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  • 1.
    Dance, David
    et al.
    Royal Marsden NHS Trust.
    Lester, Sonia
    n/a.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Care, Radiation Physics. Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, Faculty of Health Sciences.
    Sandborg, Michael
    Linköping University, Department of Medicine and Care, Radiation Physics. Linköping University, Center for Medical Image Science and Visualization, CMIV. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics. Linköping University, Faculty of Health Sciences.
    Persliden, Jan
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    The use of carbon fibre material in radiographic cassettes: estimation of the dose and contrast advantages1997In: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 70, p. 383-390Article in journal (Refereed)
    Abstract [en]

    A Monte Carlo simulation has been used to estimate the dose and contrast advantages of replacing radiographic cassette fronts fabricated from aluminium with cassette fronts fabricated from low atomic number material (carbon fibre). The simulation used a realistic imaging geometry and calculations were made both with and without an anti-scatter grid. Account was taken of the scatter generated in the cassette front and the effect of beam hardening on primary contrast. Dose and contrast were evaluated for a range of cassette front thicknesses and tube potentials (60-150 kV) as well as for four examinations representative of situations with varying amounts of scatter. The results with an anti-scatter grid show a clear dose and contrast advantage in all cases when an aluminium cassette front is replaced with a low attenuation cassette front. The contrast advantage is dependent upon the examination and is generally greater for imaging bony structures than for imaging soft tissue. If a 1.74 mm aluminium cassette front is compared with a 1.1 mm carbon fibre cassette front, then the dose advantages are 16%, 9%, 8% and 6% and the contrast advantages are 10%, 7%, 4% and 5% for the AP paediatric pelvis examination at 60 kV, the anteroposterior (AP) lumbar spine examination at 80 kV, the lateral lumbar spine examination at 100 kV and the posteroanterior (PA) chest examination at 150 kV, respectively. The results without an anti-scatter grid show an increased dose advantage when a low attenuation cassette front is used, but the contrast advantage is small and in some situations negative.

  • 2. Dance, David
    et al.
    Thilander Klang, Anne
    Sandborg, Michael
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radio Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Skinner, Claire
    Castellano Smith, Isabelle
    Alm Carlsson, Gudrun
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radio Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Influence of anode/filter material and tube potential on contrast, signal-to-noise ratio and average absorbed dose in mammography: a Monte Carlo study.2000In: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 76, p. 1056-1067Article in journal (Refereed)
  • 3.
    Dasu, Alexandru
    et al.
    Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences.
    Toma-Dasu, Iuliana
    Stockholm University.
    Will intrafraction repair have negative consequences on extreme hypofractionation in prostate radiation therapy?2015In: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 88, no 1056, p. Article ID 20150588-Article in journal (Refereed)
    Abstract [en]

    Objective: The aim of the present study was to investigate the impact of increasing fraction delivery time on the outcome of hypofractionated radiation therapy for prostate cancer.

    Methods: Monoexponential and biexponential repair models have been used for patients with prostate cancer to study the loss of biochemical control at 5 years for several clinically relevant irradiation times. The theoretical predictions were compared with newly reported clinical results from 4607 patients undergoing conventionally fractionated and hypofractionated prostate radiation therapy.

    Results: Time-demanding irradiation techniques appear to lead to biochemical control rates that sometimes are about 10–20 percentage points below predictions that neglect intrafraction repair. This difference appears to be of the same order of magnitude as that predicted by moderately slow to slow repair taking place during the irradiation time. The impact is largest for the patient risk groups receiving doses corresponding to the steepest part of the dose–response curve. By contrast, for treatment techniques requiring irradiation times shorter than about 20 min, the impact of intrafraction repair appears to be much smaller and probably difficult to be observed in the light of other sources of uncertainty in clinical data.

    Conclusion: Neglecting intrafraction repair might overestimate the effectiveness of some treatment schedules and could also influence any subsequent estimations of fractionation sensitivity for prostate tumours.

    Advances in knowledge: The effect of intrafraction repair for prostate cancer should be taken into account for long irradiation sessions as might be expected from scanned beams and/or from multiple intrafraction imaging sessions to check the positioning of the patient.

  • 4.
    Jansson, Margareta
    et al.
    Department of Radiology, Örebro University Hospital, Örebro, Sweden.
    Geijer, Håkan
    Department of Radiology, Örebro University Hospital, Örebro, Sweden.
    Andersson, Torbjörn
    Department of Radiology, Örebro University Hospital, Örebro, Sweden.
    Bowel preparation for excretory urography is not necessary: a randomized trial2007In: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 80, no 956, p. 617-624Article in journal (Refereed)
    Abstract [en]

    Despite the fact that computed tomography is becoming more commonly used to investigate the genitourinary tract, intravenous urography still plays an important role in uroradiology. The aim of this study was to compare bowel purgation and two other preparation methods — dietary restrictions and no preparations at all — in an attempt to find the optimal procedure for uniform practice. 210 consecutive patients were randomised to three preparation groups with 70 in each group. Group 1 received standard bowel purgation, Group 2 was instructed to fast, while Group 3 had no preparation at all. Irrespective of preparation, all patients underwent the same examination procedure. The examining radiographer and evaluating radiologists were unaware of the type of preparation given. Image quality was assessed according to European Commission criteria for excretory urography. The effectiveness of bowel purgation and the amount of residual gas were scored separately. There was no statistically significant difference in the proportions with fulfilled criteria between preparation Groups 1 and 2 and Groups 1 and 3. A criterion was regarded as fulfilled only when all three observers agreed. Assessment of the amount of residual faeces proved the effectiveness of our standard bowel purgation. The results of our study show equality of the evaluated preparation methods and cannot justify further use of bowel purgation before excretory urography.

  • 5. McVey, Graham
    et al.
    Sandborg, Michael
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radio Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Dance, David
    Alm Carlsson, Gudrun
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radio Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    A study and optimization of lumbar spine X-ray imaging systems2003In: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 76, no 903, p. 177-188Article in journal (Refereed)
    Abstract [en]

    A Monte Carlo program has been developed that incorporates a voxel phantom of an adult patient in a model of the complete X-ray imaging system, including the anti-scatter grid and screen-film receptor. This allows the realistic estimation of patient dose and the corresponding image (optical density map) for a wide range of equipment configurations. This paper focuses on the application of the program to lumbar spine anteroposterior and lateral screen-film examinations. The program has been applied to study the variation of physical image quality measures and effective dose for changing system parameters such as tube voltage, grid design and screen-film system speed. These variations form the basis for optimization of these system parameters. In our approach to optimization, the best systems are those that can match (or come close to) the calculated image quality measure of systems preferred in a recent European clinical trial, but with lower patient dose. The largest dose savings found were 21% for a 400 speed class system with a grid having a strip density of 40 cm-1 and a grid ratio of 16. A further dose saving of 13% was possible when a 600 speed class system was employed. The best systems found from the optimization correspond to those recommended by the European Commission guidelines on image quality criteria for diagnostic radiographic images.

  • 6.
    Persson, Anders
    et al.
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Medical Radiology. Östergötlands Läns Landsting, Centre for Medical Imaging, Department of Radiology in Linköping.
    Dahlström, Nils
    Department of Radiology, Hudiksvall Hospital, Sweden.
    Smedby, Örjan
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radiation Physics. Östergötlands Läns Landsting, Center for Diagnostics, Department of Radiology in Linköping.
    Brismar, T.B.
    Department of Radiology, Karolinska University Hospital, Huddinge, Stockholm, Sweden .
    Volume rendering of three-dimensional drip infusion CT cholangiography in patients with suspected obstructive biliary disease: a retrospective study2005In: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 78, no 936, p. 1078-1085Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to evaluate the diagnostic potential of prolonged drip infusion CT cholangiography (DIC-CT) using meglumine iotroxate (Biliscopin®) and 3D volume rendering in patients with suspected obstructive biliary disease. From a material of 142 patients who had undergone a drip infusion CT, all cases with a verified surgical or endoscopic retrograde cholangiography (ERC) diagnosis (n=33) were selected. Age-matched controls were selected from the remaining examinations. Three radiologists reviewed all 66 examinations in retrospect, independently as well as in consensus. The image quality and the estimated diagnostic quality were rated as good or moderate in 91% of the 198 reviews. The consensus sensitivity and specificity for diagnosing biliary stones was 88% and 94%, respectively (with sensitivities ranging from 88% to 94% for individual observers, and specificities from 86% to 96%). Two out of three strictures were observed. No false positive strictures were described. The use of volume rendering technique (VRT) improved diagnostic certainty in 28/198 (14%) of the evaluations. The visualization of ductal stones was improved in 18/48 (38%). No differences in diagnostic quality between single and multislice CT were observed. We conclude that a detailed image of the biliary tree with good sensitivity and specificity can be obtained by means of bilirubin-governed infusion time DIC-CT with volume rendering reconstruction.

  • 7.
    Pettersson, Håkan
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Fälth-Magnusson, Karin
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Pediatrics . Östergötlands Läns Landsting, Centre of Paediatrics and Gynecology and Obstetrics, Department of Paediatrics in Linköping.
    Persliden, Jan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Scott, M.
    Department of Statistics, University of Glasgow, Glasgow G12 8QW, United Kingdom.
    Radiation risk and cost-benefit analysis of a paediatric radiology procedure: Results from a national study2005In: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 78, no 925, p. 34-38Article in journal (Refereed)
    Abstract [en]

    A national study was performed to investigate radiation doses and associated risks to patients during X-ray fluoroscopy-guided small intestinal biopsies in the investigation of coeliac disease. Thermoluminescent dosemeters (TLD) and questionnaires were sent to 42 of the 43 paediatric departments in Sweden performing these biopsies. During the study period (2 × 3 weeks) 257 biopsies were recorded, representing about 10% of annually performed paediatric investigations. The results show that the absorbed dose during biopsy ranged from 0.04 mGy to 23.8 mGy (mean 1.87 mGy). The fluoroscopy time ranged from 2 s to 663 s (mean 60 s). The collective dose from the procedure amounts to 4.7 manSv year-1. Thus, the annual excess cancer mortality, including severe hereditary effects, can be estimated at 0.6-0.7 cases per year. However, significant dose saving can be obtained by proper choice of sedation and biopsy equipment. © 2005 The British Institute of Radiology.

  • 8.
    Sandborg, Michael
    et al.
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Center for Medical Image Science and Visualization, CMIV. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics. Linköping University, Faculty of Health Sciences.
    Dance, David
    n/a.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, Faculty of Health Sciences.
    Persliden, Jan
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Monte Carlo study of grid performance in diagnostic radiology: factors which affect the selection of tube potential and grid ratio1993In: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 66, p. 1164-1176Article in journal (Refereed)
    Abstract [en]

    A Monte Carlo computational model has been developed for the study of the performance of anti-scatter grids in diagnostic radiology. It is used here to estimate the scatter in the image plane from soft tissue phantoms (representing the patient) and to calculate image contrast and the mean absorbed dose in the phantom. Different scattering conditions, representative of various examinations, have been investigated: adult lumbar spine; small field radiography and fluoroscopy; adult chest and paediatric pelvis and chest. For each scattering condition, the combinations of tube potential and grid ratio have been found which, for a well designed grid, result in the lowest mean absorbed dose in the phantom for a fixed contrast level. In examinations which generate large amounts of scatter, the use of high grid ratios in combination with high tube potentials is favourable with regard to both mean absorbed dose in the phantom and tube charge. When less scatter is generated, either the grid ratio or the tube potential can be varied to achieve the desired contrast level. High grid ratios require shorter exposure times, but need careful alignment in the beam to prevent primary radiation cut-off. It is shown that the air gap technique can be used to reduce patient dose in examinations with small amounts of scatter, but in combinations with a lower tube potential than when a grid is used.

  • 9.
    Sandborg, Michael
    et al.
    Linköping University, Department of Medicine and Care, Radiation Physics. Linköping University, Center for Medical Image Science and Visualization, CMIV. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics. Linköping University, Faculty of Health Sciences.
    Dance, David
    The Royal Marsden Hospital.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Persliden, Jan
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Monte Carlo study of grid performance in diagnostic radiology: task dependent opti­misation for screen-film imaging1994In: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 67, p. 76-85Article in journal (Refereed)
    Abstract [en]

    An optimization of anti-scatter grid design using Monte Carlo techniques in diagnostic radiology is presented. The criterion for optimization was to find the combinations of the grid parameters (lead strip width, grid ratio and strip density) and tube potential which result in the lowest mean absorbed dose in the patient at fixed image contrast. The optimization was performed in three irradiation geometries, representing different scattering conditions (paediatric examinations, and two adult lumbar spine examinations) and was restricted to grids using fibre materials in covers and interspaces. Grid designs currently available were studied, as were designs which use thinner strips (< 30 µm) and higher grid ratios (> 18). It was found that grids with widely different strip densities (strips cm–1) and grid ratios can have good performance provided that they are used with appropriate strip width and tube potential. With increasing amounts of scatter, the optimal grid requires thicker strips and higher grid ratios. Increasing the strip density and using thinner strips and higher grid ratios are generally required. Grids with low strip density (25 strips cm–1) were found to be less sensitive to alterations in strip width. Optimal grids for paediatric radiology require thinner strips (10–20 µm) than those in currently available grids. Grids on the market are best suited for examinations of the adult body in anteroposterior (AP) view. In the adult lateral view, representing the largest scattering volume, higher grid ratios (> 18) than those in existing grids would be optimal. Examples of good grid designs are given for each examination.

  • 10.
    Sandborg, Michael
    et al.
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Center for Medical Image Science and Visualization, CMIV. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics. Linköping University, Faculty of Health Sciences.
    Dance, David
    n/a.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Center for Medical Image Science and Visualization, CMIV. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics. Linköping University, Faculty of Health Sciences.
    Persliden, Jan
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Selection of anti-scatter grids for different imaging tasks: the advantage of low atomic number cover and interspace materials1993In: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 66, p. 1151-1163Article in journal (Refereed)
    Abstract [en]

    A Monte Carlo computer program has been developed for the study of anti-scatter grids used in diagnostic radiology. The program estimates the scatter from soft tissue phantoms representative of either adult or paediatric examinations and uses dose increase, signal-to-noise ratio improvement and contrast improvement factors to study grid performance. It has been used to quantify the advantage of replacing grids with aluminium covers and interspaces by grids using materials of low atomic number for these components. Two approaches are used. First, the aluminium and low atomic number alternatives are compared for five grid ratios at fixed strip density and width and for tube potentials of 50, 70, 100 and 150 kV. Second, 44 commercially available grids are compared for three different imaging situations (lumbar spine, chest and paediatric). The results demonstrate that grids made with carbon fibre cover and cotton fibre interspace result in greater improvements in contrast and signal-to-noise ratio, and lower dose increase factors, than do grids made with aluminium. The dose reduction varies with irradiation conditions and is generally larger at lower tube potentials, higher grid ratios and lower strip densities. A typical reduction in mean absorbed dose in the patient is 30% in an adult lumbar spine (AP view) at 70 kV with a grid with 36 strips per centimetre and ratio 12.

  • 11.
    Sandborg, Michael
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radio Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Tingberg, Anders
    Dance, David
    Lanhede, Birgitta
    Almén, Anja
    Mc Vey, Graham
    Sund, Patrick
    Besjakow, Jack
    Mattson, Sören
    Månsson, Lars-Gunnar
    Alm Carlsson, Gudrun
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radio Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Demonstration of correlations between clinical and physical image quality measures in chest and lumbar spine screen-film radiography2001In: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 74, no 882, p. 520-528Article in journal (Refereed)
    Abstract [en]

    The ability to predict clinical image quality from physical measures is useful for optimization in diagnostic radiology. In this work, clinical and physical assessments of image quality are compared and correlations between the two are derived. Clinical assessment has been made by a group of expert radiologists who evaluated fulfilment of the European image criteria for chest and lumbar spine radiography using two scoring methods: image criteria score (ICS) and visual grading analysis score (VGAS). Physical image quality measures were calculated using a Monte Carlo simulation model of the complete imaging system. This model includes a voxelized male anatomy and was used to calculate contrast and signal-to-noise ratio of various important anatomical details and measures of dynamic range. Correlations between the physical image quality measures on the one hand and the ICS and VGAS on the other were sought. 16 chest and 4 lumbar spine imaging system configurations were compared in frontal projection. A statistically significant correlation with clinical image quality was found in chest posteroanterior radiography for the contrast of blood vessels in the retrocardiac area and a measure of useful dynamic range. In lumbar spine anteroposterior radiography, a similar significant correlation with clinical image quality was found between the contrast and signal-to-noise ratio of the trabecular structures in the L1-L5 vertebrae. The significant correlation shows that clinical image quality can, at least in some cases, be predicted from appropriate measures of physical image quality.

  • 12.
    Smedby, Örjan
    et al.
    Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, Department of Medicine and Health Sciences, Radiology . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Medical Imaging, Department of Radiology in Linköping.
    Fredrikson, Mats
    Linköping University, Department of Clinical and Experimental Medicine, Occupational and Environmental Medicine . Linköping University, Faculty of Health Sciences.
    Visual grading regression: analysing data from visual grading experiments with regression models2010In: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 83, no 993, p. 767-775Article in journal (Refereed)
    Abstract [en]

    For visual grading experiments, which are an easy and increasingly popular way of studying image quality, hitherto used data analysis methods are often inadequate. Visual grading analysis makes assumptions that are not statistically appropriate for ordinal data, and visual grading characteristic curves are difficult to apply in more complex experimental designs. The approach proposed in this paper, visual grading regression (VGR), consists of an established statistical technique, ordinal logistic regression, applied to data from single-image and image-pair experiments with visual grading scores selected on an ordinal scale. The approach is applicable for situations in which, for example, the effects of the choice of imaging equipment and post-processing method are to be studied simultaneously, while controlling for potentially confounding variables such as patient and observer identity. The analysis can be performed with standard statistical software packages using straightforward coding of the data. We conclude that the proposed statistical technique is useful in a wide range of visual grading studies.

  • 13.
    Smedby, Örjan
    et al.
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Radiology in Linköping.
    Fredrikson, Mats
    Linköping University, Department of Clinical and Experimental Medicine, Occupational and Environmental Medicine. Linköping University, Faculty of Health Sciences.
    de Geer, Jakob
    Linköping University, Department of Medical and Health Sciences, Radiology. Linköping University, Faculty of Health Sciences.
    Borgen, L
    Drammen Hospital, Norway .
    Sandborg, Michael
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Quantifying the potential for dose reduction with visual grading regression2013In: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 86, no 1021Article in journal (Refereed)
    Abstract [en]

    Objectives To propose a method to study the effect of exposure settings on image quality and to estimate the potential for dose reduction when introducing dose-reducing measures.

    Methods Using the framework of visual grading regression (VGR), a log(mAs) term is included in the ordinal logistic regression equation, so that the effect of reducing the dose can be quantitatively related to the effect of adding post-processing. In the ordinal logistic regression, patient and observer identity are treated as random effects using generalised linear latent and mixed models. The potential dose reduction is then estimated from the regression coefficients. The method was applied in a single-image study of coronary CT angiography (CTA) to evaluate two-dimensional (2D) adaptive filters, and in an image-pair study of abdominal CT to evaluate 2D and three-dimensional (3D) adaptive filters.

    Results For five image quality criteria in coronary CTA, dose reductions of 16–26% were predicted when adding 2D filtering. Using five image quality criteria for abdominal CT, it was estimated that 2D filtering permits doses were reduced by 32–41%, and 3D filtering by 42–51%.

    Conclusions VGR including a log(mAs) term can be used for predictions of potential dose reduction that may be useful for guiding researchers in designing subsequent studies evaluating diagnostic value. With appropriate statistical analysis, it is possible to obtain direct numerical estimates of the dose-reducing potential of novel acquisition, reconstruction or post-processing techniques.

  • 14. Tingberg, A
    et al.
    Herrmann, C
    Lanhede, B
    Almen, A
    Sandborg, Michael
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radiation Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    McVey, G
    Mattsson, S
    Panzer, W
    Besjakov, J
    Månsson, LG
    Kheddache, S
    Alm-Carlsson, Gudrun
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radiation Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Dance, DR
    Tylen, U
    Zankl, M
    Influence of the characteristic curve on the clinical image quality of lumbar spine and chest radiographs2004In: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 77, no 915, p. 204-215Article in journal (Refereed)
    Abstract [en]

    The "European Guidelines on Quality Criteria for Diagnostic Radiographic Images" do not address the choice of the film characteristic (H&D) curve, which is an important parameter for the description of a radiographic screen-film system. The image contrast of clinical lumbar spine and chest radiographs was altered by digital image processing techniques, simulating images with different H&D curves, both steeper and flatter than the original. The manipulated images were printed on film for evaluation. Seven experienced radiologists evaluated the clinical image quality by analysing the fulfilment of the European Image Criteria (ICS) and by visual grading analysis (VGA) of in total 224 lumbar spine and 360 chest images. A parallel study of the effect of the H&D curve has also been made using a theoretical model. The contrast (ΔOD) of relevant anatomical details was calculated, using a Monte Carlo simulation-model of the complete imaging system including a 3D voxel phantom of a patient. Correlations between the calculated contrast and the radiologists' assessment by VGA were sought. The results of the radiologists' assessment show that the quality in selected regions of lumbar spine and chest images can be significantly improved by the use of films with a steeper H&D curve compared with the standard latitude film. Significant (p<0.05) correlations were found between the VGA results and the calculations of the contrast of transverse processes and trabecular details in the lumbar spine vertebrae, and with the contrast of blood vessels in the retrocardiac area of the chest.

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