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Sökning: L773:1742 3406 OR L773:0144 8420 > (2010-2014)

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1.
  • Abul-Kasim, Kasim (författare)
  • LOW-DOSE SPINE CT: OPTIMISATION AND CLINICAL IMPLEMENTATION.
  • 2010
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 139, s. 169-172
  • Tidskriftsartikel (refereegranskat)abstract
    • Spinal deformities affect young individuals predominantly girls who are usually subjected to regular and intensive radiological investigation especially before and after corrective surgery. Optimisation of spine computed tomography (CT) and the implementation of the low-dose CT in the work-up of spinal deformities were presented. The presented low-dose CT here means providing the operating surgeons with essential information about 15 vertebral bodies (almost 36-cm long region of the vertebral column). The mean effective dose of the low-dose CT was 0.37 mSv without any negative impact on image quality with regard to answering the clinical questions at issue. Tube current modulation (angular and longitudinal) has contributed to 19 % of the total dose reduction and soft tissue algorithm has helped to reduce the artefacts from the metal implants in the postoperative CTs.
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2.
  • Ainsbury, E A, et al. (författare)
  • REVIEW OF RETROSPECTIVE DOSIMETRY TECHNIQUES FOR EXTERNAL IONISING RADIATION EXPOSURES.
  • 2011
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 147:4, s. 573-592
  • Tidskriftsartikel (refereegranskat)abstract
    • The current focus on networking and mutual assistance in the management of radiation accidents or incidents has demonstrated the importance of a joined-up approach in physical and biological dosimetry. To this end, the European Radiation Dosimetry Working Group 10 on 'Retrospective Dosimetry' has been set up by individuals from a wide range of disciplines across Europe. Here, established and emerging dosimetry methods are reviewed, which can be used immediately and retrospectively following external ionising radiation exposure. Endpoints and assays include dicentrics, translocations, premature chromosome condensation, micronuclei, somatic mutations, gene expression, electron paramagnetic resonance, thermoluminescence, optically stimulated luminescence, neutron activation, haematology, protein biomarkers and analytical dose reconstruction. Individual characteristics of these techniques, their limitations and potential for further development are reviewed, and their usefulness in specific exposure scenarios is discussed. Whilst no single technique fulfils the criteria of an ideal dosemeter, an integrated approach using multiple techniques tailored to the exposure scenario can cover most requirements.
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3.
  • Andersson, Martin, et al. (författare)
  • An internal radiation dosimetry computer program, IDAC 2.0, for estimation of patient doses from radiopharmaceuticals
  • 2014
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 162:3, s. 299-305
  • Tidskriftsartikel (refereegranskat)abstract
    • The internal dosimetry computer program internal dose assessment by computer (IDAC) for calculations of absorbed doses to organs and tissues as well as effective doses to patients from examinations with radiopharmaceuticals has been developed. The new version, IDAC2.0, incorporates the International Commission on Radiation Protection (ICRP)/ICRU computational adult male and female voxel phantoms and decay data from the ICRP publication 107. Instead of only 25 source and target regions, calculation can now be made with 63 source regions to 73 target regions. The major advantage of having the new phantom is that the calculations of the effective doses can be made with the latest tissue weighting factors of ICRP publication 103. IDAC2.0 uses the ICRP human alimentary tract (HAT) model for orally administrated activity and for excretion through the gastrointestinal tract and effective doses have been recalculated for radiopharmaceuticals that are orally administered. The results of the program are consistent with published data using the same specific absorption fractions and also compared with published data from the same computational phantoms but with segmentation of organs leading to another set of specific absorption fractions. The effective dose is recalculated for all the 34 radiopharmaceuticals that are administered orally and has been published by the ICRP. Using the new HAT model, new tissue weighting factors and the new adult computational voxel phantoms lead to an average effective dose of half of its earlier estimated value. The reduction mainly depends on electron transport simulations to walled organs and the transition from the stylised phantom with unrealistic interorgan distances to more realistic voxel phantoms.
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4.
  • Aslund, Magnus, et al. (författare)
  • Detectors for the future of X-ray imaging
  • 2010
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 139:1-3, s. 327-333
  • Tidskriftsartikel (refereegranskat)abstract
    • In recent decades, developments in detectors for X-ray imaging have improved dose efficiency. This has been accomplished with for example, structured scintillators such as columnar CsI, or with direct detectors where the X rays are converted to electric charge carriers in a semiconductor. Scattered radiation remains a major noise source, and fairly inefficient anti-scatter grids are still a gold standard. Hence, any future development should include improved scatter rejection. In recent years, photon-counting detectors have generated significant interest by several companies as well as academic research groups. This method eliminates electronic noise, which is an advantage in low-dose applications. Moreover, energy-sensitive photon-counting detectors allow for further improvements by optimising the signal-to-quantum-noise ratio, anatomical background subtraction or quantitative analysis of object constituents. This paper reviews state-of-the-art photon-counting detectors, scatter control and their application in diagnostic X-ray medical imaging. In particular, spectral imaging with photon-counting detectors, pitfalls such as charge sharing and high rates and various proposals for mitigation are discussed.
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5.
  • Aurumskjöld, Marie-Louise, et al. (författare)
  • A PHANTOM STUDY SHOWING THE IMPORTANCE OF COMPRESSION IN CONVENTIONAL DIAGNOSTIC X-RAY EXAMINATIONS.
  • 2010
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; Apr 7, s. 78-80
  • Tidskriftsartikel (refereegranskat)abstract
    • Compression was earlier an important and well-managed part of the clinical routine, but during the past 15-20 y the use has diminished, except for mammography, where it is a prerequisite for having images of high quality and low radiation dose. According to national and European regulations and recommendations, it is important to apply the compression technique to obtain the optimal image quality and radiation dose in common conventional diagnostic examinations. Current experience of compression technique is, however, based on studies carried out a long time ago and with analogue imaging techniques. An anthropomorphic phantom was used to show the importance of compression in conventional X-ray examinations. The patient thicknesses on volunteers with and without compression was measured. This measurement was done to investigate compression potential on patients and to select suitable phantom thicknesses. The X-ray examinations that were included in the study were abdomen overview, lumbar spine and the pelvis. The results from the phantom study showed a large dependency of the kerma-area product value on the phantom thickness. The phantom study suggests that there is a potential for significant reduction of radiation dose to the patient by using compression also with modern X-ray techniques. A dose reduction of up to 50 % or even more may be obtained.
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6.
  • Baverstock, K, et al. (författare)
  • Can a system approach help radiobiology?
  • 2011
  • Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 143:2-4, s. 536-541
  • Tidskriftsartikel (refereegranskat)
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7.
  • Berner, Karin, et al. (författare)
  • Dose optimisation of double-contrast barium enema examinations.
  • 2010
  • Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 139:1-3, s. 388-392
  • Tidskriftsartikel (refereegranskat)abstract
    • The purpose of the present work was to optimise the filtration and dose setting for double-contrast barium enema examinations using a Philips MultiDiagnost Eleva FD system. A phantom study was performed prior to a patient study. A CDRAD phantom was used in a study where copper and aluminium filtration, different detector doses and tube potentials were examined. The image quality was evaluated using the software CDRAD Analyser and the phantom dose was determined using the Monte Carlo-based software PCXMC. The original setting [100 % detector dose (660 nGy air kerma) and a total filtration of 3.5 mm Al, at 81 kVp] and two other settings identified by the phantom study (100 % detector dose and additional filtration of 1 mm Al and 0.2 mm Cu as well as 80 % detector dose and added filtration of 1 mm Al and 0.2 mm Cu) were included in the patient study. The patient study included 60 patients and up to 8 images from each patient. Six radiologists performed a visual grading characteristics study to evaluate the image quality. A four-step scale was used to judge the fulfillment of three image quality criteria. No overall statistical significant difference in image quality was found between the three settings (P > 0.05). The decrease in the effective dose for the settings in the patient study was 15 % when filtration was added and 34 % when both filtrations was added and detector dose was reduced. The study indicates that additional filtration of 1 mm Al and 0.2 mm Cu and a decrease in detector dose by 20 % from the original setting can be used in colon examinations with Philips MultiDiagnost Eleva FD to reduce the patient dose by 30 % without significantly affecting the image quality. For 20 exposures, this corresponds to a decrease in the effective dose from 1.6 to 1.1 mSv.
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8.
  • Brehwens, Karl, et al. (författare)
  • A new device to expose cells to changing dose rates of ionising radiation
  • 2012
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press. - 0144-8420 .- 1742-3406. ; 148:3, s. 366-371
  • Tidskriftsartikel (refereegranskat)abstract
    • In many exposure scenarios to ionising radiation, the dose rate is not constant. Despite this, most in vitro studies aimed at investigating the effects of ionising radiation are carried out exposing samples at constant dose rates. Consequently, very little data exist on the biological effects of exposures to changing dose rates. This may be due to technical limitations of standard irradiation facilities, but also to the fact that the importance of research in this area has not been appreciated. We have recently shown that cells exposed to a decreasing dose rate suffer higher levels of cytogenetic damage than do cells exposed to an increasing or a constant dose rate. To further study the effects of changing dose rates, a new device was constructed that permits the exposure of cell samples in tubes, flasks or Petri dishes to changing dose rates of X-rays. This report presents the technical data, performance and dosimetry of this novel device.
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9.
  • Båth, Magnus, 1974, et al. (författare)
  • Effective dose to patients from chest examinations with tomosynthesis
  • 2010
  • Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 139:1-3, s. 153-158
  • Tidskriftsartikel (refereegranskat)abstract
    • Chest tomosynthesis, which refers to the principle of collecting low-dose projections of the chest at different angles and using these projections to reconstruct section images of the chest, is an imaging technique recently introduced to health care. The main purpose of the present work was to determine the average effective dose to patients from clinical use of chest tomosynthesis. Exposure data for two chest radiography laboratories with tomosynthesis option (Definium 8000 with VolumeRAD option, GE Healthcare, Chalfont St. Giles, UK) were registered for 20 patients with a weight between 60 and 80 kg (average weight of 70.2 kg). The recorded data were used in the Monte Carlo program PCXMC 2.0 (STUK-Radiation and Nuclear Safety Authority, Helsinki, Finland) to determine the average effective dose for each projection. The effective dose for the chest tomosynthesis examination, including a scout view and the tomosynthesis acquisition, was finally obtained by adding the effective doses from all projections. Using the weighting factors given in ICRP 103, the average effective dose for the examination was found to be 0.13 mSv, whereas the average effective dose for the conventional two-view chest radiography examination was 0.05 mSv. A conversion factor of 0.26 mSv Gy(-1) cm(-2) was found suitable for determining the effective dose from a VolumeRAD chest tomosynthesis examination from the total registered kerma-area product. In conclusion, the effective dose to a standard-sized patient (170 cm/70 kg) from a VolumeRAD chest tomosynthesis examination is ~2 % of an average chest CT and only two to three times the effective dose from the conventional two-view chest radiography examination.
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10.
  • Båth, Magnus, 1974 (författare)
  • Evaluating imaging systems: practical applications
  • 2010
  • Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 139:1-3, s. 26-36
  • Tidskriftsartikel (refereegranskat)abstract
    • There are many ways in which imaging systems can be evaluated. The aim of the present paper is to provide an overview of a number of selected approaches to evaluating imaging systems, often encountered by the medical physicist, and discuss their validity and reliability. Specifically, it will cover (i) characterisation of an imaging system in terms of its detective quantum efficiency using linear-systems analysis; (ii) attempts to calculate relevant measures directly in images using the Rose model and the pixel signal-to-noise ratio; (iii) task-based methods incorporating human observers such as receiver-operating characteristics and (iv) visual grading-based methods using experienced radiologists as observers.
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11.
  • Carlander, Anna, et al. (författare)
  • The effect of radiation dose reduction on clinical image quality in chest radiography of premature neonates using a dual-side readout technique computed radiography system
  • 2010
  • Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 139:1-3, s. 275-280
  • Tidskriftsartikel (refereegranskat)abstract
    • The purpose of the present study was to investigate if the exposure could be reduced from the clinical setting (resulting in an effective dose of 8 microSv for a neonate of weight 0.7 kg and height 25 cm at a tube voltage of 90 kV) without negatively influencing the image quality for a dual-side readout technique computed radiography (CR) system in chest radiography of premature neonates. Chest radiographs of premature neonates were acquired with the double-side readout technique CR system. The images underwent simulated dose reduction in steps of 20 % to represent five different radiation dose levels. Four image quality criteria, related to the visibility of important anatomical structures, were used in a visual grading study where five experienced radiologists rated how well the criteria were fulfilled for all images. When reducing the radiation dose, a decrease in image quality could be observed already at the 80 % dose level for all the structures. The results indicate that a decrease in exposure from the clinically used setting affects the image quality negatively for the CR system.
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12.
  • Christiansson, Maria, et al. (författare)
  • USING AN OPTIMISED OSL SINGLE-ALIQUOT REGENERATIVE-DOSE PROTOCOL FOR LOW-DOSE RETROSPECTIVE DOSIMETRY ON HOUSEHOLD SALT.
  • 2011
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 144, s. 584-587
  • Tidskriftsartikel (refereegranskat)abstract
    • The single-aliquot regenerative-dose (SAR) protocols used in retrospective dosimetry for optically stimulated luminescence measurements have been mainly developed for archaeological and geological dating of quartz and feldspar. The aim in this study is to find a read-out protocol that can generate the most reproducible signal for household salt (NaCl) at absorbed doses below 100 mGy. The relation between the reproducibility of the signal, in terms of the ratio between given absorbed dose and SAR-calculated dose, and parameters such as test-dose pre-heat temperature has been studied. It was found that a temperature of 200°C yielded the best reproducibility in the SAR-calculated dose, which is a somewhat higher pre-heat temperature than what is used for dating of quartz.
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13.
  • Christofides, Stelios, et al. (författare)
  • Introduction to suspension levels: nuclear medicine
  • 2013
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 153:2, s. 161-165
  • Tidskriftsartikel (refereegranskat)abstract
    • In 2007, the European Commission (EC) commissioned a group of experts to undertake the revision of Report Radiation Protection (RP) 91, written in 1997, on oCriteria for acceptability of radiological (including radiotherapy) and nuclear medicine installations'. The revised draft report was submitted to the EC. Before publication, the EC issued this document for public consultation and has commissioned the same group of experts to consider the comments of the public consultation in further improving the revised report. The EC intends to publish the final report under its Radiation Report Series with the number RP 162. This paper introduces the project and presents the methodology adopted to devise the criteria of acceptability/suspension levels for nuclear medicine equipment.
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14.
  • Eidemüller, Markus, et al. (författare)
  • Breast cancer risk after radiation treatment at infancy: potential consequences of radiation-induced genomic instability.
  • 2011
  • Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 143:2-4, s. 375-9
  • Tidskriftsartikel (refereegranskat)abstract
    • Swedish hemangioma patients were treated in infancy mainly by external application of radium-226 starting from 1920. This work analysed the radiation risk among 17,158 women with a total of 678 breast cancer incidence cases with models of carcinogenesis and empirical excess relative risk models. Models incorporating effects of genomic instability were developed and applied to the hemangioma cohort. The description of the radiation risk was significantly improved with a model of genomic instability at an early stage of carcinogenesis.
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15.
  • Eriksson, Ida, et al. (författare)
  • Determination of the detective quantum efficiency of gamma camera systems: a Monte Carlo study
  • 2010
  • Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 139:1-3, s. 219-227
  • Tidskriftsartikel (refereegranskat)abstract
    • The purpose of the present work was to investigate the validity of using the Monte Carlo technique for determining the detective quantum efficiency (DQE) of a gamma camera system and to use this technique in investigating the DQE behaviour of a gamma camera system and its dependency on a number of relevant parameters. The Monte Carlo-based software SIMIND, simulating a complete gamma camera system, was used in the present study. The modulation transfer function (MTF) of the system was determined from simulated images of a point source of (99m)Tc, positioned at different depths in a water phantom. Simulations were performed using different collimators and energy windows. The MTF of the system was combined with the photon yield and the sensitivity, obtained from the simulations, to form the frequency-dependent DQE of the system. As figure-of-merit (FOM), the integral of the 2D DQE was used. The simulated DQE curves agreed well with published data. As expected, there was a strong dependency of the shape and magnitude of the DQE curve on the collimator, energy window and imaging position. The highest FOM was obtained for a lower energy threshold of 127 keV for objects close to the detector and 131 keV for objects deeper in the phantom, supporting an asymmetric window setting to reduce scatter. The Monte Carlo software SIMIND can be used to determine the DQE of a gamma camera system from a simulated point source alone. The optimal DQE results in the present study were obtained for parameter settings close to the clinically used settings.
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16.
  • Fredenberg, Erik, PhD, 1979-, et al. (författare)
  • Energy filtering with x-ray lenses: Optimization for photon-counting mammography
  • 2010
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 139, s. 339-342
  • Tidskriftsartikel (refereegranskat)abstract
    • Chromatic properties of the multi-prism and prism-array x-ray lenses (MPL and PAL) can potentially be utilized for efficient energy filtering and dose reduction in mammography. The line-shaped foci of the lenses are optimal for coupling to photon-counting silicon strip detectors in a scanning system. A theoretical model was developed and used to investigate the benefit of two lenses compared to an absorption-filtered reference system. The dose reduction of the MPL filter was 15% compared to the reference system at matching scan time, and the spatial resolution was higher. The dose of the PAL-filtered system was found to be 20% lower than for the reference system at equal scan time and resolution, and only 20% higher than for a monochromatic beam. An investigation of some practical issues remains, including the feasibility of brilliant-enough x-ray sources and manufacturing of a polymer PAL.
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17.
  • Förnvik, Daniel, et al. (författare)
  • THE EFFECT OF REDUCED BREAST COMPRESSION IN BREAST TOMOSYNTHESIS: HUMAN OBSERVER STUDY USING CLINICAL CASES.
  • 2010
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; Apr 7, s. 118-123
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim of this study was to investigate whether the compression force used with conventional mammography can be reduced with breast tomosynthesis (BT), without adversely affecting the visualisation of normal and pathological structures. Forty-five women were examined with BT using full (same as for 2D mammography) and half compression force. Both examinations were performed with the same acquisition parameters. A total of 103 paired structure images were evaluated according to specified image quality criteria. Three experienced radiologists participated in the study. They had to make a forced choice, i.e. choose the image they felt best fulfilled the image quality criteria. The results showed no evident difference in the image quality, indicating that BT may be performed with substantially less compression force compared with 2D mammography. A majority of the examined women felt that half compression was more comfortable than full compression.
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18.
  • Gudowska, Irena, et al. (författare)
  • Radiation burden from secondary doses to patients undergoing radiation therapy with photons and light ions and radiation doses from imaging modalities
  • 2014
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 161:1-4, s. 357-362
  • Tidskriftsartikel (refereegranskat)abstract
    • Ionising radiation is increasingly used for the treatment of cancer, being the source of a considerable fraction of the medical irradiation to patients. With the increasing success rate of cancer treatments and longer life expectancy of the treated patients, the issue of secondary cancer incidence is of growing concern, especially for paediatric patients who may live long after the treatment and be more susceptible to carcinogenesis. Also, additional imaging procedures like CT, kV and MV imaging and PET, alone or in conjunction with radiation therapy, may add to the radiation burden associated with the risk of occurrence of secondary cancers. This work has been based on literature studies and is focussed on the assessment of secondary doses to healthy tissues that are delivered by the use of modern radiation therapy and diagnostic imaging modalities in the clinical environment.
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19.
  • Hansson, Jonny, et al. (författare)
  • A practical approach to prioritise among optimisation tasks in X-ray imaging: introducing the 4-bit concept
  • 2010
  • Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 139:1-3, s. 393-399
  • Tidskriftsartikel (refereegranskat)abstract
    • According to European and national legislation, as well as international recommendations, X-ray examinations shall be optimised. However, with limited resources and hundreds of different types of X-ray examinations, it may be difficult to prioritise among the optimisation tasks at a radiology department. This work is focused on describing a method that can be used to determine the order of which the examinations should be optimised. In the Medical Exposure Directive from 1997, the European Commission prescribes the content of an optimisation process in relation to medical exposure. A reasonable interpretation of the directive is that the assurance of medical purpose for a justified examination is superior to the need of decreased radiation dose. This was used as a basis for developing a method for prioritisation among optimisation tasks. For each examination type, the following four yes/no questions are raised: (i) Is the present image quality unacceptable? (ii) Is the examination of particular importance? (iii) Is the radiation dose suspiciously high? (iv) Are there special dose level concerns, e.g. diagnostic reference levels? Arguing that a positive response to any of the four questions results in the examination being higher prioritised than otherwise and that the questions are labelled in order of decreasing relevance, it can be shown that the resulting flow chart, determining the order of which the examinations should be optimised, can be described by a 4-bit binary scale. In this way, each examination type is given a number from 0 to 15, a higher number corresponding to the examination being prioritised higher in the optimisation work. The method was applied to a general radiology department and resulted in a well-discriminated distribution of examinations prioritised for optimisation tasks. In conclusion, taking into account both medical outcome and potential risk, the proposed method can be used to determine the order in which examinations at a radiology department should be optimised.
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20.
  • Hansson, Jonny, et al. (författare)
  • Comparison of three methods for determining CT dose profile: presenting the tritium method
  • 2010
  • Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 139:1-3, s. 434-438
  • Tidskriftsartikel (refereegranskat)abstract
    • The purpose of the present work was to describe a method of using an imaging plate from a computed radiography system to determine the computed tomography (CT) dose profile (the tritium method) and to compare this method with point-dose measurements using a solid-state detector (CT Dose Profiler; RTI Electronics, Mölndal, Sweden) and the indirect method of comparing the air kerma-length product (P(KL)) at different beam collimations. The three methods were used to determine the full width at half maximum (FWHM) of the dose profile of a multi-slice CT at different nominal beam collimations. For all beam collimations, the obtained deviation between the tritium method and the CT Dose Profiler was smaller than 0.1 mm. The maximum relative error was 2 %. For the P(KL) method, the deviation from the CT Dose Profiler was between 0.2 and 0.4 mm, resulting in a relative error larger than 10 % for the smallest beam collimation even after normalisation to a known FWHM. In conclusion, the proposed method of using an imaging plate to determine the FWHM of the CT dose profile has a high accuracy and shows good agreement with the more advanced method of point-dose measurements using a solid-state detector.
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21.
  • Hansson, Mats, et al. (författare)
  • VISUALISATION AND QUANTIFICATION OF LUNG CONTENT OF RADIONUCLIDES ASSOCIATED WITH NUCLEAR AND RADIOLOGICAL EMERGENCIES.
  • 2011
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 145, s. 341-350
  • Tidskriftsartikel (refereegranskat)abstract
    • In a situation when radionuclides accidentally or deliberately are dispersed in the environment, there is a need for rapid investigation of the internal contamination in exposed individuals. In this work, the possibilities of visualising and quantifying uptakes of different radionuclides in the lung region of an adult individual using gamma camera systems have been examined, mainly on a two-headed stationary clinical gamma camera. An anthropomorphic phantom was used to mimic acute lung uptakes in three different body sizes. The gamma camera was calibrated with the lung inserts filled with a homogeneous solution of (99)Tc(m), (46)Sc and (32)P, or with point sources of (241)Am, (57)Co, (85)Sr, (137)Cs and (90)Sr/(90)Y. It was found that for the stationary gamma camera the minimum detectable activity in the lungs using a 5-min acquisition time ranged from 0.53 kBq for (46)Sc to 50 kBq for (32)P. Furthermore, the point sources of (137)Cs, (60)Co and (90)Sr/(90)Y (0.16, 0.80 and 2.2 MBq, respectively) located in the lung insert of the phantom, could be clearly visualised, exhibiting distinct intensity maxima. It is thus concluded that gamma camera systems can be useful for rapid assessment of acute intakes of radionuclides associated with emergency preparedness, both in terms of localisation and quantification.
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22.
  • Helmrot, Ebba, et al. (författare)
  • METHODS FOR MONITORING PATIENT DOSEIN DENTAL RADIOLOGY
  • 2010
  • Ingår i: Radiation Protection Dosimetry. - Oxford : Oxford University Press. - 0144-8420 .- 1742-3406. ; 139:1-3, s. 303-305
  • Tidskriftsartikel (refereegranskat)abstract
    • Different types of X-ray equipment are used in dental radiology, such as intra-oral, panoramic, cephalometric, cone-beam computed tomography (CBCT) and multi-slice computed tomography (MSCT) units. Digital receptors have replaced film and screen-film systems and other technical developments have been made. The radiation doses arising from different types of examination are sparsely documented and often expressed in different radiation quantities. In order to allow the comparison of radiation doses using conventional techniques, i.e. intra-oral, panoramic and cephalometric units, with those obtained using, CBCT or MSCT techniques, the same units of dose must be used. Dose determination should be straightforward and reproducible, and data should be stored for each image and clinical examination. It is suggested here that air kerma-area product (PKA) values be used to monitor the radiation doses used in all types of dental examinations including CBCT and MSCT. However, for the CBCT and MSCT techniques, the estimation of dose must be more thoroughly investigated. The values recorded can be used to determine diagnostic standard doses and to set diagnostic reference levels for each type of clinical examination and equipment used. It should also be possible to use these values for the estimation and documentation of organ or effective doses. 
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23.
  • Hemdal, Bengt (författare)
  • FORWARD-SCATTERED RADIATION FROM THE COMPRESSION PADDLE SHOULD BE CONSIDERED IN GLANDULAR DOSE ESTIMATIONS.
  • 2011
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 147, s. 196-201
  • Tidskriftsartikel (refereegranskat)abstract
    • From major protocols on dosimetry in mammography, there is no doubt that the incident air kerma should be evaluated without backscattered radiation to the dosemeter. However, forward-scattered radiation from the compression paddle is neglected. The aim of this work was to analyse the contribution of forward-scattered radiation for typical air kerma measurements. Measurements of forward-scatter were performed with a plane-parallel ionisation chamber on four mammography units. The forward-scatter contribution to the air kerma was 2-10 % and increased with the compression paddle thickness, but also with the half-value layer value. For incident air kerma in mammography, it can be as important to consider forward-scattered as backscattered radiation. If an ionisation chamber is used, the compression paddle should be in contact with the chamber; otherwise the air kerma and absorbed dose will be underestimated. If a dosemeter based on semiconductors with much less sensitivity to scattered radiation is used, it is suggested that a forward-scatter factor (FSF) is applied. Based on the results of this work, FSF=1.06 will lead to a maximum error of ∼4 %.
  •  
24.
  • Hoeschen, C., et al. (författare)
  • Minimising activity and dose with enhanced image quality by radiopharmaceutical administrations
  • 2010
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 139:1-3, s. 250-253
  • Tidskriftsartikel (refereegranskat)abstract
    • Owing to the introduction of new diagnostic procedures, such as computed tomography (CT), positron emission tomography (PET) and single photon emission computed tomography (SPECT), the individual dose caused by medical exposures has grown rapidly in the last years. This is especially a subject to radiation protection for nuclear medical diagnosis, since in this case radiopharmaceuticals are administered to the patient, meaning not only a radiation exposure to the diseased tissue but also to the healthy tissues of large parts of the body. 'Minimizing Activity and Dose with Enhanced Image quality by Radiopharmaceutical Administrations' (MADEIRA) is a project cofunded by the European Commission within the Seventh Euratom Framework Programme that aims to improve three-dimensional (3D) nuclear medical imaging technologies significantly. MADEIRA is aiming to improve the efficacy and safety of 3D PET and SPECT functional imaging by optimising the spatial resolution and the signal-to-noise ratio, improving the knowledge of the temporal variation of the radiopharmaceuticals' uptake in and clearance from tumourous and healthy tissues, and evaluation of the corresponding patient dose. Using an optimised imaging procedure that improves the information gained per unit administered dose, MADEIRA aims especially to reduce the dose to healthy tissues of the patient. In this paper, an overall summary of the current achievements will be presented.
  •  
25.
  • Horton, P., et al. (författare)
  • Introduction to suspension levels: radiotherapy
  • 2013
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 153:2, s. 174-178
  • Tidskriftsartikel (refereegranskat)abstract
    • In 2007, the European Commission (EC) commissioned a group of experts to undertake the revision of Report Radiation Protection (RP 91) oCriteria for acceptability of radiological (including radiotherapy) and nuclear medicine installations' written in 1997(( 1)). The revised draft report was submitted to the EC in 2010, who issued it for public consultation. The EC has commissioned the same group of experts to consider the comments of the public consultation for further improvement of the revised report. The EC intends to publish the final report under its Radiation Report Series as RP 162. This paper describes the background to the selection of the key performance parameters for radiotherapy equipment and sets out the sources of their criteria of acceptability including suspension levels for a wide range of radiotherapy equipment.
  •  
26.
  • Håkansson, Markus, et al. (författare)
  • ViewDEX: an efficient and easy-to-use software for observer performance studies
  • 2010
  • Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 139:1-3, s. 42-51
  • Tidskriftsartikel (refereegranskat)abstract
    • The development of investigation techniques, image processing, workstation monitors, analysing tools etc. within the field of radiology is vast, and the need for efficient tools in the evaluation and optimisation process of image and investigation quality is important. ViewDEX (Viewer for Digital Evaluation of X-ray images) is an image viewer and task manager suitable for research and optimisation tasks in medical imaging. ViewDEX is DICOM compatible and the features of the interface (tasks, image handling and functionality) are general and flexible. The configuration of a study and output (for example, answers given) can be edited in any text editor. ViewDEX is developed in Java and can run from any disc area connected to a computer. It is free to use for non-commercial purposes and can be downloaded from http://www.vgregion.se/sas/viewdex. In the present work, an evaluation of the efficiency of ViewDEX for receiver operating characteristic (ROC) studies, free-response ROC (FROC) studies and visual grading (VG) studies was conducted. For VG studies, the total scoring rate was dependent on the number of criteria per case. A scoring rate of approximately 150 cases h(-1) can be expected for a typical VG study using single images and five anatomical criteria. For ROC and FROC studies using clinical images, the scoring rate was approximately 100 cases h(-1) using single images and approximately 25 cases h(-1) using image stacks ( approximately 50 images case(-1)). In conclusion, ViewDEX is an efficient and easy-to-use software for observer performance studies.
  •  
27.
  • Häggström, Ida, 1982-, et al. (författare)
  • Semi-automatic tumour segmentation by selective navigation in a three-parameter volume, obtained by voxel-wise kinetic modelling of C-11-acetate
  • 2010
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 139:1-3, s. 214-218
  • Tidskriftsartikel (refereegranskat)abstract
    • Positron emission tomography (PET) is increasingly used for delineation of tumour tissue in, for example, radiotherapy treatment planning. The most common method used is to outline volumes with a certain per cent uptake over background in a static image. However, PET data can also be collected dynamically and analysed by kinetic models, which potentially represent the underlying biology better. In the present study, a three-parameter kinetic model was used for voxel-wise evaluation of C-11-acetate data of head/neck tumours. These parameters which represent the tumour blood volume, the uptake rate and the clearance rate of the tissue were derived for each voxel using a linear regression method and used for segmentation of active tumour tissue. This feasibility study shows that it is possible to segment images based on derived model parameters. There is, however, room for improvements concerning the PET data acquisition, noise reduction and the kinetic modelling. In conclusion, this early study indicates a strong potential of the method even though no 'true' tumour volume was available for validation.
  •  
28.
  • Israelsson, Axel, et al. (författare)
  • Dose response of xylitol and sorbitol for EPR retrospective dosimetry with applications to chewing gum
  • 2013
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 154:2, s. 133-141
  • Tidskriftsartikel (refereegranskat)abstract
    • 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).
  •  
29.
  • Johnsson, Åse (Allansdotter), 1966, et al. (författare)
  • A phantom study of nodule size evaluation with chest tomosynthesis and computed tomography.
  • 2010
  • Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 139:1-3, s. 140-143
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim of the present study was to investigate nodule size measurements with chest tomosynthesis (TS) and computed tomography (CT). A 26-mm thick phantom, composed of a Polylite block with embedded spheres of different materials and sizes (4-20 mm), was scanned by both CT and TS. Six observers without prior knowledge of the true diameters of the spheres independently measured the diameter of the spheres on the CT and TS images. Four observers were allowed to change the window settings and two of the observers used predetermined fixed viewing conditions. The mean relative errors for all observers and all measured spheres compared with the known diameter of the spheres were 1.4 % (standard deviation, SD: 5.4 %) on CT images and -1.1 % (SD: 5.0 %) on TS images. With regard to the four observers where the window settings were at the discretion of the observer, the mean relative errors were 1.4 % (SD: 6.4 %) on CT images and -1.7 % (SD: 5.7 %) on TS images. Regarding the two observers using identical viewing conditions the mean relative error was 1.5 % (SD: 2.8 %) on CT images and 0.2 % (SD: 2.6 %) on TS images. In conclusion, the study suggests that nodule size measurements on chest TS might be an alternative to measurements on CT.
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30.
  • Johnsson, Åse (Allansdotter), 1966, et al. (författare)
  • Overview of two years of clinical experience of chest tomosynthesis at Sahlgrenska University Hospital.
  • 2010
  • Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 139:1-3, s. 124-129
  • Tidskriftsartikel (refereegranskat)abstract
    • Since December 2006, approximately 3800 clinical chest tomosynthesis examinations have been performed at our department at Sahlgrenska University Hospital. A subset of the examinations has been included in studies of the detectability of pulmonary nodules, using computed tomography (CT) as the gold standard. Visibility studies, in which chest tomosynthesis and CT have been compared side-by side, have been used to determine the depiction potential of chest tomosynthesis. Comparisons with conventional chest radiography have been made. In the clinical setting, chest tomosynthesis has mostly been used as an additional examination. The most frequent indication for chest tomosynthesis has been suspicion of a nodule or tumour. In visibility studies, tomosynthesis has depicted over 90 % of the nodules seen on the CT scan. The corresponding figure for chest radiography has been <30 %. In the detection studies, the lesion-level sensitivity has been approximately 60 % for tomosynthesis and 20 % for chest radiography. In one of the detection studies, an analysis of all false-positive nodules was performed. This analysis showed that all findings had morphological correlates on the CT examinations. The majority of the false-positive nodules were localised in the immediate subpleural region. In conclusion, chest tomosynthesis is an improved chest radiography method, which can be used to optimise the use of CT resources, thereby reducing the radiation dose to the patient population. However, there are some limitations with chest tomosynthesis. For example, patients undergoing tomosynthesis have to be able to stand still and hold their breath firmly for 10 s. Also, chest tomosynthesis has a limited depth resolution, which may explain why pathology in the subpleural region is more difficult to interpret and artefacts from medical devices may occur.
  •  
31.
  • Kolbun, Natallia, et al. (författare)
  • High-resolution mapping of 1D and 2D dose distributions using X-band electron paramagnetic resonance imaging
  • 2014
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press. - 0144-8420 .- 1742-3406. ; 159:1-4, s. 182-187
  • Tidskriftsartikel (refereegranskat)abstract
    • Electron paramagnetic resonance imaging (EPRI) was performed to visualise 2D dose distributions of homogenously irradiated potassium dithionate tablets and to demonstrate determination of 1D dose profiles along the height of the tablets. Mathematical correction was applied for each relative dose profile in order to take into account the inhomogeneous response of the resonator using X-band EPRI. The dose profiles are presented with the spatial resolution of 0.6 mm from the acquired 2D images; this value is limited by pixel size, and 1D dose profiles from 1D imaging with spatial resolution of 0.3 mm limited by the intrinsic line-width of potassium dithionate. In this paper, dose profiles from 2D reconstructed electron paramagnetic resonance (EPR) images using the Xepr software package by Bruker are focussed. The conclusion is that using potassium dithionate, the resolution 0.3 mm is sufficient for mapping steep dose gradients if the dosemeters are covering only +/- 2 mm around the centre of the resonator.
  •  
32.
  • Kulka, U., et al. (författare)
  • Realising the European Network of Biodosimetry (RENEB)
  • 2012
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 151:4, s. 621-625
  • Tidskriftsartikel (refereegranskat)abstract
    • In Europe, a network for biological dosimetry has been created to strengthen the emergency preparedness and response capabilities in case of a large-scale nuclear accident or radiological emergency. Through the RENEB (Realising the European Network of Biodosimetry) project, 23 experienced laboratories from 16 European countries will establish a sustainable network for rapid, comprehensive and standardised biodosimetry provision that would be urgently required in an emergency situation on European ground. The foundation of the network is formed by five main pillars: (1) the ad hoc operational basis, (2) a basis of future developments, (3) an effective quality-management system, (4) arrangements to guarantee long-term sustainability and (5) awareness of the existence of RENEB. RENEB will thus provide a mechanism for quick, efficient and reliable support within the European radiation emergency management. The scientific basis of RENEB will concurrently contribute to increased safety in the field of radiation protection.
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33.
  • Lamm, Inger-Lena, et al. (författare)
  • PRACTICAL APPLICATION OF SUSPENSION CRITERIA SCENARIOS: RADIOTHERAPY.
  • 2013
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 153:2, s. 179-184
  • Tidskriftsartikel (refereegranskat)abstract
    • In 2007, the European Commission (EC) commissioned a group of experts to undertake the revision of Report RP91 'Criteria for Acceptability of Radiological (including Radiotherapy) and Nuclear Medicine Installations' written in 1997. The revised draft report was submitted to the EC in 2010, which issued it for public consultation. The EC commissioned the same group of experts to consider the comments of the public consultation for further improvement of the revised report. The EC intends to publish the final report under its Radiation Report Series as RP162. This paper presents a selection of practical applications of suspension criteria scenarios in radiotherapy, mostly in brachytherapy, with special emphasis on the critical roles and responsibilities of qualified radiotherapy staff (radiation oncologists, medical physicists and radiotherapy technicians).
  •  
34.
  • Larsson, Lars E, et al. (författare)
  • Harmonisation of the appearance of digital radiographs from different vendors by means of common external image processing
  • 2010
  • Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 139:1-3, s. 92-97
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim of the present study was to evaluate the use of common external image processing to compensate for differences in appearance between digital X-ray images from different vendors. Twenty posteroanterior chest radiographs were collected from each of three different modalities from different vendors (GE, Siemens and Canon) with vendor-specific image processing applied. The images were also extracted with neutral process parameters and processed with external image-processing software. Six experienced radiologists rated the quality and the similarity of the images with the original Siemens images. The externally processed GE images were rated of higher quality than the original GE images and more similar to the original Siemens images (p < 0.001). The opposite was obtained for the Canon images. The externally processed Siemens images were rated of similar quality as the original images. The present study indicates the possibility of using common external image processing to harmonise the appearance of images from different vendors, although the exposure parameters may need to be adjusted for individual vendors.
  •  
35.
  • Leander, Peter, et al. (författare)
  • Post-processing image filtration enabling dose reduction in standard abdominal CT
  • 2010
  • Ingår i: RADIATION PROTECTION DOSIMETRY. - : Oxford University Press. - 0144-8420 .- 1742-3406. ; 139:1-3, s. 180-185
  • Tidskriftsartikel (refereegranskat)abstract
    • The collective effective radiation dose to the population is increasing due to a higher use of computerised tomography. SharpView AB, Linkoping, Sweden, has developed an adaptive non-linear post-processing image filtration that may enable the use of lower radiation doses. The present study assessed if a lower dose with image filtration had the same image quality as a higher dose without the filter applied. All imaging was performed on a Siemens Somatom Sensation 16 CT. The parameters used were 120 kV and 200 mAs (40 patients) and 130 mAs without and with image filtering (40 patients), respectively. All studies were quantitatively evaluated for noise and image quality was assessed by visual grading characteristics (VGC) analysis. After image filtration, the noise in the processed images was lowered and the image quality was improved as shown by the VGC analysis. However, images using the higher dose were still ranked as the best in five out of eight criteria as shown by the VGC analysis. Image filtration enhances CT images significantly and further studies will show if 130 mAs with image filtration may be sufficient for clinically general abdominal CT.
  •  
36.
  • Ledenius, Kerstin, 1979, et al. (författare)
  • Evaluation Of Image-Enhanced Paediatric Computed Tomography Brain Examinations
  • 2010
  • Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 139:1-3, s. 287-292
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim of this study was to evaluate the possibility of reducing the radiation dose to paediatric patients undergoing computed tomography (CT) brain examination by using image-enhancing software. Artificial noise was added to the raw data collected from 20 patients aged between 1 and 10 y to simulate tube current reductions of 20, 40 and 60 mA. All images were created in duplicate; one set of images remained unprocessed whereas the other was processed with image-enhancing software. Three paediatric radiologists assessed the image quality based on their ability to visualise the high- and low-contrast structures and their overall impression of the diagnostic value of the image. For patients aged 6-10 y, it was found that dose reductions from 27 mGy (CTDI(vol)) to 23 mGy (15 %) in the upper brain and from 32 to 28 mGy (13 %) in the lower brain were possible for standard diagnostic CT examinations when using the image-enhancing filter. For patients 1-5 y, the results for standard diagnostics in the upper brain were inconclusive, for the lower brain no dose reductions were found possible.
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37.
  • Leide Svegborn, Sigrid (författare)
  • External radiation exposure of personnel in nuclear medicine from F-18, Tc-99m and I-131 with special reference to fingers, eyes and thyroid
  • 2012
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 149:2, s. 196-206
  • Tidskriftsartikel (refereegranskat)abstract
    • The radiation exposure of fingers, thyroid and eyes of workers handling radiopharmaceuticals during various nuclear medicine procedures was measured using thermoluminescent dosemeters. Dosemeters were placed on the finger tips of 19 workers on several different occasions for various procedures. Additionally, the routinely determined whole-body doses to various groups of workers were analysed. The finger dose measurements demonstrated clear differences between the various tasks, from 0.0012 µGy MBq(-1) (unpacking and installing (99)Mo/(99m)Tc-generator) to 3.0 µGy MBq(-1) (syringe withdrawal, injection and waste handling of (18)F-FDG). As long as the worker was handling (99m)Tc, the dose to the fingers was well below the ICRP dose limits, even when the activity was high. Special concern should, however, be devoted to the handling of (18)F, since the dose to the fingers could easily reach the dose limits. The estimated dose to eyes and thyroid was well below the dose limits. Since the introduction of the positron emission tomography/computed tomography facility, the annual whole-body dose has increased for those directly involved in the handling of (18)F. The annual whole-body dose of 0.2-2.5 mGy was, however, well below the dose limits.
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38.
  • Leide Svegborn, Sigrid (författare)
  • Radiation exposure of patients and personnel from a PET/CT procedure with F-18-FDG
  • 2010
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 139:1-3, s. 208-213
  • Tidskriftsartikel (refereegranskat)abstract
    • The positron emission tomography (PET)/computed tomography (CT) camera is a combination of a PET camera and a CT. The image from the PET camera is based on the detection of radiation that is emitted from a radioactive tracer, which has been given to the patient as an intravenous injection. The radiation that is emitted from the radioactive tracer is more energetic than any other radiation used in medical diagnostic procedures and this requires special radiation protection routines. The CT image is based on the detection of radiation produced from an X-ray tube and transmitted through the patient. The radiation exposure of the personnel during the CT procedure is generally very low. Regarding radiation exposure of the patient, it is important to notice whether a CT scan has been performed prior to the PET/CT in order to avoid any unnecessary irradiation. The total effective dose to the patient from a PET/CT procedure is approximately 10 mSv. The major part comes from internal irradiation due to radiopharmaceuticals within the patients (e.g. (18)F-FDG: approximately 6-7 mSv), and a minor part is due to the CT scan (low-dose CT scan: approximately 2-4 mSv). If a full diagnostic CT investigation is performed, the effective dose may be considerably higher. If the patient is pregnant, a PET/CT procedure should be avoided or postponed, unless it is vital for the patient. An interruption in breastfeeding is not necessary after a PET/CT procedure of the nursing mother. Close contact between the patient and a small child should however be avoided for a couple of hours after the administration of the radiopharmaceutical. The radiation dose to the personnel arises mainly due to handling of the radiopharmaceuticals (syringe withdrawal, injection, waste handling, etc.) and from close contact to the patient. This radiation dose can be limited by using the inverse-square law, i.e. by using the fact that the absorbed dose decreases substantially with increasing distance between the radiation source and the personnel.
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39.
  • Liamsuwan, Thiansin, et al. (författare)
  • A model of carbon ion interactions in water using the classical trajectory Monte Carlo method
  • 2011
  • Ingår i: International Journal of Radiation Biology. - : Oxford University Press (OUP). - 0955-3002 .- 1362-3095. ; 143:2-4, s. 152-155
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper, model calculations for interactions of C6+ of energies from 1 keV u−1 to 1 MeV u−1 in water are presented. The calculations were carried out using the classical trajectory Monte Carlo method, taking into account the dynamic screening of the target core. The total cross sections (TCS) for electron capture and ionisation, and the singly and doubly differential cross sections (SDCS and DDCS) for ionisation were calculated for the five potential energy levels of the water molecule. The peaks in the DDCS for the electron capture to continuum and for the binary-encounter collision were obtained for 500-keV u−1 carbon ions. The calculated SDCS agree reasonably well with the z2 scaled proton data for 500 keV u−1 and 1 MeV u−1 projectiles, but a large deviation of up to 8-folds was observed for 100-keV u−1 projectiles. The TCS for ionisation are in agreement with the values calculated from the first born approximation (FBA) at the highest energy region investigated, but become smaller than the values from the FBA at the lower-energy region.                
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40.
  •  
41.
  • Lund, Eva, et al. (författare)
  • EPR imaging of dose distributions aiming at applications in radiation therapy
  • 2014
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press. - 0144-8420 .- 1742-3406. ; 159:1-4, s. 130-136
  • Tidskriftsartikel (refereegranskat)abstract
    • A one-dimensional electron paramagnetic resonance (EPR) imaging method for visualisation of dose distributions in photon fields has been developed. Pressed pellets of potassium dithionate were homogeneously irradiated in a Co-60 radiation field to 600 Gy. The EPR analysis was performed with an X-Band (9.6 GHz) Bruker E540 EPR and EPR imaging spectrometer equipped with an E540 GC2X two-axis X-band gradient coil set with gradients along the y axis (along the sample tube) and z axis (along B-0) and an ER 4108TMHS resonator. Image reconstruction, including deconvolution, baseline corrections and corrections for the resonator sensitivity, was performed using an in-house-developed Matlab code for the purpose to have a transparent and complete algorithm for image reconstruction. With this method, it is possible to visualise a dose distribution with an accuracy of similar to 5 % within +/- 5 mm from the centre of the resonator.
  •  
42.
  •  
43.
  • Mattsson, Sören, et al. (författare)
  • ICRP perspective on criteria of acceptability for medical radiological equipment
  • 2013
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 153:2, s. 158-160
  • Tidskriftsartikel (refereegranskat)abstract
    • The International Commission on Radiological Protection (ICRP) does not have a specific publication or recent detailed advice on acceptability criteria and suspension levels for medical radiological equipment. However, a number of the Commission's publications clearly stress the need to carry out acceptance testing of radiological equipment. Such general recommendations are frequent in earlier and recent reports related to external radiation therapy. Over 30 y ago, the ICRP even included some examples of parameter accuracies concerning acceptance levels in connection with radiotherapy units. Later more general advices related to acceptability tests as important parts of various quality assurance programs were formulated for radiation therapy as well as for radiodiagnostics without going into details to give values for specific parameters. In the radiodiagnostic field, there are such general recommendations in reports related to equipment for X-ray interventional procedures, digital radiology and computed tomography. The ICRP highly supports the elaboration of detailed and clear acceptability and suspension criteria for equipment used in medical radiology carried out by organisations like International Atomic Energy Agency, International Electrotechnical Commission, European Commission, National Electrical Manufacturers Association (NEMA, USA) and others and consider such criteria as important parts of the quality programmes to guarantee good radiation safety conditions for patients in radiation therapy as well as in radiodiagnostics.
  •  
44.
  • Mattsson, Sören, et al. (författare)
  • RADIATION DOSE MANAGEMENT IN CT, SPECT/CT AND PET/CT TECHNIQUES.
  • 2011
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 147, s. 13-21
  • Tidskriftsartikel (refereegranskat)abstract
    • New imaging technologies utilising X rays and radiopharmaceuticals are continuously under development. The benefit of computed tomography (CT) has been so dramatic that there is a tendency to overuse it and not to place enough efforts into optimisation of the technique. It is also now more and more common to combine two imaging techniques into a single investigation, such as PET/CT and SPECT/CT-the so-called 'hybrid imaging'. The increasing radiation exposure from CT has been of concern for some years and is now receiving increased attention from health professionals, authorities, manufacturers and patient groups. The relatively high radiation doses from PET and SPECT investigations have only recently been discussed. The aim of this article is to provide information on developing technologies and clinical techniques for 3D imaging using ionising radiation and their associated radiation dose to patients and staff. Tools for improved dose management are also discussed.
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45.
  • Mattsson, Sören, et al. (författare)
  • Special issue: Medical imaging--optimisation in X-ray and molecular imaging.
  • 2010
  • Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 139:1-3, s. 1-2
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • This issue of Radiation Protection Dosimetry is based on contributions to the Third Malmö Conference on Medical Imaging, which was held from 25 to 27 June 2009 at the Malmö University Hospital, Sweden. The conference was jointly organised by members of current and former research projects supported by the European Commission EURATOM-Radiation Protection Research Programme.
  •  
46.
  •  
47.
  • Nilsson, Jenny, et al. (författare)
  • A comparison between Monte Carlo-calculated and -measured total efficiencies and energy resolution for large plastic scintillators used in whole-body counting.
  • 2011
  • Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 144:1-4, s. 555-9
  • Tidskriftsartikel (refereegranskat)abstract
    • The measured total efficiency for several source positions has been determined for a large, plastic scintillation detector (NE 102A, 91.5 × 76.0 × 24.5 cm(3)) used for whole-body counting gamma spectrometry. The results have been compared with Monte Carlo-calculated total efficiencies; the code used was MCNPX 2.60. For (137)Cs, there was a good agreement between the measured and calculated total efficiencies. MXNPX was also used to calculate the electron light yield for (137)Cs; for the detector material NE 102A, Birks' constant kB was found to be 9.6 mg cm(-2) MeV(-1). The effect of light losses on spectrum resolution has been investigated for (65)Zn.
  •  
48.
  • Pachnerova Brabcová, Katerina, 1978, et al. (författare)
  • Dose Distribution Outside the Target Volume for 170-Mev Proton Beam
  • 2014
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 161:1-4, s. 410-416
  • Tidskriftsartikel (refereegranskat)abstract
    • Dose delivered outside the proton field during radiotherapy can potentially lead to secondary cancer development. Measurements with a 170-MeV proton beam were performed with passive detectors (track etched detectors and thermoluminescence dose-meters) in three different depths along the Bragg curve. The measurement showed an uneven decrease of the dose outside of the beam field with local enhancements. The major contribution to the delivered dose is due to high-energy protons with linear energy transfer (LET) up to 10 keV mu m(-1). However, both measurement and preliminary Monte Carlo calculation also confirmed the presence of particles with higher LET.
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49.
  • Persson, Anders, 1953- (författare)
  • Will medical visualisation tools meet medical user requirements in the future?
  • 2010
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press. - 0144-8420 .- 1742-3406. ; 139:1-3, s. 12-19
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper describes state-of-the-art medical visualisation and discusses the need for a research agenda that focuses on the development of the next generation of medical acquisition and visualisation tools, emphasising the fact that these tools must be based on medical user requirement and workflow studies as well as on new technical developments.
  •  
50.
  • Pola, A., et al. (författare)
  • Compact Thermal Neutron Sensors for Moderator-Based Neutron Spectrometers
  • 2014
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 161:1-4, s. 229-232
  • Tidskriftsartikel (refereegranskat)abstract
    • In the framework of the NESCOFI@BTF project of the Italian Institute of Nuclear Physics, different types of active thermal neutron sensors were studied by coupling semiconductor devices with a suitable radiator. The objective was to develop a detector of small dimensions with a proper sensitivity to use at different positions in a novel moderating assembly for neutron spectrometry. This work discusses the experimental activity carried out in the framework of the ERINDA program (PAC 3/9 2012) to characterise the performance of a thermal neutron pulse detector based on Li-6.
  •  
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