| 1. |
- Abul-Kasim, Kasim
(författare)
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LOW-DOSE SPINE CT: OPTIMISATION AND CLINICAL IMPLEMENTATION.
- 2010
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 139, s. 169-172
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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. |
- Adolfsson, Emelie, et al.
(författare)
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END-TO-END AUDIT: COMPARISON OF TLD AND LITHIUM FORMATE EPR DOSIMETRY
- 2019
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Ingår i: Radiation Protection Dosimetry. - : OXFORD UNIV PRESS. - 0144-8420 .- 1742-3406. ; 186:1, s. 119-122
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to test two different solid state dosimetry systems for the purpose of end-to-end audits of radiotherapy volumetric modulated arc therapy (VMAT) technique; a lithium formate electron paramagnetic resonance system and a lithium fluoride thermoluminescent dosimetry system. As a complement to the solid state systems, ion chamber measurements were performed. A polystyrene phantom with a planning target volume (PTV) and an organ at risk (OAR) structure was scanned using CT. A VMAT dose plan was optimized to deliver 2 Gy to the target volume and to minimize the dose to the OAR. The different detectors were inserted into the phantom and the planned dose distribution was delivered. The measured doses were compared to the treatment planning system (TPS) calculated doses. Good agreement was found between the TPS calculated and the measured doses, well accepted for the dose determinations in remote dosimetry audits of VMAT treatment technique.
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| 3. |
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| 4. |
- Ainsbury, E A, et al.
(författare)
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REVIEW OF RETROSPECTIVE DOSIMETRY TECHNIQUES FOR EXTERNAL IONISING RADIATION EXPOSURES.
- 2011
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 147:4, s. 573-592
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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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| 5. |
- Ainsbury, Elizabeth A., et al.
(författare)
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UNCERTAINTY ON RADIATION DOSES ESTIMATED BY BIOLOGICAL AND RETROSPECTIVE PHYSICAL METHODS
- 2018
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Ingår i: Radiation Protection Dosimetry. - : OXFORD UNIV PRESS. - 0144-8420 .- 1742-3406. ; 178:4, s. 382-404
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Tidskriftsartikel (refereegranskat)abstract
- Biological and physical retrospective dosimetry are recognised as key techniques to provide individual estimates of dose following unplanned exposures to ionising radiation. Whilst there has been a relatively large amount of recent development in the biological and physical procedures, development of statistical analysis techniques has failed to keep pace. The aim of this paper is to review the current state of the art in uncertainty analysis techniques across the EURADOS Working Group 10-Retrospective dosimetry members, to give concrete examples of implementation of the techniques recommended in the international standards, and to further promote the use of Monte Carlo techniques to support characterisation of uncertainties. It is concluded that sufficient techniques are available and in use by most laboratories for acute, whole body exposures to highly penetrating radiation, but further work will be required to ensure that statistical analysis is always wholly sufficient for the more complex exposure scenarios.
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| 6. |
- Almén, Anja, 1964, et al.
(författare)
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A CONCEPTUAL FRAMEWORK FOR MANAGING RADIATION DOSE TO PATIENTS IN DIAGNOSTIC RADIOLOGY USING REFERENCE DOSE LEVELS
- 2016
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Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 169:1-4, s. 17-23
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Tidskriftsartikel (refereegranskat)abstract
- The overall aim of the present work was to develop a conceptual framework for managing radiation dose in diagnostic radiology with the intention to support optimisation. An optimisation process was first derived. The framework for managing radiation dose, based on the derived optimisation process, was then outlined. The outset of the optimisation process is four stages: providing equipment, establishing methodology, performing examinations and ensuring quality. The optimisation process comprises a series of activities and actions at these stages. The current system of diagnostic reference levels is an activity in the last stage, ensuring quality. The system becomes a reactive activity only to a certain extent engaging the core activity in the radiology department, performing examinations. Three reference dose levels-possible, expected and established-were assigned to the three stages in the optimisation process, excluding ensuring quality. A reasonably achievable dose range is also derived, indicating an acceptable deviation from the established dose level. A reasonable radiation dose for a single patient is within this range. The suggested framework for managing radiation dose should be regarded as one part of the optimisation process. The optimisation process constitutes a variety of complementary activities, where managing radiation dose is only one part. This emphasises the need to take a holistic approach integrating the optimisation process in different clinical activities.
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| 7. |
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| 8. |
- Almén, Anja, 1964, et al.
(författare)
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OPTIMISATION OF OCCUPATIONAL RADIATION PROTECTION IN IMAGE-GUIDED INTERVENTIONS: EXPLORING VIDEO RECORDINGS AS A TOOL IN THE PROCESS
- 2016
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Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 169:1-4, s. 425-429
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Tidskriftsartikel (refereegranskat)abstract
- The overall purpose of this work was to explore how video recordings can contribute to the process of optimising occupational radiation protection in image-guided interventions. Video-recorded material from two image-guided interventions was produced and used to investigate to what extent it is conceivable to observe and assess dose-affecting actions in video recordings. Using the recorded material, it was to some extent possible to connect the choice of imaging techniques to the medical events during the procedure and, to a less extent, to connect these technical and medical issues to the occupational exposure. It was possible to identify a relationship between occupational exposure level to staff and positioning and use of shielding. However, detailed values of the dose rates were not possible to observe on the recordings, and the change in occupational exposure level from adjustments of exposure settings was not possible to identify. In conclusion, the use of video recordings is a promising tool to identify dose-affecting instances, allowing for a deeper knowledge of the interdependency between the management of the medical procedure, the applied imaging technology and the occupational exposure level. However, for a full information about the dose-affecting actions, the equipment used and the recording settings have to be thoroughly planned.
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| 9. |
- Almén, A, et al.
(författare)
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Personal Dosimetry Using Monte-Carlo Simulations For Occupational Dose Monitoring In Interventional Radiology : The Results Of A Proof Of Concept In A Clinical Setting
- 2021
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 195:44624, s. 391-398
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Tidskriftsartikel (refereegranskat)abstract
- Exposure levels to staff in interventional radiology (IR) may be significant and appropriate assessment of radiation doses is needed. Issues regarding measurements using physical dosemeters in the clinical environment still exist. The objective of this work was to explore the prerequisites for assessing staff radiation dose, based on simulations only. Personal dose equivalent, Hp(10), was assessed using simulations based on Monte Carlo methods. The position of the operator was defined using a 3D motion tracking system. X-ray system exposure parameters were extracted from the x-ray equipment. The methodology was investigated and the simulations compared to measurements during IR procedures. The results indicate that the differences between simulated and measured staff radiation doses, in terms of the personal dose equivalent quantity Hp(10), are in the order of 30-70 %. The results are promising but some issues remain to be solved, e.g. an automated tracking of movable parts such as the ceiling-mounted protection shield.
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| 10. |
- Ambrozova, I., et al.
(författare)
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Microdosimetry for a carbon ion beam using track-etched detectors
- 2015
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 166:1-4, s. 247-252
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Tidskriftsartikel (refereegranskat)abstract
- Track-etched detectors (TED) have been used as linear energy transfer (LET) spectrometers in heavy ion beams for many years. LET spectra and depth-dose distribution of a carbon ion beam were measured behind polymethylmethacrylate degraders at Heavy Ion Medical Accelerator in Chiba, Japan. The measurements were performed along monoenergetic beam with energy 290 MeV u-1 in different positions: (1) at beam extraction area, (2) at beginning, (3) maximum and (4) behind the Bragg peak region (0, 117, 147 and 151 mm of water-equivalent depth, respectively). The LET spectra inside and outside of the primary ion beam have been evaluated. TED record only heavy charged particles with LET above 8-10 keV μm-1, while electrons and ions with lower LET are not detected. The Geant4 simulation toolkit version 4.9.6.P01 has been used to estimate the contribution of non-detected particles to absorbed dose. Presented results demonstrate the applicability of TED for microdosimetry measurements in therapeutic carbon ion beams.
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| 11. |
- Andersen, C. E., et al.
(författare)
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An algorithm for real-time dosimetry in intensity-modulated radiation therapy using the radioluminescence signal from Al2O3 : C
- 2006
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 120:1-4, s. 41468-41468
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Tidskriftsartikel (refereegranskat)abstract
- Although the radioluminescence (RL) signal from optical fibre Al2O3:C dosemeters used in medical applications is essentially proportional to dose rate, the crystals used so far are imperfect in the sense that their RL sensitivity changes with accumulated dose. A computational algorithm has been developed that corrects for these sensitivity changes. We further report on a new system that effectively separates the RL signal generated in the crystal from fluorescence and Cerenkov emission generated in the optical fibre cable using a gating technique in connection with pulsed linear accelerator radiation beams. The dosimetry system has been used for dose measurements in a phantom during an intensity-modulated radiation therapy (IMRT) treatment with 6 MV photons. The RL measurement results are in excellent agreement (i.e. within 1%) with both the OSL results and the dose delivered according to the treatment planning system. RL signals from Al2O3:C can be used for real-time dose rate measurements with a time resolution of similar to 0.1 s and a spatial resolution only limited by the size of the detector (< 0.5 mm).
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| 12. |
- Andersson, Martin, et al.
(författare)
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An internal radiation dosimetry computer program, IDAC 2.0, for estimation of patient doses from radiopharmaceuticals
- 2014
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 162:3, s. 299-305
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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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| 13. |
- Andersson, Martin, et al.
(författare)
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Dosimetry and Cancer Risk Estimations for Different Radiation Protection Solutions at Decommissioning a Contaminated Nuclear Power Plant Site
- 2022
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 198:19, s. 1516-1521
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Tidskriftsartikel (refereegranskat)abstract
- Contaminated sediments originating from dredging activities in a nuclear power plant site were placed in a pond, which has to be taken into consideration during the future decommissioning process. The sediments have to be handled to free release the site. The radionuclides Co-60 and Cs-137 were identified and the activity concentrations (Bq/kg) were quantified in the range of 10-6000 and 5-50 Bq kg(-1), respectively. The absorbed dose rate to individuals of various ages and sex present at the site of the dry pond area was estimated. The radiological impact in terms of lifetime attributable risk (LAR) and effective dose were calculated. For a 30-year-old male exposed during one year without any action regarding the sediments in the dried out pond, the LAR was predicted to be 0.0027, which recalculated to effective dose corresponds to 7.6 mSv year(-1). The calculations show that countermeasures will be needed for the contaminated site.
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| 14. |
- Andersson, Martin, et al.
(författare)
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IDAC-ALPHA: AN ALPHA DOSIMETRY SOFTWARE FOR NORMAL ORGANS AND TISSUES
- 2021
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 195:3-4, s. 327-333
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Tidskriftsartikel (refereegranskat)abstract
- Radiopharmaceuticals have been used for the treatment of various forms of cancer since the 1940s. In recent years, the advantages of alpha emitting radionuclides have emerged as a favourable treatment option. However, most alpha emitting radionuclides have long decay chains with long-lived daughter radionuclides. This leads to uncertainties in the dosimetry for normal organs and tissues, when established dosimetry models are employed. The aim of this project is to assign each progeny its own biokinetic behaviour. The novel dosimetry model was applied to Ra-223-dichloride, frequently used for the treatment of patients with metastatic bone disease from castration-resistant prostate cancer. In this dosimetry model, individual biokinetics for each daughter radionuclide was included. This resulted in a decrease in absorbed dose to bone surfaces and red marrow and increased absorbed dose to liver and kidney, when compared with dosimetry models assuming that the daughter nuclides follow the biokinetics of the parent radionuclide.
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| 15. |
- Andersson, Martin, et al.
(författare)
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Improved age and gender specific radiation risk models applied on cohorts of Swedish patients
- 2021
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 195:3-4, s. 334-338
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Tidskriftsartikel (refereegranskat)abstract
- AIM:The aim of this study is to implement lifetime attributable risk (LAR) predictions for radiation induced cancers for Swedish cohorts of patients of various age and sex, undergoing diagnostic investigations by nuclear medicine methods. METHODS: Calculations are performed on Swedish groups of patients with Paget's disease and with bone metastases from prostatic cancer and diagnosed with bone scintigraphy with an administration of 500 MBq 99mTc-phosphonate. RESULTS: The inclusion of patient survival rates into the calculations lowers the induced radiation cancer risk, as it takes into account that cohorts of patients have shorter predicted survival times than the general population. CONCLUSION: LAR estimations could be valuable for referring physicians, nuclear medicine physicians, nurses, medical physicists, radiologists, and oncologists and as well as ethical committees for risk estimates for specific subgroups of patients. Caution is however advised with respect to application of LAR predictions to individuals (because of individual sensitivities, circumstances, etc.).
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| 16. |
- Andersson, Martin, et al.
(författare)
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ORGAN DOSES AND EFFECTIVE DOSE FOR FIVE PET RADIOPHARMACEUTICALS
- 2016
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 169:1-4, s. 8-253
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Tidskriftsartikel (refereegranskat)abstract
- Diagnostic investigations with positron-emitting radiopharmaceuticals are dominated by (18)F-fluorodeoxyglucose ((18)F-FDG), but other radiopharmaceuticals are also commercially available or under development. Five of them, which are all clinically important, are (18)F-fluoride, (18)F-fluoroethyltyrosine ((18)F-FET), (18)F-deoxyfluorothymidine ((18)F-FLT), (18)F-fluorocholine ((18)F-choline) and (11)C-raclopride. To estimate the potential risk of stochastic effects (mainly lethal cancer) to a population, organ doses and effective dose values were updated for all five radiopharmaceuticals. Dose calculations were performed using the computer program IDAC2.0, which bases its calculations on the ICRP/ICRU adult reference voxel phantoms and the tissue weighting factors from ICRP publication 103. The biokinetic models were taken from ICRP publication 128. For organ doses, there are substantial changes. The only significant change in effective dose compared with previous estimations was a 46 % reduction for (18)F-fluoride. The estimated effective dose in mSv MBq(-1) was 1.5E-02 for (18)F-FET, 1.5E-02 for (18)F-FLT, 2.0E-02 for (18)F-choline, 9.0E-03 for (18)F-fluoride and 4.4E-03 for (11)C-raclopride.
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| 17. |
- Ardenfors, Oscar, et al.
(författare)
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IMPACT OF IRRADIATION SETUP IN PROTON SPOT SCANNING BRAIN THERAPY ON ORGAN DOSES FROM SECONDARY RADIATION
- 2018
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 180:1-4, s. 261-266
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Tidskriftsartikel (refereegranskat)abstract
- A Monte Carlo model of a proton spot scanning pencil beam was used to simulate organ doses from secondary radiation produced from brain tumour treatments delivered with either a lateral field or a vertex field to one adult and one paediatric patient. Absorbed doses from secondary neutrons, photons and protons and neutron equivalent doses were higher for the vertex field in both patients, but the differences were low in absolute terms. Absorbed doses ranged between 0.1 and 43 mu Gy. Gy(-1) in both patients with the paediatric patient receiving higher doses. The neutron equivalent doses to the organs ranged between 0.5 and 141 mu Sv. Gy(-1) for the paediatric patient and between 0.2 and 134 mu Sv. Gy(-1) for the adult. The highest neutron equivalent dose from the entire treatment was 7 mSv regardless of field setup and patient size. The results indicate that different field setups do not introduce large absolute variations in out-of-field doses produced in patients undergoing proton pencil beam scanning of centrally located brain tumours.
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| 18. |
- Arvidsson, Jonathan, et al.
(författare)
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Image Fusion of Reconstructed Digital Tomosynthesis Volumes From a Frontal and a Lateral Acquisition
- 2016
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Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 169:1-4, s. 410-415
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Tidskriftsartikel (refereegranskat)abstract
- Digital tomosynthesis (DTS) has been used in chest imaging as a low radiation dose alternative to computed tomography (CT). Traditional DTS shows limitations in the spatial resolution in the out-of-plane dimension. As a first indication of whether a dual-plane dual-view (DPDV) DTS data acquisition can yield a fair resolution in all three spatial dimensions, a manual registration between a frontal and a lateral image volume was performed. An anthropomorphic chest phantom was scanned frontally and laterally using a linear DTS acquisition, at 120 kVp. The reconstructed image volumes were resampled and manually co-registered. Expert radiologist delineations of the mediastinal soft tissues enabled calculation of similarity metrics in regard to delineations in a reference CT volume. The fused volume produced the highest total overlap, implying that the fused volume was a more isotropic 3D representation of the examined object than the traditional chest DTS volumes.
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| 19. |
- Aslund, Magnus, et al.
(författare)
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Detectors for the future of X-ray imaging
- 2010
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 139:1-3, s. 327-333
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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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| 20. |
- Aurumskjöld, Marie-Louise, et al.
(författare)
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A PHANTOM STUDY SHOWING THE IMPORTANCE OF COMPRESSION IN CONVENTIONAL DIAGNOSTIC X-RAY EXAMINATIONS.
- 2010
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; Apr 7, s. 78-80
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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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| 21. |
- Aurumskjöld, Marie-Louise, et al.
(författare)
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MODEL-BASED ITERATIVE RECONSTRUCTION ENABLES THE EVALUATION OF THIN-SLICE COMPUTED TOMOGRAPHY IMAGES WITHOUT DEGRADING IMAGE QUALITY OR INCREASING RADIATION DOSE.
- 2016
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 169:1-4, s. 100-106
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Tidskriftsartikel (refereegranskat)abstract
- Computed tomography (CT) is one of the most important modalities in a radiological department. This technique not only produces images that enable radiological reports with high diagnostic confidence, but it may also provide an elevated radiation dose to the patient. The radiation dose can be reduced by using advanced image reconstruction algorithms. This study was performed on a Brilliance iCT, equipped with iDose(4) iterative reconstruction and an iterative model-based reconstruction (IMR) method. The purpose was to investigate the effect of reduced slice thickness combined with an IMR method on image quality compared with standard slice thickness with iDose(4) reconstruction. The results of objective and subjective image quality evaluations showed that a thinner slice combined with IMR can improve the image quality and reduce partial volume artefacts compared with the standard slice thickness with iDose(4). In conclusion, IMR enables reduction of the slice thickness while maintaining or even improving image quality versus iDose(4).
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| 22. |
- 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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| 23. |
- Bahar Gogani, Jalil, 1967-, et al.
(författare)
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Assessment of correlated dose and sensitivity profiles on a multi-slice CT scanner
- 2005
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 114:1-3, s. 332-336
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Tidskriftsartikel (refereegranskat)abstract
- In the case of computed tomography (CT) scanners as well as other imaging techniques utilising ionising radiation, it is imperative that radiation is confined to the sensitive part of the image detector. Assuring this for a CT scanner requires detailed information about the scanner dose and sensitivity profiles and their spatial correlation. The profiles should ideally be co-centric and tightly fit to each other. Ensuring this inherent performance of the scanner can be seen as one of the fundamental steps in optimising diagnostic examinations with CT. A measurement device using a dedicated liquid ionisation chamber is employed to investigate the performance of a Toshiba Aquilion 16 scanner in this aspect. Dose profile and sensitivity profile pairs for four collimations are presented where each pair of profiles are spatially correlated to each other. The measurement device can be applied to any scanner for fast and accurate assessment of dose and sensitivity profiles and their spatial correlation. © The Author 2005. Published by Oxford University Press. All rights reserved.
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| 24. |
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| 25. |
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| 26. |
- Bandara, P, et al.
(författare)
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Letter to the Editor
- 2018
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Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 178:3, s. 288-291
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 27. |
- Barufaldi, Bruno, et al.
(författare)
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Virtual Clinical Trials in Medical Imaging System Evaluation and Optimisation
- 2021
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 195:3-4, s. 363-371
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Tidskriftsartikel (refereegranskat)abstract
- Virtual clinical trials (VCTs) can be used to evaluate and optimise medical imaging systems. VCTs are based on computer simulations of human anatomy, imaging modalities and image interpretation. OpenVCT is an open-source framework for conducting VCTs of medical imaging, with a particular focus on breast imaging. The aim of this paper was to evaluate the OpenVCT framework in two tasks involving digital breast tomosynthesis (DBT). First, VCTs were used to perform a detailed comparison of virtual and clinical reading studies for the detection of lesions in digital mammography and DBT. Then, the framework was expanded to include mechanical imaging (MI) and was used to optimise the novel combination of simultaneous DBT and MI. The first experiments showed close agreement between the clinical and the virtual study, confirming that VCTs can predict changes in performance of DBT accurately. Work in simultaneous DBT and MI system has demonstrated that the system can be optimised in terms of the DBT image quality. We are currently working to expand the OpenVCT software to simulate MI acquisition more accurately and to include models of tumour growth. Based on our experience to date, we envision a future in which VCTs have an important role in medical imaging, including support for more imaging modalities, use with rare diseases and a role in training and testing artificial intelligence (AI) systems.
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| 28. |
- Batistoni, P., et al.
(författare)
-
Overview of neutron measurements in jet fusion device
- 2018
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Ingår i: Radiation Protection Dosimetry. - : OXFORD UNIV PRESS. - 0144-8420 .- 1742-3406. ; 180:1-4, s. 102-108
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Tidskriftsartikel (refereegranskat)abstract
- The design and operation of ITER experimental fusion reactor requires the development of neutron measurement techniques and numerical tools to derive the fusion power and the radiation field in the device and in the surrounding areas. Nuclear analyses provide essential input to the conceptual design, optimisation, engineering and safety case in ITER and power plant studies. The required radiation transport calculations are extremely challenging because of the large physical extent of the reactor plant, the complexity of the geometry, and the combination of deep penetration and streaming paths. This article reports the experimental activities which are carried-out at JET to validate the neutronics measurements methods and numerical tools used in ITER and power plant design. A new deuterium-tritium campaign is proposed in 2019 at JET: the unique 14 MeV neutron yields produced will be exploited as much as possible to validate measurement techniques, codes, procedures and data currently used in ITER design thus reducing the related uncertainties and the associated risks in the machine operation.
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| 29. |
- Baverstock, K, et al.
(författare)
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Can a system approach help radiobiology?
- 2011
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Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 143:2-4, s. 536-541
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Tidskriftsartikel (refereegranskat)
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| 30. |
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| 31. |
- Begano, Dino, et al.
(författare)
-
TO USE OR NOT USE PATIENT SHIELDING ON PREGNANT WOMEN UNDERGOING CT PULMONARY ANGIOGRAPHY : A PHANTOM STUDY
- 2020
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 189:4, s. 458-465
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Tidskriftsartikel (refereegranskat)abstract
- Pregnancy increases the risk of pulmonary embolism. Computed tomography pulmonary angiography (CTPA) is used for diagnosis. CT generates ionising radiation, and thus, abdominal shielding may be used. This phantom study investigated the effects of patient shielding and scan length reduction on the fetal and maternal ionising radiation dose from CTPA. The absorbed dose to the fetus was measured using thermoluminescent dosemeters. Estimated effective doses to the pregnant patient were based on the dose-length products. Shielding increased both the effective dose to the patient by 47% and the mean absorbed dose to the fetus (0.10 vs. 0.12 mGy; p < 0.001) compared with unshielded standard CTPA, as it affected the automatic exposure control. Shielded short CTPA marginally lowered only the mean fetal absorbed dose (0.03 vs. 0.02 mGy; p = 0.018). Shortening the scan reduced the fetal absorbed dose most effectively by 70% (0.10 vs. 0.03 mGy; p = 0.006), compared with the standard unshielded scan. Shielding modestly reduces fetal radiation dose but may compromise automatic exposure control, possibly increasing the maternal and fetal radiation dose. Shortening the scan is beneficial, assuming anatomical coverage is secured.
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| 32. |
- Berner, Karin, et al.
(författare)
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Dose optimisation of double-contrast barium enema examinations.
- 2010
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Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 139:1-3, s. 388-392
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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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| 33. |
- Bernitt Cartemo, Petty, 1984, et al.
(författare)
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Comparison of computational phantoms and investigation of the effect of biodistribution on activity estimations
- 2016
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 171:3, s. 358-364
-
Tidskriftsartikel (refereegranskat)abstract
- We have made a comparison between two computational phantoms, modeled from the unified phantom UPh-08T, for whole-body counting applications. One of these was further compared with the ICRP reference adult male computational phantom. The simulations that were performed for the comparison of all three voxel phantoms use various distributions of 60Co. The two voxel phantoms of the UPh-08T showed good agreement, despite different methods of phantom modeling. Also, effects on efficiency of the inhomogeneous distribution of a radionuclide in the computational UPh-08T phantom were studied, using the realistic biodistribution of 140La. Our results show that the activity estimation of radionuclides, which are inhomogeneously distributed in the human body, will be in error if a homogeneous distribution is assumed for the calibration of whole-body counting systems.
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| 34. |
- Bilski, P., et al.
(författare)
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The problems associated with the monitoring of complex workplace radiation fields at European high-energy accelerators and thermonuclear fusion facilities
- 2007
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 126:1-4, s. 491-496
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Tidskriftsartikel (refereegranskat)abstract
- The European Commission is funding within its Sixth Framework Programme a three-year project (2005-2007) called CONRAD, COordinated Network for RAdiation Dosimetry. The organisational framework for this project is provided by the European Radiation Dosimetry Group EURADOS. One task within the CONRAD project, Work Package 6 (WP6), was to provide a report outlining research needs and research activities within Europe to develop new and improved methods and techniques for the characterisation of complex radiation fields at workplaces around high-energy accelerators, but also at the next generation of thermonuclear fusion facilities. The paper provides an overview of the report, which will be available as CERN Yellow Report.
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| 35. |
- Blomgren, Jan
(författare)
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Fast neutron beams - Prospects for the coming decade
- 2007
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 126:1-4, s. 64-68
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Tidskriftsartikel (refereegranskat)abstract
- The present status of neutron beam production techniques above 20 MeV is discussed. Presently, two main methods are used; white beams and quasi-monoenergetic beams. The performances of these two techniques are discussed, as well as the use of such facilities for measurements of nuclear data for fundamental and applied research. Recently, two novel ideas on how to produce extremely intense neuton beams in the 100-500 MeV range have been proposed. Decay in flight of beta delayed neutron-emitting nuclei could provide beam intensities five orders of magnitudes larger than present facilities. A typical neutron energy spectrum would be essentially monoenergetic, i.e., the energy spread is about 1 MeV with essentially no lowenergy tail. A second option would be to produce beams of He-6 and dissociate the 6 He nuclei into alpha particles and neutrons. The basic features of these concepts are outlined, and the potential for improved nuclear data research is discussed.
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| 36. |
- Blomgren, Jan, et al.
(författare)
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Progress in Dosimetry of Neutrons and Light Nuclei
- 2007
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 126:1-4, s. 1-2
-
Forskningsöversikt (övrigt vetenskapligt/konstnärligt)
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| 37. |
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| 38. |
- Borota, Ljubisa, et al.
(författare)
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Spot Region of Interest Imaging : A Novel Functionality Aimed at X-Ray Dose Reduction in Neurointerventional Procedures
- 2020
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 188:3, s. 322-331
-
Tidskriftsartikel (refereegranskat)abstract
- AIM OF THE STUDY: The aim of this study was to describe a new functionality aimed at X-ray dose reduction, referred to as spot region of interest (Spot ROI) and to compare it with existing dose-saving functionalities, spot fluoroscopy (Spot F), and conventional collimation (CC).MATERIAL AND METHODS: Dose area product, air kerma, and peak skin dose were measured for Spot ROI, Spot F, and CC in three different fields of view (FOVs) 20 × 20 cm, 15 × 15 cm, and 11 × 11 cm using an anthropomorphic head phantom RS-230T. The exposure sequence was 5 min of pulsed fluoroscopy (7.5 pulses per s) followed by 7× digital subtraction angiography (DSA) runs with 30 frames per DSA acquisition (3 fps × 10 s). The collimation in Spot F and CC was adjusted such that the size of the anatomical area exposed was as large as the Spot ROI area in each FOV.RESULTS: The results for all FOVs were the following: for the fluoroscopy, all measured parameters for Spot ROI and Spot F were lower than corresponding values for CC. For DSA and DSA plus fluoroscopy, all measured parameters for Spot ROI were lower than corresponding parameters for Spot F and CC.CONCLUSION: Spot ROI is a promising dose-saving technology that can be applied in fluoroscopy and acquisition. The biggest benefit of Spot ROI is its ability to keep the entire FOV information always visible.
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| 39. |
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| 40. |
- Boson, Jonas, 1976-, et al.
(författare)
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Uncertainty in HPGe detector calibrations for in situ gamma-ray spectrometry
- 2009
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press. - 0144-8420 .- 1742-3406. ; 134:2, s. 122-129
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Tidskriftsartikel (refereegranskat)abstract
- Semi-empirical methods are often used for efficiency calibrations of in situ gamma-ray spectrometry measurements with high-purity germanium detectors. The intrinsic detector efficiency is experimentally determined for different photon energies and angles of incidence, and a suitable expression for the efficiency is fitted to empirical data. In this work, the combined standard uncertainty of such an efficiency function for two detectors was assessed. The uncertainties in individual efficiency measurements were found to be about 1.9 and 3.1% (with a coverage factor k = 1, i.e. with a confidence interval of about 68%) for the two detectors. The main contributions to these uncertainties were found to originate from uncertainties in source-to-detector distance, source activity and full-energy peak count rate. The standard uncertainties of the fitted functions were found to be somewhat higher than the uncertainty of individual data points, i.e. 5.2 and 8.1% (k = 1). With the introduction of a new expression for the detector efficiency, these uncertainties were reduced to 3.7 and 4.2%, i.e. with up to a factor of two. Note that this work only addresses the uncertainty in the determination of intrinsic detector efficiency.
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| 41. |
- Brehwens, Karl, et al.
(författare)
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A new device to expose cells to changing dose rates of ionising radiation
- 2012
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press. - 0144-8420 .- 1742-3406. ; 148:3, s. 366-371
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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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| 42. |
- Brockstedt, Sara, et al.
(författare)
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BE AWARE OF NEUTRONS OUTSIDE SHORT MAZES FROM 10-MV LINEAR ACCELERATORS X-RAYS IN RADIOTHERAPY FACILITIES.
- 2015
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 165:1-4, s. 464-467
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Tidskriftsartikel (refereegranskat)abstract
- During the radiation survey of a reinstalled 10-MV linear accelerator in an old radiation treatment facility, high dose rates of neutrons were observed. The area outside the maze entrance is used as a waiting room where patients, their relatives and staff other than those involved in the actual treatment can freely pass. High fluence rates of neutrons would cause an unnecessary high effective dose to the staff working in the vicinity of such a system, and it can be several orders higher than the doses received due to X-rays at the same location. However, the common knowledge appears to have been that the effect of neutrons at 10-MV X-ray linear accelerator facilities is negligible and shielding calculations models seldom mention neutrons for this operating energy level. Although data are scarce, reports regarding this phenomenon are now emerging. For the future, it is advocated that contributions from neutrons are considered already during the planning stage of new or modified facilities aimed for 10 MV and that estimated dose levels are verified.
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| 43. |
- Båth, Magnus, 1974, et al.
(författare)
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A conceptual optimisation strategy for radiography in a digital environment.
- 2005
-
Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 114:1-3, s. 230-5
-
Tidskriftsartikel (refereegranskat)abstract
- Using a completely digital environment for the entire imaging process leads to new possibilities for optimisation of radiography since many restrictions of screen/film systems, such as the small dynamic range and the lack of possibilities for image processing, do not apply any longer. However, at the same time these new possibilities lead to a more complicated optimisation process, since more freedom is given to alter parameters. This paper focuses on describing an optimisation strategy that concentrates on taking advantage of the conceptual differences between digital systems and screen/film systems. The strategy can be summarised as: (a) always include the anatomical background during the optimisation, (b) perform all comparisons at a constant effective dose and (c) separate the image display stage from the image collection stage. A three-step process is proposed where the optimal setting of the technique parameters is determined at first, followed by an optimisation of the image processing. In the final step the optimal dose level-given the optimal settings of the image collection and image display stages-is determined.
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| 44. |
- Båth, Magnus, 1974, et al.
(författare)
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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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| 45. |
- 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
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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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| 46. |
- Båth, Magnus, 1974, et al.
(författare)
-
Method of simulating dose reduction for digital radiographic systems.
- 2005
-
Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 114:1-3, s. 253-9
-
Tidskriftsartikel (refereegranskat)abstract
- The optimisation of image quality vs. radiation dose is an important task in medical imaging. To obtain maximum validity of the optimisation, it must be based on clinical images. Images at different dose levels can then either be obtained by collecting patient images at the different dose levels sought to investigate-including additional exposures and permission from an ethical committee-or by manipulating images to simulate different dose levels. The aim of the present work was to develop a method of simulating dose reduction for digital radiographic systems. The method uses information about the detective quantum efficiency and noise power spectrum at the original and simulated dose levels to create an image containing filtered noise. When added to the original image this results in an image with noise which, in terms of frequency content, agrees with the noise present in an image collected at the simulated dose level. To increase the validity, the method takes local dose variations in the original image into account. The method was tested on a computed radiography system and was shown to produce images with noise behaviour similar to that of images actually collected at the simulated dose levels. The method can, therefore, be used to modify an image collected at one dose level so that it simulates an image of the same object collected at any lower dose level.
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| 47. |
- Båth, Magnus, 1974, et al.
(författare)
-
Nodule detection in digital chest radiography: effect of anatomical noise.
- 2005
-
Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 114:1-3, s. 109-13
-
Tidskriftsartikel (refereegranskat)abstract
- The image background resulting from imaged anatomy can be divided into those components that are meaningful to the observers, in the sense that they are recognised as separate structures, and those that are not. These latter components (reffered to as anatomical noise) can be removed using a method developed within the RADIUS group. The aim of the present study was to investigate whether the removal of the anatomical noise results in images where lung nodules with lower contrast can be detected. A receiver operating characteristic (ROC) study was therefore conducted using two types of images: clinical chest images and chest images in which the anatomical noise had been removed. Simulated designer nodules with a full-width-at-fifth-maximum of 10 mm but with varying contrast were added to the images. The contrast needed to obtain an area under the ROC curve of 0.80, C0.8, was used as a measure of detectability (a low value of C0.8 represents a high detectability). Five regions of the chest X ray were investigated and it was found that in all regions the removal of anatomical noise led to images with lower C0.8 than the original images. On average, C0.8 was 20% higher in the original images, ranging from 7% (the lateral pulmonary regions) to 41% (the upper mediastinal regions).
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| 48. |
- Båth, Magnus, 1974, et al.
(författare)
-
Nodule detection in digital chest radiography: introduction to the RADIUS chest trial.
- 2005
-
Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 114:1-3, s. 85-91
-
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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| 49. |
- Båth, Magnus, 1974, et al.
(författare)
-
Nodule detection in digital chest radiography: part of image background acting as pure noise.
- 2005
-
Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 114:1-3, s. 102-8
-
Tidskriftsartikel (refereegranskat)abstract
- There are several factors that influence the radiologist's ability to detect a specific structure/lesion in a radiograph. Three factors that are commonly known to be of major importance are the signal itself, the system noise and the projected anatomy. The aim of this study was to determine to what extent the image background acts as pure noise for the detection of subtle lung nodules in five different regions of the chest. A receiver operating characteristic (ROC) study with five observers was conducted on two different sets of images, clinical chest X-ray images and images with a similar power spectrum as the clinical images but with a random phase spectrum, resulting in an image background containing pure noise. Simulated designer nodules with a full-width-at-fifth-maximum of 10 mm but with varying contrasts were added to the images. As a measure of the part of the image background that acts as pure noise, the ratio between the contrast needed to obtain an area under the ROC curve of 0.80 in the clinical images to that in the random-phase images was used. The ratio ranged from 0.40 (in the lateral pulmonary regions) to 0.83 (in the hilar regions) indicating that there was a large difference between different regions regarding to what extent the image background acted as pure noise; and that in the hilar regions the image background almost completely acted as pure noise for the detection of 10 mm nodules.
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| 50. |
- Båth, Magnus, et al.
(författare)
-
OPTIMISATION in X-RAY and MOLECULAR IMAGING 2020
- 2021
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 195:3-4, s. 133-133
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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