhalation significantly reduced oxygenation in both cortex (56 +/- 6 to 34 +/- 2 mmHg n = 15 p less than 0.05) and medulla (42 +/- 5 to 29 +/- 3 mmHg n = 7 p less than 0.05). In conclusion, L band EPR using LiPc probes implanted in discrete intrarenal structures can be used to repetitively monitor regional renal oxygenation. This minimally invasive method is especially well suited for conditions of reduced intrarenal oxygenation since this increases the signal intensity which facilitates the quantification of the EPR signal to absolute oxygenation values.

  • 16.
    Gustafsson, Håkan
    Linköping University, Department of Medicine and Health Sciences. Linköping University, Faculty of Health Sciences.
    Development of sensitive EPR dosimetry methods2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Electron paramagnetic resonance (EPR) dosimetry using the well established dosimeter material alanine is a generally accepted dosimetric method for measurements of high absorbed doses. Alanine EPR dosimetry is however not sensitive enough for high precision measurements of low (< 5 Gy) absorbed doses using reasonably measurement times and small dosimeters. It has therefore not been possible to fully exploit the benefits of EPR dosimetry for applications in radiation therapy.

    The aim of this thesis was to show that sensitive EPR dosimetry is a competitive method for applications in radiation therapy fulfilling the requirements of measurement precision. Our strategy for reaching this goal was to search for new, more sensitive, EPR dosimeter materials fulfilling the criteria of being tissue equivalent, having a high radical yield and having a narrow EPR spectrum suitable for dosimetry. The best materials were found among formates and dithionates. Doping with small amounts of metal ions and recrystallisation in D2O were tested to further increase the sensitivity. Four promising candidate materials were tested regarding radical stability and dose response and among them lithium formate was chosen for dosimetry in radiation therapy applications.

    A high precision EPR dosimetry method was developed using lithium formate. The method included the development of a production method for EPR dosimeters with very homogenous shape, mass and composition. A read-out process was developed with maximal measurement precision for reasonably short measurement times. The method also included a dosimeter quality control before actual dose measurements. Measurement accuracy was controlled for every new dosimeter batch.

    This high precision lithium formate EPR dosimetry method was evaluated for pretreatment verifications of intensity modulated radiation therapy (IMRT) treatment plans. The precision and accuracy was shown to be sufficient (< 5 %) for measurements of doses above 1.5 Gy using one single dosimeter and a measurement time of 15 minutes. The described evaluation is therefore a demonstration of the improved precision at low dose determinations that is available with our sensitive EPR dosimeter materials.

    While the EPR signal intensity is proportional to absorbed dose, the signal shape is in some cases dependent on the radiation quality. A new method is presented for simultaneous measurements of beam LET (linear energy transfer) and absorbed dose in heavy charged particle beams using potassium dithionate EPR dosimetry. The study shows that when irradiating a dosimeter with 35 MeV carbon ions, the ratio of the signal amplitudes from two radicals in potassium dithionate vary along the track indicating a dependence on linear energy transfer, LET. Potassium dithionate may therefore be a promising EPR dosimeter material for simultaneous measurements of absorbed dose and LET in heavy charged particle radiation fields.

    List of papers
    1. Ammonium formate, a compound for sensitive EPR dosimetry
    Open this publication in new window or tab >>Ammonium formate, a compound for sensitive EPR dosimetry
    2004 (English)In: Radiation Research, ISSN 0033-7587, Vol. 161, no 4, p. 464-470Article in journal (Refereed) Published
    Abstract [en]

    Alanine EPR dosimetry has been applied successfully when measuring intermediate and high radiation doses. Although the performance of alanine dosimetry is being improved, the sensitivity of the material is too low for a fast and simple low- dose determination. Here we present the results using ammonium formate as an EPR dosimeter material. Ammonium formate is seven times more sensitive than alanine, using spectrometer settings optimized for the latter. Deuterated ammonium formate is found to be more than eight times more sensitive than alanine. Analysis of signal stability with time shows that the ammonium formate signal is stable by 5 min after irradiation and that no change in signal intensity is found during 8 days. The atomic composition of ammonium formate is closer to that of tissue than alanine, and thus the energy dependence is smaller than that of alanine at photon energies below 200 keV. Power saturation studies indicate that the energy transfer between the spins and the lattice is fast in ammonium formate, which gives the possibility of using high microwave power without saturation to further increase the sensitivity. These results suggest that ammonium formate has some important properties required of an EPR dosimeter for applications in dosimetry in the dose range typical for radiation therapy.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-12959 (URN)10.1667/RR3142 (DOI)
    Available from: 2008-03-03 Created: 2008-03-03
    2. Radiation-induced radicals in lithium formate monohydrate (LiHCO2·H2O). EPR and ENDOR studies of X-irradiated crystal and polycrystalline samples
    Open this publication in new window or tab >>Radiation-induced radicals in lithium formate monohydrate (LiHCO2·H2O). EPR and ENDOR studies of X-irradiated crystal and polycrystalline samples
    Show others...
    2004 (English)In: PCCP : physical chemistry chemical physics, ISSN 1463-9076, Vol. 6, p. 3017-3022Article in journal (Refereed) Published
    Abstract [en]

    Single crystals and polycrystalline samples of lithium formate monohydrate (HCO2Li·H2O) were X-irradiated at 295 K and studied using X-band EPR, ENDOR, and ENDOR-induced EPR (EIE) spectroscopy at 200 or 295 K. Two different radical species were observed. The overall dominating species is the CO2 radical trapped in the crystal matrix at an orientation not very different from that of the parent CO2 fragment in the unirradiated matrix. The g- and 13C hyperfine coupling tensors of the CO2 radical were determined. The large linewidth (about 1.5 mT) of the polycrystalline EPR spectrum is due to extensive hyperfine couplings with lithium ions and protons in the environment. Four lithium couplings and four proton couplings associated with the CO2 radical were measured, and all couplings were assigned to specific matrix nuclei. The spectra yield evidence for a second radical in low relative abundance. One small lithium hyperfine interaction detected was ascribed to this radical. Spectral simulations of the EPR and ENDOR spectra support the conclusions made.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-12960 (URN)10.1039/b402846e (DOI)
    Available from: 2008-03-03 Created: 2008-03-03 Last updated: 2009-06-08
    3. Enhanced sensitivity of lithium dithionates doped with rhodium and nickel for EPR dosimetry
    Open this publication in new window or tab >>Enhanced sensitivity of lithium dithionates doped with rhodium and nickel for EPR dosimetry
    Show others...
    2005 (English)In: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, ISSN 1386-1425, Vol. 62, no 1-3, p. 614-620Article in journal (Refereed) Published
    Abstract [en]

    Electron paramagnetic resonance (EPR) studies of X-irradiated lithium dithionate, Li2S2O6·2H2O, doped with Ni and Rh have shown that these impurities enhance the yield of radicals formed by X-irradiation at room temperature. The signal in the doped samples, measured peak-to-peak of the single EPR derivative line attributed to the SO3 anion was about 3–4 times that of the pure lithium dithionate and more than 10 times stronger than the alanine signal. These impurities also shortened the spin-lattice relaxation time, T1, which gives the possibility to measure the doped samples at a higher microwave power. This implies that sensitivity could be further enhanced in the already sensitive EPR dosimeter material lithium dithionate.

    Keywords
    EPR dosimetry; Free radicals; Radiation; Radiation yield; Spin-lattice relaxation; Effect of dopants
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-12961 (URN)10.1016/j.saa.2005.01.024 (DOI)
    Available from: 2008-03-03 Created: 2008-03-03 Last updated: 2009-05-15
    4. Development of nickel-doped lithium formate as potential EPR dosimeter for low dose determination
    Open this publication in new window or tab >>Development of nickel-doped lithium formate as potential EPR dosimeter for low dose determination
    2007 (English)In: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, ISSN 1386-1425, Vol. 67, no 5, p. 1370-1373Article in journal (Refereed) Published
    Abstract [en]

    EPR dosimetry employing l-α-alanine has been in vogue during the past few years, due to its tissue equivalence and linear dose response. However, l-α-alanine dosimetry has been improved during the past years, the sensitivity of this material is still too low for clinical applications. Polycrystalline lithium formate doped with NiCl2 was therefore examined for radiation response in the dose range of clinical interest (<5 Gy) using CW EPR and pulse EPR techniques. At equal and moderate settings of microwave power and modulation amplitude lithium formate doped with 1.6 wt% of NiCl2 was almost four times more sensitive compared to l-α-alanine, which is the most common EPR dosimeter standard. It was shown that the nickel-doped lithium formate has an excellent radiation response with a low limit of the measurable dose, and a linear dose response in the range 1–5 Gy. The relaxation and power saturation studies showed that high microwave power can be applied during measurements to improve the sensitivity of this material as an EPR dosimeter. These results show that lithium formate doped with Ni(II) exhibits promising properties required for further development of an EPR dosimeter in the dose range typical for clinical dosimetry.

    Keywords
    EPR, EPR dosimetry, Lithium formate
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-12962 (URN)10.1016/j.saa.2006.10.026 (DOI)
    Available from: 2008-03-03 Created: 2008-03-03 Last updated: 2009-04-15
    5. Lithium formate EPR dosimetry for verifications of planned dose distrubutions prior to intensity modulated radiation therapy
    Open this publication in new window or tab >>Lithium formate EPR dosimetry for verifications of planned dose distrubutions prior to intensity modulated radiation therapy
    2008 (English)In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 53, no 17, p. 4667-4682Article in journal (Refereed) Published
    Abstract [en]

    The objective of the present investigation was to evaluate lithium formate electron paramagnetic resonance (EPR) dosimetry for measurement of dose distributions in phantoms prior to intensity-modulated radiation therapy (IMRT). Lithium formate monohydrate tablets were carefully prepared, and blind tests were performed in clinically relevant situations in order to determine the precision and accuracy of the method. Further experiments confirmed that within the accuracy of the current method, the dosimeter response was independent of beam energies and dose rates used for IMRT treatments. The method was applied to IMRT treatment plans, and the dose determinations were compared to ionization chamber measurements. The experiments showed that absorbed doses above 3 Gy could be measured with an uncertainty of less than 2.5% of the dose (coverage factor k = 1.96). Measurement time was about 15 min using a well-calibrated dosimeter batch. The conclusion drawn from the investigation was that lithium formate EPR dosimetry is a promising new tool for absorbed dose measurements in external beam radiation therapy, especially for doses above 3 Gy.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-12963 (URN)10.1088/0031-9155/53/17/014 (DOI)
    Available from: 2008-03-03 Created: 2008-03-03 Last updated: 2017-12-13
    6. Potassium dithionate EPR dosimetry for determination of absorbed dose and LET distributions in different radiation qualities
    Open this publication in new window or tab >>Potassium dithionate EPR dosimetry for determination of absorbed dose and LET distributions in different radiation qualities
    2011 (English)In: Radiation Measurements, ISSN 1350-4487, E-ISSN 1879-0925, Vol. 46, no 9, p. 936-940Article in journal (Refereed) Published
    Abstract [en]

    With an increasing interest in using protons and light ions for radiation therapy there is a need for possibilities to simultaneously determine both absorbed dose (D) and linear energy transfer, LET, (LΔ). Potassium dithionate (K2S2O6) tablets were irradiated in a conventional 6 MV linear accelerator photon beam and a N7+ beam (E = 33.5 MeV/u) respectively. The EPR spectrum of irradiated potassium dithionate is a narrow doublet consisting of two signals, R1 and R2, with different microwave power saturation properties. On the basis of identification in related substances by EPR and ENDOR, these two signals are assigned to two non-equivalent SO3 – radicals. Our experiments showed that the ratios of these two lines (R1/R2) were clearly connected to beam LET. Irrespective of the mechanistic details this investigation suggests a new method for measurement of absorbed dose and beam LET by using potassium dithionate EPR dosimetry.

    Place, publisher, year, edition, pages
    Elsevier, 2011
    Keywords
    EPR dosimetry; Linear energy transfer; LET; Charged particles
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-12964 (URN)10.1016/j.radmeas.2011.03.006 (DOI)000296039300039 ()
    Note
    Funding agencies|Swedish Cancer Society| 4276-B05-07XBC |Available from: 2008-03-03 Created: 2008-03-03 Last updated: 2017-12-13
  • 17.
    Gustafsson, Håkan
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Ahrén, Maria
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    Söderlind, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Córdoba Gallego, José M.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Käll, Per-Olov
    Linköping University, Department of Physics, Chemistry and Biology, Physical Chemistry. Linköping University, Faculty of Science & Engineering.
    Nordblad, Per
    Uppsala Universitet.
    Westlund, Per-Olof
    Umeå Universitet.
    Uvdal, Kajsa
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    Engström, Maria
    Linköping University, Department of Medical and Health Sciences, Radiology. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Health Sciences.
    Magnetic and Electron Spin Relaxation Properties of (GdxY1-x)2O3 (0 ≤ x ≤ 1) Nanoparticles Synthesized by the Combustion Method. Increased Electron Spin Relaxation Times with Increasing Yttrium Content2011In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 115, no 13, p. 5469-5477Article in journal (Refereed)
    Abstract [en]

    The performance of a magnetic resonance imaging contrast agent (CA) depends on several factors, including the relaxation times of the unpaired electrons in the CA. The electron spin relaxation time may be a key factor for the performance of new CAs, such as nanosized Gd2O3 particles. The aim of this work is, therefore, to study changes in the magnetic susceptibility and the electron spin relaxation time of paramagnetic Gd2O3 nanoparticles diluted with increasing amounts of diamagnetic Y2O3. Nanoparticles of (GdxY1-x)2O3 (0 e x e 1) were prepared by the combustion method and thoroughly characterized (by X-ray di.raction, transmission electron microscopy, thermogravimetry coupled with mass spectroscopy, photoelectron spectroscopy, Fourier transform infrared spectroscopy, and magnetic susceptibility measurements). Changes in the electron spin relaxation time were estimated by observations of the signal line width in electron paramagnetic resonance spectroscopy, and it was found that the line width was dependent on the concentration of yttrium, indicating that diamagnetic Y2O3 may increase the electron spin relaxation time of Gd2O3 nanoparticles.

  • 18.
    Gustafsson, Håkan
    et al.
    Linköping University, Department of Medical and Health Sciences, Radiology. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Berg, Kirsti
    Norwegian University of Science and Technology.
    Lindgren, Mikael
    Norwegian University of Science and Technology.
    Engström, Maria
    Linköping University, Department of Medical and Health Sciences, Radiology. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    De Muinck, Ebo
    Linköping University, Department of Medical and Health Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Zachrisson, Helene
    Linköping University, Department of Medical and Health Sciences, Clinical Physiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Fe(3+) Heterogeneity in Ex Vivo Carotid Atherosclerotic Plaques2011In: Free Radical Biology & Medicine, ISSN 0891-5849, E-ISSN 1873-4596, Vol. 51, no Suppl. 1, p. S40-S40Article in journal (Other academic)
    Abstract [en]

    n/a

  • 19.
    Gustafsson, Håkan
    et al.
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Danilczuk, M.
    Linköping University, The Institute of Technology.
    Sastry, M. D.
    Linköping University, The Institute of Technology.
    Lund, Anders
    Linköping University, Department of Physics, Chemistry and Biology, Chemical Physics . Linköping University, The Institute of Technology.
    Lund, Eva
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Enhanced sensitivity of lithium dithionates doped with rhodium and nickel for EPR dosimetry2005In: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, ISSN 1386-1425, Vol. 62, no 1-3, p. 614-620Article in journal (Refereed)
    Abstract [en]

    Electron paramagnetic resonance (EPR) studies of X-irradiated lithium dithionate, Li2S2O6·2H2O, doped with Ni and Rh have shown that these impurities enhance the yield of radicals formed by X-irradiation at room temperature. The signal in the doped samples, measured peak-to-peak of the single EPR derivative line attributed to the SO3 anion was about 3–4 times that of the pure lithium dithionate and more than 10 times stronger than the alanine signal. These impurities also shortened the spin-lattice relaxation time, T1, which gives the possibility to measure the doped samples at a higher microwave power. This implies that sensitivity could be further enhanced in the already sensitive EPR dosimeter material lithium dithionate.

  • 20.
    Gustafsson, Håkan
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Biomedical Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Hallbeck, Martin
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Pathology and Clinical Genetics.
    Lindgren, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology. Norwegian University of Science and Technology, Norway.
    Kolbun, Natallia
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Jonson, Maria
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Engström, Maria
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    de Muinck, Ebo
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Region Östergötland, Heart and Medicine Center, Department of Cardiology in Linköping.
    Zachrisson, Helene
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    Visualization of oxidative stress in ex vivo biopsies using electron paramagnetic resonance imaging2015In: Magnetic Resonance in Medicine, ISSN 0740-3194, E-ISSN 1522-2594, Vol. 73, no 4, p. 1682-1691Article in journal (Refereed)
    Abstract [en]

    PURPOSE: The purpose of this study was to develop an X-Band electron paramagnetic resonance imaging protocol for visualization of oxidative stress in biopsies.

    METHODS: The developed electron paramagnetic resonance imaging protocol was based on spin trapping with the cyclic hydroxylamine spin probe 1-hydroxy-3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine and X-Band EPR imaging. Computer software was developed for deconvolution and back-projection of the EPR image. A phantom containing radicals of known spatial characteristic was used for evaluation of the developed protocol. As a demonstration of the technique electron paramagnetic resonance imaging of oxidative stress was performed in six sections of atherosclerotic plaques. Histopathological analyses were performed on adjoining sections.

    RESULTS: The developed computer software for deconvolution and back-projection of the EPR images could accurately reproduce the shape of a phantom of known spatial distribution of radicals. The developed protocol could successfully be used to image oxidative stress in six sections of the three ex vivo atherosclerotic plaques.

    CONCLUSIONS: We have shown that oxidative stress can be imaged using a combination of spin trapping with the cyclic hydroxylamine spin probe cyclic hydroxylamine spin probe 1-hydroxy-3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine and X-Band EPR imaging. A thorough and systematic evaluation on different types of biopsies must be performed in the future to validate the proposed technique. Magn Reson Med, 2014.

  • 21.
    Gustafsson, Håkan
    et al.
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    Hallbeck, Martin
    Linköping University, Department of Clinical and Experimental Medicine, Division of Inflammation Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Clinical Pathology and Clinical Genetics.
    Norell, M.
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Health Sciences.
    Lindgren, Mikael
    Norwegian University of Science and Technology, Trondheim, Norway.
    Engström, Maria
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    Rosén, Anders
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Health Sciences.
    Zachrisson, Helene
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    Fe(III) distribution varies substantially within and between atherosclerotic plaques2014In: Magnetic Resonance in Medicine, ISSN 0740-3194, E-ISSN 1522-2594, Vol. 2, no 71, p. 885-892Article in journal (Refereed)
    Abstract [en]

    PURPOSE:

    Vulnerable atherosclerotic plaques are structurally weak and prone to rupture, presumably due to local oxidative stress. Redox active iron is linked to oxidative stress and the aim of this study was to investigate the distribution of Fe(III) in carotid plaques and its relation to vulnerability for rupture.

    METHODS:

    Atherosclerotic plaques from 10 patients (three asymptomatic and seven symptomatic) were investigated. Plaque vulnerability was classified using ultrasound and immunohistochemistry and correlated to Fe(III) measured by electron paramagnetic resonance spectroscopy.

    RESULTS:

    Large intra-plaque Fe(III) variations were found. Plaques from symptomatic patients had a higher Fe(III) concentration as compared with asymptomatic plaques (0.36 ± 0.21 vs. 0.06 ± 0.04 nmol Fe(III)/mg tissue, P < 0.05, in sections adjoining narrowest part of the plaques). All but one plaque from symptomatic patients showed signs of cap rupture. No plaque from asymptomatic patients showed signs of cap rupture. There was a significant increase in cap macrophages in plaques from symptomatic patients compared with asymptomatic patients (31 ± 11% vs. 2.3 ± 2.3%, P < 0.01).

    CONCLUSION:

    Fe(III) distribution varies substantially within atherosclerotic plaques. Plaques from symptomatic patients had significantly higher concentrations of Fe(III), signs of cap rupture and increased cap macrophage activity.

  • 22.
    Gustafsson, Håkan
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Norrköping/Finspång. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Kale, Ajay
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Otorhinolaryngology in Linköping.
    Dasu, Alexandru
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. The Skandion Clinic, Uppsala, Sweden.
    Lund, Anders
    Linköping University, Department of Physics, Chemistry and Biology, Chemical Physics. Linköping University, Faculty of Science & Engineering.
    Edqvist, Per-Henrik
    Uppsala University, Uppsala, Sweden.
    Roberg, Karin
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Otorhinolaryngology in Linköping.
    EPR oximetry of cetuximab-treated head-and-neck tumours in a mouse model2017In: Cell Biochemistry and Biophysics, ISSN 1085-9195, E-ISSN 1559-0283, Vol. 75, no 3-4, p. 299-309Article in journal (Refereed)
    Abstract [en]

    Head and neck squamous cell carcinoma (HNSCC) tumours are associated with high mortality despite advances in therapy. The monoclonal antibody cetuximab (Erbitux®) has been approved for the treatment of advanced HNSCC. However, only a subset of HNSC patients receiving cetuximab actually responds to treatment, underlining the need for a means to tailor treatments of individual patients. The aim of the present study was to investigate the effect of cetuximab treatment on tumour growth, on tumour partial oxygen pressure as measured by LiPc electron paramagnetic resonance oximetry and on the expression of proteins involved in tumour growth, metabolism and hypoxia. Two HNSCC cell lines, UT-SCC-2 and UT-SCC-14, were used to generate xenografts on female BALB/c (nu/nu) nude mice. Mice with xenografts were given three injections of intraperitoneal cetuximab or phosphate-buffered saline, and the tumour volume was recorded continuously. After treatment the tumour partial oxygen pressure was measured by LiPc electron paramagnetic resonance oximetry and the expression of epidermal growth factor receptor (EGFR), phosphorylated EGFR, Ki-67, MCT1, MCT4, GLUT1, CAIX and HIF-1α were investigated by immunohistochemistry. In xenografts from both cell lines (UT-SCC-2 and UT-SCC-14) cetuximab had effect on the tumour volume but the effect was more pronounced on UT-SCC-14 xenografts. A higher tumour oxygenation was measured in cetuximab-treated tumours from both cell lines compared to untreated controls. Immunocytochemical staining after cetuximab treatment shows a significantly decreased expression of EGFR, pEGFR, Ki67, CAIX and nuclear HIF-1α in UT-SCC-14 tumours compared to untreated controls. MCT1 and GLUT1 were significantly decreased in tumours from both cell lines but more pronounced in UT-SCC-14 tumours. Taken together, our results show that cetuximab treatment decreases the tumour growth and increases the tumour partial oxygen pressure of HNSCC xenografts. Furthermore we found a potential connection between the partial oxygen pressure of the tumours and the expression of proteins involved in tumour growth, metabolism and hypoxia.

  • 23.
    Gustafsson, Håkan
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Radiation Physics .
    Kruczala, Krzysztof
    Krakow, Polen.
    Lund, Eva
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Radiation Physics .
    Schlick, Shulamith
    Detroit, USA.
    Visualizing the dose distribution and linear energy transfer by ID and 2D ESR imaging: A potassium dithionate dosimeter irradiated with C6+ and N7+ ions2008In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 112, no 29, p. 8437-8442Article in journal (Refereed)
    Abstract [en]

    We report the application of one- and two-dimensional (1D and 2D) spectral-spatial electron spin resonance imaging (ESRI) for visualizing the dose distribution and linear energy transfer (LET) in a potassium dithionate, K 2S2O6 (PDT), dosimeter irradiated with the heavy ions C6+ and N7+. The ESR spectrum in the irradiated PDT consists of a superposition of two isotropic signals assigned to two ·SO3- radicals, R1 and R2, with no hyperfine splittings and slightly different g values. The ID ESRI profiles clearly indicate the spatial penetration of the beams and the location of the sharp maximum dose, the "Bragg peak", detected for each beam. The depth penetrations are different: ≈2.3 mm for C6+ and ≈1.8 mm for N7+ beams, ±0.1 mm, beyond these limits, no radicals were detected. 2D spectral-spatial ESRI images reflect both the dose distribution and the spatial dependence of the relative intensities of radicals R1 and R2, an effect that is assigned to the depth variation of the LET. This study has demonstrated that ESRI is a promising new method for dose and LET determination. Of particular interest are applications in the field of radiotherapy with heavy ions, because in this case the Bragg peak is pronounced and the dose can be focused at specific depths while the surrounding areas are protected. © 2008 American Chemical Society.

  • 24.
    Gustafsson, Håkan
    et al.
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Biomedical Engineering.
    Lund, Anders
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Hole, Eli O.
    Department of Physics, University of Oslo, Norway.
    Sagstuen, Einar
    Department of Physics, University of Oslo, Norway.
    SO3- radicals for EPR dosimetry: X- and Q band EPRstudy and LET dependency of crystalline potassium dithionate2013In: Radiation Measurements, ISSN 1350-4487, E-ISSN 1879-0925, Vol. 59, p. 123-128Article in journal (Refereed)
    Abstract [en]

    The structures of the free radicals formed by the irradiation of potassium dithionate (K 2S2O6) with 60Co g -rays and 14N7þ ions were investigated by EPR to further examine a recently proposed LET effect in this material. Two types of SO 3 radical ions were identified in X-irradiated single crystals by measurements at X- and Q bands. One of these (S1) exhibited 33S hyperfine couplings At ¼ 12.49, Ajj ¼ 15.60 mT, the other (S2) A t ¼ 11.29, Ajj ¼ 13.92 mT. The g-factors were nearly isotropic, gt ¼ 2.0010, gjj ¼ 2.0003; and g t ¼ 2.0026, gjj ¼ 2.0008, respectively. The 33S hyperfine coupling tensors and g-tensors were axially symmetric about the trigonal <c>-axis, coinciding with the direction of the SeS bonds of the two nonequivalent S 2O2 6 ions in the crystal. A model for the radiation damage was proposed in which the SO 3 radical ions retain the orientation of the SO 3 groups, aligned along the trigonal axis. The structure of a third main radical species (S3) with gt ¼ 2.0026, gjj ¼ 2.0052 could not be unambiguously assigned, due to undetected 33S features. The relative integrated intensities of S1, S2 and S3 depended on the radiation quality and were approximately estimated as 0.18: 0.65:0.17 for 60Co g-rays and 0.47: 0.38: 0.15 for 14N7þ ions. Additional weak lines on the low field side of the main signal were tentatively attributed to SO 2 radical ions. An even weaker strongly anisotropic pair of lines was attributed to SO 3 radical pairs separated by 0.93 e0.95 nm along the trigonal axis.

  • 25.
    Gustafsson, Håkan
    et al.
    Linköping University, Department of Medical and Health Sciences, Radiology. Linköping University, Faculty of Health Sciences.
    Lund, Anders
    Linköping University, Department of Physics, Chemistry and Biology, Chemical Physics. Linköping University, The Institute of Technology.
    Lund, Eva
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences.
    Potassium dithionate EPR dosimetry for determination of absorbed dose and LET distributions in different radiation qualities2011In: Radiation Measurements, ISSN 1350-4487, E-ISSN 1879-0925, Vol. 46, no 9, p. 936-940Article in journal (Refereed)
    Abstract [en]

    With an increasing interest in using protons and light ions for radiation therapy there is a need for possibilities to simultaneously determine both absorbed dose (D) and linear energy transfer, LET, (LΔ). Potassium dithionate (K2S2O6) tablets were irradiated in a conventional 6 MV linear accelerator photon beam and a N7+ beam (E = 33.5 MeV/u) respectively. The EPR spectrum of irradiated potassium dithionate is a narrow doublet consisting of two signals, R1 and R2, with different microwave power saturation properties. On the basis of identification in related substances by EPR and ENDOR, these two signals are assigned to two non-equivalent SO3 – radicals. Our experiments showed that the ratios of these two lines (R1/R2) were clearly connected to beam LET. Irrespective of the mechanistic details this investigation suggests a new method for measurement of absorbed dose and beam LET by using potassium dithionate EPR dosimetry.

  • 26.
    Gustafsson, Håkan
    et al.
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Lund, Eva
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Olsson, Sara
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Lithium formate EPR dosimetry for verifications of planned dose distrubutions prior to intensity modulated radiation therapy2008In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 53, no 17, p. 4667-4682Article in journal (Refereed)
    Abstract [en]

    The objective of the present investigation was to evaluate lithium formate electron paramagnetic resonance (EPR) dosimetry for measurement of dose distributions in phantoms prior to intensity-modulated radiation therapy (IMRT). Lithium formate monohydrate tablets were carefully prepared, and blind tests were performed in clinically relevant situations in order to determine the precision and accuracy of the method. Further experiments confirmed that within the accuracy of the current method, the dosimeter response was independent of beam energies and dose rates used for IMRT treatments. The method was applied to IMRT treatment plans, and the dose determinations were compared to ionization chamber measurements. The experiments showed that absorbed doses above 3 Gy could be measured with an uncertainty of less than 2.5% of the dose (coverage factor k = 1.96). Measurement time was about 15 min using a well-calibrated dosimeter batch. The conclusion drawn from the investigation was that lithium formate EPR dosimetry is a promising new tool for absorbed dose measurements in external beam radiation therapy, especially for doses above 3 Gy.

  • 27.
    Gustafsson, Håkan
    et al.
    Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, Department of Medical and Health Sciences, Radiology. Linköping University, Faculty of Health Sciences.
    Norell, M.
    Linköping University, Department of Medical and Health Sciences, Clinical Physiology. Linköping University, Faculty of Health Sciences.
    Lindgren, M.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Engström, Maria
    Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, Department of Medical and Health Sciences, Radiology. Linköping University, Faculty of Health Sciences.
    Rosén, A.
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences.
    Zachrisson, Helene
    Linköping University, Department of Medical and Health Sciences, Clinical Physiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Centre, Department of Clinical Physiology UHL.
    Is vulnerability for carotid plaque rupture related to intrinsic Fe (III) distribution2012Conference paper (Other academic)
    Abstract [en]

    Atherosclerotic plaques vulnerable for rupture are characterised by e.g., a large lipid pole, a high concentration of inflammatory cells and a thin fibrous cap. Recent research has showed that vulnerable plaques are structurally weaker and therefore more likely to rupture in response to physical forces; possible due to high local concentrations of macrophages and reactive oxygen species (ROS).  It is well known that redox active iron catalyses production of ROS and that the presence of Fe(III) is linked to ROS production. The aim of this study was to investigate the distribution of Fe(III) in carotid plaques.

  • 28.
    Gustafsson, Håkan
    et al.
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Olsson, Sara
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Lund, Anders
    Linköping University, Department of Physics, Chemistry and Biology, Chemical Physics . Linköping University, The Institute of Technology.
    Lund, Eva
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Ammonium formate, a compound for sensitive EPR dosimetry2004In: Radiation Research, ISSN 0033-7587, Vol. 161, no 4, p. 464-470Article in journal (Refereed)
    Abstract [en]

    Alanine EPR dosimetry has been applied successfully when measuring intermediate and high radiation doses. Although the performance of alanine dosimetry is being improved, the sensitivity of the material is too low for a fast and simple low- dose determination. Here we present the results using ammonium formate as an EPR dosimeter material. Ammonium formate is seven times more sensitive than alanine, using spectrometer settings optimized for the latter. Deuterated ammonium formate is found to be more than eight times more sensitive than alanine. Analysis of signal stability with time shows that the ammonium formate signal is stable by 5 min after irradiation and that no change in signal intensity is found during 8 days. The atomic composition of ammonium formate is closer to that of tissue than alanine, and thus the energy dependence is smaller than that of alanine at photon energies below 200 keV. Power saturation studies indicate that the energy transfer between the spins and the lattice is fast in ammonium formate, which gives the possibility of using high microwave power without saturation to further increase the sensitivity. These results suggest that ammonium formate has some important properties required of an EPR dosimeter for applications in dosimetry in the dose range typical for radiation therapy.

  • 29.
    Hedlund, Anna
    et al.
    Linköping University, Department of Medical and Health Sciences, Radiology. Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, Faculty of Health Sciences.
    Ahrén, Maria
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry . Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, The Institute of Technology.
    Gustafsson, Håkan
    Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, Department of Medical and Health Sciences, Radiology. Linköping University, Faculty of Health Sciences.
    Abrikossova, Natalia
    Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Warntjes, Marcel
    Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, Department of Medical and Health Sciences, Clinical Physiology. Linköping University, Faculty of Health Sciences.
    Jönsson, Jan-Ingvar
    Linköping University, Department of Clinical and Experimental Medicine, Experimental Hematology. Linköping University, Faculty of Health Sciences.
    Uvdal, Kajsa
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Engström, Maria
    Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, Department of Medical and Health Sciences, Radiology. Linköping University, Faculty of Health Sciences.
    Detection of Gd2O3 Nanoparticles in Hematopoietic Cells for MRI Contrast EnhancementManuscript (preprint) (Other academic)
    Abstract [en]

    As the utility of magnetic resonance imaging (MRI) broadens, the importance of having specific and efficient contrast agents increases and there has been a huge development in the fields of molecular imaging and intracellular markers.

    Previous studies have shown that gadolinium oxide (Gd2O3 ) nanoparticles generate higher relaxivity than currently available Gd chelates. The Gd2O3 nanoparticles are also promising for MRI cell tracking. The aim of the present work was to study cell labeling with Gd2O3 nanoparticles and to improve techniques for monitoring hematopoietic stem cell migration by MRI.

    We studied particle uptake in two cell lines; the hematopoietic progenitor cell line Ba/F3 and the monocytic cell line THP-1. Cells were incubated with Gd2O3 nanoparticles as well as superparamagnetic iron oxide particles (SPIOs) for comparison. In addition, it was investigated whether the transfection agent protamine sulfate increased the particle uptake. Treated cells were examined by microscopic techniques, MRI and analyzed for particle content.

    Results showed that particles were intracellular, however in Ba/F3 only sparsely. The relaxation times were shortened with increasing particle concentration. Overall relaxivities, r1 and r2 for Gd2O3 nanoparticles in all cell samples measured were 5.1 ± 0.3 and 14.9 ± 0.7 (s-1mM-1) respectively. Goodness of fit was 0.97 in both cases. Protamine sulfate treatment increased the uptake in both Ba/F3 cells and THP-1 cells.

    Viability of treated cells was not significantly decreased and thus, we conclude that the use of Gd2O3 nanoparticles is suitable for this type of cell labeling by means of detecting and monitoring hematopoietic cells.

  • 30.
    Hedlund, Anna
    et al.
    Linköping University, Department of Medical and Health Sciences, Radiology. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Health Sciences.
    Ahrén, Maria
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    Gustafsson, Håkan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Abrikossova, Natalia
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    Warntjes, Marcel
    Linköping University, Department of Medical and Health Sciences, Clinical Physiology. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Jönsson, Jan-Ivar
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Medical and Physiological Chemistry.
    Uvdal, Kajsa
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    Engström, Maria
    Linköping University, Department of Medical and Health Sciences, Radiology. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Health Sciences.
    Gd2O3 nanoparticles in hematopoietic cells for MRI contrast enhancement2011In: International journal of nano medicine, ISSN 1178-2013, Vol. 6, p. 3233-3240Article in journal (Refereed)
    Abstract [en]

    As the utility of magnetic resonance imaging (MRI) broadens, the importance of having specific and efficient contrast agents increases and in recent time there has been a huge development in the fields of molecular imaging and intracellular markers. Previous studies have shown that gadolinium oxide (Gd2O3) nanoparticles generate higher relaxivity than currently available Gd chelates: In addition, the Gd2O3 nanoparticles have promising properties for MRI cell tracking. The aim of the present work was to study cell labeling with Gd2O3 nanoparticles in hematopoietic cells and to improve techniques for monitoring hematopoietic stem cell migration by MRI. Particle uptake was studied in two cell lines: the hematopoietic progenitor cell line Ba/F3 and the monocytic cell line THP-1. Cells were incubated with Gd2O3 nanoparticles and it was investigated whether the transfection agent protamine sulfate increased the particle uptake. Treated cells were examined by electron microscopy and MRI, and analyzed for particle content by inductively coupled plasma sector field mass spectrometry. Results showed that particles were intracellular, however, sparsely in Ba/F3. The relaxation times were shortened with increasing particle concentration. Relaxivities, r1 and r2 at 1.5 T and 21°C, for Gd2O3 nanoparticles in different cell samples were 3.6–5.3 s-1 mM-1 and 9.6–17.2 s-1 mM-1, respectively. Protamine sulfate treatment increased the uptake in both Ba/F3 cells and THP-1 cells. However, the increased uptake did not increase the relaxation rate for THP-1 as for Ba/F3, probably due to aggregation and/or saturation effects. Viability of treated cells was not significantly decreased and thus, it was concluded that the use of Gd2O3 nanoparticles is suitable for this type of cell labeling by means of detecting and monitoring hematopoietic cells. In conclusion, Gd2O3 nanoparticles are a promising material to achieve positive intracellular MRI contrast; however, further particle development needs to be performed.

  • 31.
    Israelsson, Axel
    et al.
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences.
    Gustafsson, Håkan
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences.
    Lund, Eva
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences.
    Dose response of xylitol and sorbitol for EPR retrospective dosimetry with applications to chewing gum2013In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 154, no 2, p. 133-141Article in journal (Refereed)
    Abstract [en]

    The purpose of this investigation was to study the radiation-induced electron paramagnetic resonance signal in sweeteners xylitol and sorbitol for use in retrospective dosimetry. For both sweeteners and chewing gum, the signal changed at an interval of 1–84 d after irradiation with minimal changes after 4–8 d. A dependence on storage conditions was noticed and the exposure of the samples to light and humidity was therefore minimised. Both the xylitol and sorbitol signals showed linearity with dose in the measured dose interval, 0–20 Gy. The dose-response measurements for the chewing gum resulted in a decision threshold of 0.38 Gy and a detection limit of 0.78 Gy. A blind test illustrated the possibility of using chewing gums as a retrospective dosemeter with an uncertainty in the dose determination of 0.17 Gy (1 SD).

  • 32.
    Ivarsson, Magnus
    et al.
    Swedish Museum Nat Hist, Sweden; Swedish Museum Nat Hist, Sweden.
    Broman, Curt
    Stockholm University, Sweden.
    Gustafsson, Håkan
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Biomedical Engineering.
    Holm, Nils G.
    Stockholm University, Sweden.
    Biogenic Mn-Oxides in Subseafloor Basalts2015In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, no 6, p. e0128863-Article in journal (Refereed)
    Abstract [en]

    The deep biosphere of the subseafloor basalts is recognized as a major scientific frontier in disciplines like biology, geology, and oceanography. Recently, the presence of fungi in these environments has involved a change of view regarding diversity and ecology. Here, we describe fossilized fungal communities in vugs in subseafloor basalts from a depth of 936.65 metres below seafloor at the Detroit Seamount, Pacific Ocean. These fungal communities are closely associated with botryoidal Mn oxides composed of todorokite. Analyses of the Mn oxides by Electron Paramagnetic Resonance spectroscopy (EPR) indicate a biogenic signature. We suggest, based on mineralogical, morphological and EPR data, a biological origin of the botryoidal Mn oxides. Our results show that fungi are involved in Mn cycling at great depths in the seafloor and we introduce EPR as a means to easily identify biogenic Mn oxides in these environments.

  • 33.
    Kolbun, Natallia
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    Adolfsson, Emelie
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    Gustafsson, Håkan
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    Lund, Eva
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    High-resolution mapping of 1D and 2D dose distributions using X-band electron paramagnetic resonance imaging2014In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 159, no 1-4, p. 182-187Article in journal (Refereed)
    Abstract [en]

    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.

  • 34. Komaguchi, K
    et al.
    Matsubara, Y
    Shiotani, M
    Gustafsson, Håkan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radiation Physics.
    Lund, Eva
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radiation Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Lund, Anders
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Chemical Physics .
    An ESR and ENDOR study of irradiated 6Li-formate2007In: Spectrochimica Acta Part A - Molecular and Biomolecular Spectroscopy, ISSN 1386-1425, E-ISSN 1873-3557, Vol. 66, no 3, p. 754-760Article in journal (Refereed)
    Abstract [en]

    Lithium formate (6LiOOCH·H2O), 95% 6Li enrichment, combined with an exchange of crystallization water with D2O was investigated. The ESR spectrum of the radiation induced free radicals stable at room temperature consists of a singlet with a narrow line width, 0.92 mT. 6Li has smaller magnetic moment and nuclear spin, which resulted in the narrower line width accompanied with an increase in peak amplitude. In comparison with lithium formate with natural isotopic composition, 6Li (7.5%, I = 1) and 7Li (92.5%, I = 3/2), the sensitivity was increased by a factor of two. With optimised spectrometer settings 6Li formate had seven times higher sensitivity compared to alanine. Therefore this material is proposed as a dosimeter material in a dose range down to 0.1 Gy. The g and the 13C-hyperfine (hf) tensors of the CO2- radical anion, major paramagnetic products, were evaluated to be g = (2.0037, 1.9975, 2.0017), and A(13C) = (465.5, 447.5, 581.3) MHz for polycrystalline samples at room temperature. Furthermore, the 1H-hf and 6Li-hf tensors observed for the surroundings of CO2- by ENDOR technique were in fairly good agreement with DFT calculations. The CO2- radicals are found to be so stable that the formate is applicable to the ESR dosimetry, because of fully relaxing in a fully relaxed geometrical structure of the CO2- component and remaining tight binding with the surroundings after the H atom detachment from HCO2-. © 2006 Elsevier B.V. All rights reserved.

  • 35.
    Lilledahl, Magnus B.
    et al.
    Norwegian University of Science and Technoogy, Norway.
    Gustafsson, Håkan
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Region Östergötland, Center for Diagnostics, Department of Biomedical Engineering.
    Gunnar Ellingsen, Pal
    Norwegian University of Science and Technoogy, Norway.
    Zachrisson, Helene
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    Hallbeck, Martin
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Pathology and Clinical Genetics.
    Stenhjem Hagen, Vegard
    Norwegian University of Science and Technoogy, Norway.
    Kildemo, Morten
    Norwegian University of Science and Technoogy, Norway.
    Lindgren, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology. Norwegian University of Science and Technoogy, Norway.
    Combined imaging of oxidative stress and microscopic structure reveals new features in human atherosclerotic plaques2015In: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 20, no 2, p. 020503-Article in journal (Refereed)
    Abstract [en]

    Human atherosclerotic samples collected by carotid endarterectomy were investigated using electronic paramagnetic resonance imaging (EPRI) for visualization of reactive oxygen species, and nonlinear optical microscopy (NLOM) to study structural features. Regions of strong EPRI signal, indicating a higher concentration of reactive oxygen species and increased inflammation, were found to colocalize with regions dense in cholesterol crystals as revealed by NLOM.

  • 36.
    Lund, Anders
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Chemical Physics .
    Gustafsson, Håkan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Radiation Physics .
    Maruani, J.
    Laboratoire de Chimie Physique, UPMC and CNRS, 75005 Paris, France.
    Shiotani, M.
    Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, Higashi-Hiroshima 739-8527, Japan.
    Automatic fitting to 'powder' EPR spectra of coupled paramagnetic species employing Feynman's theorem2006In: Spectrochimica Acta Part A - Molecular and Biomolecular Spectroscopy, ISSN 1386-1425, E-ISSN 1873-3557, Vol. 63, no 4, p. 830-835Article in journal (Refereed)
    Abstract [en]

    A previous automatic fitting procedure of EPR spectra has been extended with the purpose to characterise coupled paramagnetic complexes in powders and frozen solutions. The theoretical EPR spectra were obtained by matrix diagonalization of a general spin Hamiltonian. A least-squares fitting procedure using analytical derivatives of the calculated spectrum with respect to the spectroscopic, fine structure, nuclear quadrupole, electron-electron, and hyperfine coupling tensors was used to refine those parameters. The powder spectra of matrix isolated CF3 and RCF2CF2 radicals, previously measured at low temperature, were reanalysed with this method. A theoretically modeled complex consisting of a Cu2+ ion, featuring an axially symmetric g-tensor and 63Cu hyperfine structure anisotropy, and a free radical located at different orientations, with respect to the symmetry axis of the Cu2+ ion, was examined in order to investigate the possibility to recover the magnetic parameters of the separate units and the magnetic couplings between them. © 2005 Elsevier B.V. All right reserved.

  • 37.
    Lund, Anders
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical Physics . Linköping University, The Institute of Technology.
    Olsson, Sara
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radio Physics.
    Bonora, M
    Lund, Eva
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radio Physics.
    Gustafsson, Håkan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radio Physics.
    New materials for ESR dosimetry2002In: Spectrochimica Acta Part A - Molecular and Biomolecular Spectroscopy, ISSN 1386-1425, E-ISSN 1873-3557, Vol. 58, no 6, p. 1301-1311Article in journal (Refereed)
    Abstract [en]

    New materials for electron spin resonance (ESR) dosimetry have been investigated with the aim to find systems more sensitive than L-alanine accepted as a standard for high dose determinations. Among the investigated systems ammonium tartrate, 2-methylalanine, salts of formic acids and dithionates have been found to be more sensitive than alanine by a factor 2-10. The lower limit applies to tissue equivalent materials, while much higher sensitivities were obtained with formates and dithionates containing heavier atoms. The increased sensitivity was mainly attributed to suitable ESR properties of the room temperature stable radicals as regards spectral shape (narrow lines, little or no hyperfine structure) and microwave saturation properties (short relaxation times). The radical structures have when necessary been clarified by ENDOR spectroscopy, while the saturation properties have been screened by pulsed ESR measurements.

  • 38.
    Lund, Eva
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    Adolfsson, Emelie
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    Kolbun, Natallia
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    Gustafsson, Håkan
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    EPR imaging of dose distributions aiming at applications in radiation therapy2014In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 159, no 1-4, p. 130-136Article in journal (Refereed)
    Abstract [en]

    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.

  • 39.
    Lund, Eva
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radiation Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Gustafsson, Håkan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radiation Physics.
    Danilczuk, M
    Sastry, M D
    Lund, Anders
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Chemical Physics .
    Vestad, T A
    Malinen, E
    Hole, E O
    Sagstuen, E
    Formates and dithionates: sensitive EPR-dosimeter materials for radiation therapy2005In: 6 th International symposium on ESR dosimetry and applications,2005, England: Pergamon Press , 2005, p. 317-Conference paper (Refereed)
  • 40.
    Lund, Eva
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radiation Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Gustafsson, Håkan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radiation Physics.
    Danilczuk, M
    Sastry, M
    Lund, Anders
    Linköping University, Department of Physics, Chemistry and Biology.
    Vestad, T-A
    Malinen, E
    Hole, E O
    Sagstuen, E
    Formates and dithionates: sensitive EPR dosimeter materialsfor radiation therapy2004In: Applied Radiation and Isotopes, ISSN 0969-8043, E-ISSN 1872-9800, Vol. 62, p. 317-324Article in journal (Refereed)
  • 41.
    Lund, Eva
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Department of Medicine and Care, Radiation Physics.
    Gustafsson, Håkan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Department of Medicine and Care, Radiation Physics.
    Danilczuk, M
    Sastry, MD
    Lund, Anders
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Chemical Physics .
    Compounds of Li-6 and natural Li for EPR dosimetry in photon/neutron mixed radiation fields2004In: Spectrochimica Acta Part A - Molecular and Biomolecular Spectroscopy, ISSN 1386-1425, E-ISSN 1873-3557, Vol. 60, no 6, p. 1319-1326Article in journal (Refereed)
    Abstract [en]

    Formates and dithionates of Li-6, enriched and Li-7 in natural composition of Li offer a possibility to measure the absorbed dose from photons and thermal neutrons in a mixed radiation field for instance at a boron neutron capture therapy (BNCT) facility. Tests with formates and dithionates of enriched 6Li and lithium compounds with natural composition have been performed at the BNCT facility at Studsvik, Sweden. Irradiations have been performed at 3 cm depth in a Perspex phantom in a fluence rate of thermal neutrons 1.8 x 10(9) n cm(-2) s(-1). The compounds were also irradiated in a pure X-ray field from a 4 MV linear accelerator at 5 cm depth in a phantom with accurately determined absorbed doses. The signal intensity and shape was investigated within 3 h after the irradiation. A single line spectrum attributed to the CO2- radical was observed after irradiation of lithium formate. An increase in line width occurring after neutron irradiation in comparison with photon irradiation of the Li-6 sample was attributed to dipolar broadening between CO2- radicals trapped in the tracks of the alpha particles. A spectrum due to the SO3- radical anion was observed after irradiation of lithium dithionate. The signal amplitude increased using the Li-6 in place of the Li with natural composition of isotopes, in studies with low energy X-ray irradiation. Due to the decreased line width, caused by the difference in g(N) and I between the isotopes, the sensitivity with Li-6 dithionate may be enhanced by an order of magnitude compared to alanine dosimetry. After comprehensive examination of the different combinations of compounds with different amounts of Li-6 and Li-7 regarding dosimetry, radiation chemistry and EPR properties these dosimeter material might be used for dose determinations at BNCT treatments and for biomedical experiments. Interesting properties of the radical formation might be visible due to the large difference in ionization density of neutrons compared to photons. (C) 2003 Elsevier B.V. All rights reserved.

  • 42.
    Lund, Eva
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Radiation Physics .
    Gustafsson, Håkan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Radiation Physics .
    Danilczuk, M
    Sastry, MD
    Lund, Anders
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Chemical Physics .
    Vestad, TA
    Malinen, E
    Hole, EO
    Sagstuen, E
    Formates and dithionates: sensitive EPR-dosimeter materials for radiation therapy2005In: Applied Radiation and Isotopes, ISSN 0969-8043, E-ISSN 1872-9800, Vol. 62, no 2, p. 317-324Article in journal (Refereed)
    Abstract [en]

    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.

  • 43.
    Lundqvist, Helen
    et al.
    Department of Molecular and Clinical Medicine Linköping University.
    Dånmark, Staffan
    Department of Neuroscience and Locomotion Linköping University.
    Johansson, Uno
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Experimental Pathology .
    Gustafsson, Håkan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Radiation Physics .
    Öllinger, Karin
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Experimental Pathology . Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Pathology and Clinical Genetics.
    Evaluation of electron spin resonance for studies of superoxide anion production by human neutrophils interacting with Staphylococcus aureus and Staphylococcus epidermidis.2008In: Journal of Biochemical and Biophysical Methods, ISSN 0165-022X, E-ISSN 1872-857X, Vol. 70, no 6, p. 1059-1065Article in journal (Refereed)
    Abstract [en]

    The present study evaluates electron spin resonance (ESR) and the spin trapper 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline-N-oxide (DEPMPO) for analysis of superoxide radical production by human neutrophils interacting with viable Staphylococcus aureus and Staphylococcus epidermidis bacteria. To avoid auto-activation due to interaction with glass surfaces, neutrophils were preincubated in plastic tubes until the peak response was reached, and then transferred to a quartz flat cell to record the ESR spectra. The time point for peak response was identified by parallel analysis of the bacteria-neutrophil interaction using luminol amplified chemiluminescence. We found detectable ESR spectra from neutrophils interacting with as few as five bacteria of the weak activating S. epidermidis per neutrophil. Addition of the NADPH oxidase inhibitor diphenylene iodonium totally abolished spectra. Catalase, DMSO or an iron chelator had no impact on the produced spectra and ionomycin, a selective activator of intracellular NADPH oxidase, gave significant ESR spectra. Taken together, our results indicate that DEPMPO is cell permeable and detects NADPH oxidase derived superoxide anions formed in phagosomes or released by human neutrophils phagocytosing viable S. aureus and S. epidermidis. The technique may be used as a sensitive tool to evaluate superoxide anion production in human neutrophils.

  • 44. Sastry, M
    et al.
    Gustafsson, Håkan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radiation Physics.
    Lund, Anders
    Linköping University, Department of Physics, Chemistry and Biology.
    Lund, Eva
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radiation Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    51V(n,β)52Cr reaction for neutron dosimetry: Development and assessment of a spectrophotometric method for determination of Cr in vanadium at sub ppm level2004In: Spectrochimica Acta Part A - Molecular and Biomolecular Spectroscopy, ISSN 1386-1425, E-ISSN 1873-3557, Vol. 60, no 10, p. 2363-2367Article in journal (Refereed)
    Abstract [en]

    With a view to monitoring the changes in coloration caused by the nuclear reaction 51V(n,β)52Cr in solution of vanadyl sulphate and using it for neutron dosimetry, electronic absorption spectra of vanadyl sulphate solutions were investigated at different concentrations of chromate impurity in micromolar range. It was observed that the presence of chromate enhances the absorptivity over a wide wavelength range serving essentially as a colouring agent for vanadium matrix, presumably due to charge transfer process. The absorbance at 380nm varied linearly over a wide concentration range. The limit of detection of chromate obtained is shown to be adequate for detecting neutron-induced chemical transmutation of vanadium to chromium under standard reactor conditions, when used with long path length cells. It was observed that the absorbance does not change on electron irradiation, suggesting that radiolytic effects due to beta decay, if any, do not interfere in the measurement of neutron-induced changes. In addition to its potential for neutron dosimetry, this is the first report of a simple and direct method of estimation of Cr in vanadium matrix at sub ppm level.

  • 45. Sastry, M.D.
    et al.
    Gustafsson, Håkan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Radiation Physics .
    Danilczuk, M.
    Lund, Anders
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Chemical Physics .
    Dynamical effects and ergodicity in the dipolar glass phase: Evidence from time-domain EPR and phase memory time studies of AsO44- in Rb1-x(NH4)xH2PO4 (x = 0,0.5,1)2006In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 18, no 17, p. 4265-4284Article in journal (Refereed)
    Abstract [en]

    Three-pulse electron spin echo envelope modulation (ESEEM), hyperfine sublevel correlation spectroscopy (HYSCORE) investigations and two-pulse electron spin echo (ESE) measurements of phase memory time TM, were carried out, in the 20-200 K temperature range, on an AsO44- paramagnetic probe stabilized in RbH2PO4 (RDP), NH4H2PO4 (ADP), and dipolar glass Rb0.5(NH4)0.5H2PO4 (RADP). The results obtained on ADP revealed hyperfine interaction of the probe ion with the 14N of the ammonium ion, the coupling constant satisfying the condition of 'cancellation' at a field of 480 mT. The ammonium ion was found to be in two different sites in ADP, which became indistinguishable on the formation of dipolar glass RADP. These results were confirmed by HYSCORE spectral measurements. The fast Fourier transform (FFT) spectra of three-pulse ESEEM decays have clearly revealed the interaction with protons in the bond both in ADP and RDP, and in RADP with an averaged coupling constant. The phase memory times in RADP exhibited strong temperature dependence and were found to be dependent on the nuclear spin quantum number mI of 75As. The temperature dependence of TM exhibited a well-defined maximum around 90 K, coinciding with the temperature of onset of 'freezing' in Rb0.5(NH4)0.5H2PO 4. This is symptomatic of dynamic fluctuations in the dipolar glass phase, with onset around 150 K, going through a maximum around 90 K and slowing down on further cooling. These results suggest that in RADP, a dynamical mechanism with progressive slowing down below 90 K is operative in the glass formation. This implies that the RADP system, with x = 0.5, exists in an ergodic relaxor (R)-state in the 20-200 K temperature range wherein every fluctuating monodomain can be viewed as statistically representative of the whole sample. © IOP Publishing Ltd.

  • 46.
    Schiffer, Tomas A.
    et al.
    Uppsala Univ, Sweden.
    Christensen, Michael
    Aarhus Univ, Denmark.
    Gustafsson, Håkan
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Norrköping/Finspång.
    Palm, Fredrik
    Uppsala Univ, Sweden.
    The effect of inactin on kidney mitochondrial function and production of reactive oxygen species2018In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 13, no 11, article id e0207728Article in journal (Refereed)
    Abstract [en]

    Inactin is a long lasting anesthetic agent commonly used in rat studies, but is also shown to exert physiological effects such as reducing renal blood flow, glomerular filtration rate and depressing tubular transport capacity. The effect of inactin on isolated kidney mitochondria is unknown and may be important when studying related topics in anaesthetized animals. The aim of this study was to determine whether inactin exerts effects on mitochondrial function and production of reactive oxygen species. Kidney mitochondrial function and production of reactive oxygen after acutely (5 min) or longer (1.5 hour) anesthetizing rats with inactin was evaluated using high-resolution respirometry. The results demonstrate that inactin significantly improves respiratory control ratio, inhibits complex I in the mitochondrial respiratory chain, reduce both unregulated proton leak and time dependently reduce the regulated proton leak via uncoupling protein-2 and adenine nucleotide translocase. Inactin also contributes to increased mitochondrial hydrogen peroxide production. In conclusion, inactin exerts persistent effects on mitochondrial function and these profound effects on mitochondrial function should to be considered when studying mitochondria isolated from animals anesthesized with inactin.

  • 47.
    Schiffer, Tomas
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Uppsala Univ, Sweden.
    Gustafsson, Håkan
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Norrköping/Finspång.
    Palm, Fredrik
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Norrköping/Finspång.
    Kidney outer medulla mitochondria are more efficient compared with cortex mitochondria as a strategy to sustain ATP production in a suboptimal environment2018In: American Journal of Physiology - Renal Physiology, ISSN 1931-857X, E-ISSN 1522-1466, Vol. 315, no 3, p. F677-F681Article in journal (Refereed)
    Abstract [en]

    The kidneys receive similar to 25% of cardiac output, which is a prerequisite to maintain sufficient glomerular filtration rate. However, both intrarenal regional renal blood flow and tissue oxygen levels are heterogeneous with decreasing levels in the inner part of the medulla. These differences, in combination with the heterogeneous metabolic activity of the different nephron segment located in the different parts of the kidney, may constitute a functional problem when challenged. The proximal tubule and the medullary thick ascending limb of Henle are considered to have the highest metabolic rate, which is related to the high mitochondria content needed to sustain sufficient ATP production from oxidative phosphorylation to support high electrolyte transport activity in these nephron segments. Interestingly, the cells located in kidney medulla function at the verge of hypoxia, and the mitochondria may have adapted to the surrounding environment. However, little is known about intrarenal differences in mitochondria function. We therefore investigated functional differences between mitochondria isolated from kidney cortex and medulla of healthy normoglycemic rats by using high-resolution respirometry. The results demonstrate that medullary mitochondria had a higher degree of coupling, are more efficient, and have higher oxygen affinity, which would make them more suitable to function in an environment with limited oxygen supply. Furthermore, these results support the hypothesis that mitochondria of medullary cells have adapted to the normal hypoxic in vivo situation as a strategy of sustaining ATP production in a suboptimal environment.

  • 48. Vestad, Tor Arne
    et al.
    Gustafsson, Håkan
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Lund, Anders
    Linköping University, Department of Physics, Chemistry and Biology, Chemical Physics . Linköping University, The Institute of Technology.
    Hole, Eli Olaug
    Sagstuen, Einar
    Radiation-induced radicals in lithium formate monohydrate (LiHCO2·H2O). EPR and ENDOR studies of X-irradiated crystal and polycrystalline samples2004In: PCCP : physical chemistry chemical physics, ISSN 1463-9076, Vol. 6, p. 3017-3022Article in journal (Refereed)
    Abstract [en]

    Single crystals and polycrystalline samples of lithium formate monohydrate (HCO2Li·H2O) were X-irradiated at 295 K and studied using X-band EPR, ENDOR, and ENDOR-induced EPR (EIE) spectroscopy at 200 or 295 K. Two different radical species were observed. The overall dominating species is the CO2 radical trapped in the crystal matrix at an orientation not very different from that of the parent CO2 fragment in the unirradiated matrix. The g- and 13C hyperfine coupling tensors of the CO2 radical were determined. The large linewidth (about 1.5 mT) of the polycrystalline EPR spectrum is due to extensive hyperfine couplings with lithium ions and protons in the environment. Four lithium couplings and four proton couplings associated with the CO2 radical were measured, and all couplings were assigned to specific matrix nuclei. The spectra yield evidence for a second radical in low relative abundance. One small lithium hyperfine interaction detected was ascribed to this radical. Spectral simulations of the EPR and ENDOR spectra support the conclusions made.

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