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Träfflista för sökning "WFRF:(Sund M) srt2:(2000-2004)"

Sökning: WFRF:(Sund M) > (2000-2004)

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1.
  • Lanhede, B., et al. (författare)
  • The Influence of Different Technique Factors on Image Quality for Chest Radiographs: Application of the Recent CEC Image Quality Criteria
  • 2000
  • Ingår i: Radiation Protection Dosimetry. - 1742-3406. ; 90:1-2, s. 203-206
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim of the first this work part of the EU-project, Trial I, was to evaluate and possibly improve the CEC image criteria for radiographic chest images. Chest images of healthy volunteers were acquired using different technique factors. The image criteria were used as a tool to discriminate between the different images. The technique factors were chosen so that the image quality would differ slightly. Four different technique parameters, each with two possible settings, used in clinical practice today, were used: tube voltage - 102 and 141 kV; screen/film speed - 160 and 320; maximum optical density in the parenchyma - 1.3 and 1.8; method for scatter reduction - air gap 30/390 and moving grid40/12. The results showed that the image criteria were able to separate between different technique groups. Some conclusions can be drawn from the results Optical density 1.8 was better than 1.3 independent of the other parameters. . Among the six combinations ranked best , four used tube voltage 141 kV and four used air gap technique for scatter reduction. No difference was seen for screen/film speed. No correlation was seen between the ranking of the systems and patient dose.
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2.
  • Lanhede, B, et al. (författare)
  • The influence of different technique factors on image quality of chest radiographs as evaluated by modified CEC image quality criteria.
  • 2002
  • Ingår i: The British journal of radiology. - : British Institute of Radiology. - 0007-1285 .- 1748-880X. ; 75:889, s. 38-49
  • Tidskriftsartikel (refereegranskat)abstract
    • The Commission of the European Communities (CEC) research project "Predictivity and optimisation in medical radiation protection" addressed fundamental operational limitations in existing radiation protection mechanisms. The first part of the project aimed at investigating (1) whether the CEC image quality criteria could be used for optimization of a radiographic process and (2) whether significant differences in image quality based on these criteria could be detected in a controlled project with well known physical and technical parameters. In the present study, chest radiographs on film were produced using healthy volunteers. Four physical/technical parameters were varied in a carefully controlled manner: tube voltage (102 kVp and 141 kVp), nominal speed class (160 and 320), maximum film density (1.3 and 1.8) and method of scatter reduction (grid (R=12) and air gap). The air kerma at the entrance surface was measured for all patients and the risk-related dose H(Golem), based on calculated organ-equivalent dose conversion coefficients and the measured entrance air kerma values, was calculated. Image quality was evaluated by a group of European expert radiologists using a modified version of the CEC quality criteria. For the two density levels, density level 1.8 was significantly better than 1.3 but at the cost of a higher patient radiation exposure. The correlation between the number of fulfilled quality criteria and H(Golem) was generally poor. An air gap technique resulted in lower doses than scatter reduction with a grid but provided comparable image quality. The criteria can be used to highlight optimum radiographic technique in terms of image quality and patient dose, although not unambiguously. A recommendation for good radiographic technique based on a compromise between image quality and risk-related radiation dose to the patient is to use 141 kVp, an air gap, a screen-film system with speed 320 and an optical density of 1.8.
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4.
  • Lowe, Michael R., et al. (författare)
  • The length of the CTLA-4 microsatellite (AT)(N)-repeat affects the risk for type 1 diabetes
  • 2000
  • Ingår i: Autoimmunity. - : Informa UK Limited. - 0891-6934 .- 1607-842X. ; 32:3, s. 173-180
  • Tidskriftsartikel (refereegranskat)abstract
    • CTLA-4 is important to down-regulating T cell responses and has been implicated in type 1 (insulin dependent) diabetes mellitus in both linkage and association studies. The aim of our study was to relate the polymorphic (AT)(n) microsatellite in the 3' untranslated sequence of the CTLA-4 gene to diabetes risk. We studied 616 consecutively diagnosed 0-34 year-old Swedish patients and 502 matched controls by PCR-based genotyping to determine the length of the 3'-end (AT)(n)repeat region of the CTLA-4 gene and categorizing alleles as predominantly monomorphic short (S) or highly polymorphic (in length) long (L) alleles. The odds of type 1 diabetes of subjects with the L/L genotype was estimated to be 1.84 times that of subjects with the S/S genotype (95% CI 1.44-2.73, p=0.002). Further analysis of the long alleles, partitioned into intermediate (I) length and very long (VL) alleles, suggested that L alleles act recessively in conferring diabetes risk (p=0.0009). This study suggests that the 3'-end (AT)(n) repeat region of the CTLA-4 gene represents a recessive risk factor for type 1 diabetes.
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