| 1. |
- Karlsson, Mikael, et al.
(författare)
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"Distributed proton radiation therapy"--a new concept for advanced competence support.
- 2006
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Ingår i: Acta oncologica (Stockholm, Sweden). - : Informa UK Limited. - 0284-186X .- 1651-226X. ; 45:8, s. 1094-101
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Tidskriftsartikel (refereegranskat)abstract
- The increased interest in high precision radiation therapy is to a large extent driven by the potential of modern imaging technology. The aim of this project was to analyse how an expensive proton facility best could support a multi-centre health care system. We have developed a model for distributed expert collaboration where all clinical experts will work close to their patients in regional centres. Patients who are candidates for proton therapy will be examined and dose-planned at their regional clinic, discussed in a fully information supported video conference and digitally made available at the proton treatment facility. The proton facility itself will be placed near a communication centre easily reached by all patients where they will be treated under full responsibility of their own physician at the home clinic. This concept has been analysed in detail both with respect to the overall functionality and with respect to possible weaknesses. It was found that the concept of distributed radiation therapy, as proposed here, will offer a stable clinical solution for advanced radiation therapy. It will support the spread of knowledge, serve as a fully developed backup system and the concept will further serve as an efficient base for clinical research.
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| 2. |
- Adliene, Diana, et al.
(författare)
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Assessment of the environmental contamination with long-lived radionuclides around an operating RBMK reactor station
- 2006
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Ingår i: Journal of Environmental Radioactivity. - : Elsevier BV. - 1879-1700 .- 0265-931X. ; 90:1, s. 68-77
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Tidskriftsartikel (refereegranskat)abstract
- The presence of man-made gamma emitting radionuclides in the region within 32 km radius of the Ignalina NPP/Lithuania has been investigated during the period 2001-2004, prior to the closure of the first 4 the two operating RBMK 1500-type reactors. Gamma spectrometric measurements of various terrestrial and aquatic plants as well as of soil samples showed moderate environmental contamination with the fission product Cs-137 and with the neutron activation products Co-60 and Mn-54. Traces of the activation products Zn-65 and Ag-110m were found in the nearest vicinity of the NPP. Activity concentrations were inhomogeneously distributed in the area of interest. Moss and algae samples showed the highest uptake of radionuclides. In addition to the gamma spectrometric measurements, the levels of C-14 were determined in the same bio-indicator samples using accelerator mass spectrometry. (c) 2006 Elsevier Ltd. All rights reserved.
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| 3. |
- Andersen, C. E., et al.
(författare)
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Medical proton dosimetry using radioluminescence from aluminium oxide crystals attached to optical-fiber cables
- 2007
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576 .- 0167-5087. ; 580:1, s. 466-468
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Tidskriftsartikel (refereegranskat)abstract
- The prime objective of this study is to investigate if radioluminescence (RL) from carbon-doped aluminum oxide (Al2O3:C) crystals potentially can be used for absorbed dose-rate measurements during proton radiotherapy. The RL from two separate (2 mg) Al2O3:C crystals attached to optical-fiber cables were recorded during irradiations in water in a 175 MeV clinical proton beam. The RL response for low-LET protons in the plateau region of the Bragg curve was found to closely resemble that observed for a clinical 6 MV X-ray beam. An identical response was found in the Bragg peak (where the dose-averaged LET is about 4 keV/mu m) for absorbed doses less than 0.3 Gy. For doses in the range of 0.3-3Gy, we observed a significant decrease in luminescence efficiency with LET. At 3 Gy, the luminescence efficiency was about 60% in the Bragg-peak region. The study implies that the RL-signal from Al2O3:C could potentially be suitable for medical proton dosimetry in the 0-0.3 Gy range even without any LET-dependent correction factors.
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| 4. |
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| 5. |
- Aznar, Marianne C., et al.
(författare)
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A Monte Carlo study of the energy dependence of Al2O3:C crystals for real-time in vivo dosimetry in mammography
- 2005
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 114:Nos 1-3, s. 444-449
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Tidskriftsartikel (refereegranskat)abstract
- In a previous experimental study, a novel method for in vivo dosimetry has been investigated, based on radioluminescence (RL) and optically stimulated luminescence (OSL). However, because of the large difference in atomic composition between the detector material and the breast tissue, relatively large energy dependence in low-energy X-ray beams can be expected. In the present work, the energy dependence of Al2O3:C crystals was modelled with the Monte Carlo code EGSnrc using three types of X-ray spectra. The results obtained (5.6-7.3%) agree with a previously determined experimental result (9%) within the combined standard uncertainty of the two methods. The influence of the size of the crystal on the energy dependence was investigated together with the effect of varying the thickness of the surrounding light-protective material. The results obtained indicate a minor effect owing to the thickness of the light-protective material, and a somewhat larger effect from reducing the diameter of the crystal. The outcome of this study can be used to improve the future design of the RL/OSL dosimetry system for use in mammography.
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| 6. |
- Aznar, MC, et al.
(författare)
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In vivo absorbed dose measurements in mammography using a new real-time luminescence technique
- 2005
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Ingår i: British Journal of Radiology. - : British Institute of Radiology. - 1748-880X .- 0007-1285. ; 78:928, s. 328-334
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Tidskriftsartikel (refereegranskat)abstract
- A dosimetry system based on radioluminescence (RL) and optically stimulated luminescence (OSL) from carbon doped aluminium oxide (Al2O3:C) crystals was developed for in vivo absorbed dose measurements in mammography. A small cylindrical crystal of Al2O3:C (diameter 0.48 mm and length 2 mm) was coupled to the end of a 1 mm diameter optical fibre cable. Owing to their small size and characteristic shape, these probes can be placed on the body surface in the field of view during the examination, without compromising the reading of the mammogram. Our new technique was tested with a mammography unit (Siemens Mammomat 3000) and screen-film technique over a range of clinically relevant X-ray energies. The results were compared with those obtained from an ionization chamber usually used for the determination of absorbed dose in mammography. The reproducibility of measurements was around 3% (1 standard deviation) at 4.5 mGy for both RL and OSL data. The dose response was found to be linear between 4.5 mGy and 30 mGy. The energy dependence of the system is around 18% between 23 kV and 35 kV. In vivo measurements were performed during three patient examinations. It was shown that entrance and exit doses could be measured. The presence of the small probes did not significantly interfere with the diagnostic quality of the images. Entrance doses estimated by RL/OSL results agreed within 3% with entrance surface dose values calculated from the ionization chamber measurements. These results indicate a considerable potential for use in routine control and in vivo dose measurements in mammography.
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| 7. |
- Bernhardsson, Christian, et al.
(författare)
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Household salt as a retrospective dosemeter using optically stimulated luminescence.
- 2009
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Ingår i: Radiation and Environmental Biophysics. - : Springer Science and Business Media LLC. - 1432-2099 .- 0301-634X. ; 48, s. 21-28
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this work was to investigate the potential of a selection of household salts (NaCl) as a retrospective dosemeter for ionising radiation using optically stimulated luminescence (OSL). The OSL-response of five brands of salt to an absorbed dose in the range from 1 mGy to 9 Gy was investigated using a Risø TL/OSL-15 reader and a (60)Co beam, allowing low dose-rate irradiations. The salt was optically stimulated with blue light (lambda = 470 +/- 30 nm) at a constant stimulation power (CW-OSL) of 20 mW cm(-2). A linear dose response relationship was found in the dose range from 1 mGy to about 100 mGy and above that level, the relationship becomes moderately supra-linear, at least up to 9 Gy. Depending on the sensitivity and background signal, the minimum detectable absorbed dose (MDD) for the household salt when kept at sealed conditions varied from 0.2 to 1.0 mGy, for the household salts investigated. In addition to its widespread abundance and availability, the low MDD suggests that household salt should seriously be considered as an emergency dosemeter. However, the OSL-properties of NaCl under normal household usage need to be more properly investigated as well as the variation in sensitivity by the quality of the radiation. A further optimisation of the read-out sequence for various brands of commercially available salt may further improve the sensitivity, in terms of luminescence yield, and the signal reproducibility.
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| 8. |
- Bernhardsson, Christian, et al.
(författare)
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OSL in Household Salt (NaCl) for Environmental, Occupational and Medical Dosimetry
- 2009
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Ingår i: Medical Physics In The Baltic States: Proceedings Of The 7th International Conference On Medical Physics. - 1822-5721. ; , s. 65-68
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Konferensbidrag (refereegranskat)abstract
- The recent progress in our work to implement salt (NaCl) as a dosemeter is presented. Laboratory investigations have indicated a linear dose response from 1 mGy to about 100 mGy and detection limits down to 0.1 mGy. Investigations in the clinic comparing TL-dosimetry in LiF and OSL in NaCl have indicated a similar dose response for the two dosemeters at different photon energies. Field studies with stationary dosemeter kits containing TLDs (LiF) and NaCl suggests that salt is also a good candidate for environmental monitoring of radiation.
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| 9. |
- Borjesson, Jimmy, et al.
(författare)
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Medical applications of X-ray fluorescence for trace element research
- 2007
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Ingår i: Powder Diffraction. - : Cambridge University Press (CUP). - 0885-7156 .- 1945-7413. ; 22:2, s. 130-137
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Tidskriftsartikel (refereegranskat)abstract
- Techniques for estimation of element levels directly in humans (noninvasive in vivo) or in samples (in vitro) from humans are reviewed. Toxic, nonessential, trace elements may cause temporary or permanent damage to various organs and tissues in humans. There is thus a need to control the concentrations. Knowledge of the relations between toxic effects and element concentration may be extracted from measurements in humans as well as in samples from humans and her environment. Applications traditionally include occupationally exposed subjects, but an increasing research area is studies of members of the general population and of patients undergoing therapy for malignant and other diseases. Most in vivo XRF studies deal with lead in bone and cadmium in kidneys. For retired lead workers, a clear association has been demonstrated between bone lead and blood lead, due to endogenous lead excretion from the skeleton. A study of mercury in vivo showed that the technique is capable of detecting mercury in heavily exposed worker's kidneys. In vivo XRF in cancer and rheumatology patients has helped to understand how platinum and gold are retained in the human body. The newest in vivo applications include zinc in prostate gland and arsenic in skin. (c) 2007 International Centre for Diffraction Data.
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| 10. |
- Båth, Magnus, 1974, et al.
(författare)
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Nodule detection in digital chest radiography: introduction to the RADIUS chest trial.
- 2005
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Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 114:1-3, s. 85-91
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Tidskriftsartikel (refereegranskat)abstract
- Most digital radiographic systems of today have wide latitude and are hence able to provide images with a small constraint on dose level. This opens up for an unprejudiced dose optimisation. However, in order to succeed in the optimisation task, good knowledge of the imaging and detection processes is needed. As a part of the European-wide research project 'unification of physical and clinical requirements for medical X-ray imaging'-governed by the Radiological Imaging Unification Strategies (RADIUS) Group-a major image quality trial was conducted by members of the group. The RADIUS chest trial was focused on the detection of lung nodules in digital chest radiography with the aims of determining to what extent (1) the detection of a nodule is dependent on its location, (2) the system noise disturbs the detection of lung nodules, (3) the anatomical noise disturbs the detection of lung nodules and (4) the image background and anatomical background act as pure noise for the detection of lung nodules. The purpose of the present paper is to give an introduction to the trial and describe the framework and set-up of the investigation.
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