| 1. |
- Clausen, Niels, et al.
(författare)
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Similar bleeding phenotype in young children with haemophilia A or B : A cohort study
- 2014
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Ingår i: Haemophilia. - : Wiley. - 1351-8216. ; 20:6, s. 747-755
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Tidskriftsartikel (refereegranskat)abstract
- The bleeding phenotype has been suggested to differ between haemophilia A and B. More knowledge on the bleeding phenotype at initiation of treatment is important to optimize patient care. The aim of this study was to investigate the severity of the bleeding phenotype and the variation in bleeding in children with severe or moderate haemophilia A and B. Consecutive, previously untreated patients with severe or moderate haemophilia A and B (factor VIII or IX activity <0.01 or 0.01-0.05 IU mL-1 respectively) born between January 1st 2000 and January 1st 2010 were included. Primary outcome was severity of bleeding tendency. Secondary outcome was variation in bleeding pattern. A total of 582 patients with severe haemophilia A and 76 with severe haemophilia B did not differ in age at first exposure to clotting factor (0.81 vs. 0.88 years, P = 0.20), age at first bleed (0.82 vs. 0.88 years, P = 0.36), and age at first joint bleed (1.18 vs. 1.20 years, P = 0.59). Patients with moderate haemophilia were older compared to patients with severe haemophilia. In patients with moderate haemophilia there were no clear differences between haemophilia A and B. Severity and variation in bleeding phenotype are similar during the early stage of treatment in patients with severe and moderate haemophilia A and B respectively. The findings imply that children with haemophilia B should be observed and treated as vigilantly as those with haemophilia A.
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| 2. |
- Lundin, Björn, et al.
(författare)
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An MRI scale for assessment of haemophilic arthropathy from the International Prophylaxis Study Group.
- 2012
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Ingår i: Haemophilia. - : Wiley. - 1351-8216. ; 18:6, s. 962-970
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Tidskriftsartikel (refereegranskat)abstract
- Evaluation of prophylactic treatment of haemophilia requires sensitive methods. To design and test a new magnetic resonance imaging (MRI) scale for haemophilic arthropathy, two scales of a combined MRI scoring scheme were merged into a single scale which includes soft tissue and osteochondral subscores. Sixty-one joint MRI's of 46 patients with haemophilia were evaluated by four radiologists using the new and older scales. Forty-six of the joints were evaluated using two X-ray scales. For all MRI scores, interreader agreement and correlations with X-ray scores and lifetime number of haemarthroses were analysed. The interreader agreement intraclass correlation coefficient was 0.82, 0.89 and 0.88 for the soft tissue and osteochondral subscores and the total score, as evaluated according to the new MRI scale, compared to 0.80 and 0.89 as for the older scales. The total score and osteochondral subscore according to the new scale, as well as scores according to the older scales were correlated (P < 0.01) with number of haemarthroses (Spearman correlation 0.35-0.68) and with the X-ray scores (Spearman correlation 0.40-0.76), but no correlation (P > 0.05) was found between the soft tissue subscore of the new MRI scale and the X-ray scores. The new MRI scale is simpler to apply than the older and has similar reader reliability and correlation with lifetime number of haemarthroses, and by separating soft tissue and osteochondral changes it gives additional information. The new scale is useful for analyses of early and moderate stages of arthropathy, and may help to evaluate prophylactic haemophilia treatment.
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| 3. |
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| 4. |
- Beaulieu, Luc, et al.
(författare)
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Report of the Task Group 186 on model-based dose calculation methods in brachytherapy beyond the TG-43 formalism : Current status and recommendations for clinical implementation
- 2012
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Ingår i: Medical physics (Lancaster). - : American Association of Physicists in Medicine. - 0094-2405. ; 39:10, s. 6208-6236
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Tidskriftsartikel (refereegranskat)abstract
- The charge of Task Group 186 (TG-186) is to provide guidance for early adopters of model-based dose calculation algorithms (MBDCAs) for brachytherapy (BT) dose calculations to ensure practice uniformity. Contrary to external beam radiotherapy, heterogeneity correction algorithms have only recently been made available to the BT community. Yet, BT dose calculation accuracy is highly dependent on scatter conditions and photoelectric effect cross-sections relative to water. In specific situations, differences between the current water-based BT dose calculation formalism (TG-43) and MBDCAs can lead to differences in calculated doses exceeding a factor of 10. MBDCAs raise three major issues that are not addressed by current guidance documents: (1) MBDCA calculated doses are sensitive to the dose specification medium, resulting in energy-dependent differences between dose calculated to water in a homogeneous water geometry (TG-43), dose calculated to the local medium in the heterogeneous medium, and the intermediate scenario of dose calculated to a small volume of water in the heterogeneous medium. (2) MBDCA doses are sensitive to voxel-by-voxel interaction cross sections. Neither conventional single-energy CT nor ICRU∕ICRP tissue composition compilations provide useful guidance for the task of assigning interaction cross sections to each voxel. (3) Since each patient-source-applicator combination is unique, having reference data for each possible combination to benchmark MBDCAs is an impractical strategy. Hence, a new commissioning process is required. TG-186 addresses in detail the above issues through the literature review and provides explicit recommendations based on the current state of knowledge. TG-43-based dose prescription and dose calculation remain in effect, with MBDCA dose reporting performed in parallel when available. In using MBDCAs, it is recommended that the radiation transport should be performed in the heterogeneous medium and, at minimum, the dose to the local medium be reported along with the TG-43 calculated doses. Assignments of voxel-by-voxel cross sections represent a particular challenge. Electron density information is readily extracted from CT imaging, but cannot be used to distinguish between different materials having the same density. Therefore, a recommendation is made to use a number of standardized materials to maintain uniformity across institutions. Sensitivity analysis shows that this recommendation offers increased accuracy over TG-43. MBDCA commissioning will share commonalities with current TG-43-based systems, but in addition there will be algorithm-specific tasks. Two levels of commissioning are recommended: reproducing TG-43 dose parameters and testing the advanced capabilities of MBDCAs. For validation of heterogeneity and scatter conditions, MBDCAs should mimic the 3D dose distributions from reference virtual geometries. Potential changes in BT dose prescriptions and MBDCA limitations are discussed. When data required for full MBDCA implementation are insufficient, interim recommendations are made and potential areas of research are identified. Application of TG-186 guidance should retain practice uniformity in transitioning from the TG-43 to the MBDCA approach.
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