The aim of this study was to obtain the traceability of the software used to analyze lateral cephalometry and to calculate the uncertainty of the measurements. Furthermore, this study aimed to provide a basis for obtaining standard references for measurement values for orthodontic treatment in children. Cephalometric data were collected from 100 children diagnosed with class I malocclusion between the ages 6 to 13 years who visited the pediatric dentist at Seoul National University Dental Hospital. To ensure traceability, a phantom device was created. Correction values were calculated by measuring the length and angle of the phantom device using the software. Type A uncertainty was calculated by obtaining the standard deviation of cephalometric measurements of 100 persons and the standard error of repeated measurements. Determination of the type B uncertainty was induced by minimum resolution and the position of the head. Using these, the combined standard uncertainty was obtained and the expanded uncertainty was calculated. The results of this study confirm that the currently used software has high accuracy and reliability. Furthermore, the uncertainty of orthodontic measurements in Korean children aged 6 to 13 years was calculated, and distribution range for class I malocclusion with 95% confidence interval was suggested.
Acquired hemophilia A (AHA) is a rare hemorrhagic disorder caused by autoantibodies against factor VIII (FVIII). An 80-year-old woman presented multiple bruises on her upper and lower extremities, along with gross hematuria. Extensive ecchymosis and swelling were observed on the buttocks. She had anemia and normal platelet count. The initial coagulation results showed prolonged activated partial thromboplastin time (aPTT, 68.5 seconds) and normal prothrombin time. According to the mixing test, we observed a decreased FVIII activity (2%), increased factor VIII inhibitor (FVIII-I) titer (74.4 BU), and negative lupus anticoagulant. AHA was diagnosed based on late onset bleeding and increased FVIII-I titer. Additionally, she met the criteria for systemic lupus erythematosus (oral ulcer, photosensitivity, renal disorder, and positivity for antinuclear and anti-β2-glycoprotein-I antibodies). She was started on oral prednisolone for FVIII-I eradication. Post-treatment, her bleeding tendency, aPTT (47.3 seconds), and FVIII-I titer decreased (1.24 BU), and FVIII activity increased (10%). (J Rheum Dis 2017;24:309-312)
Background The characteristics of the multileaf collimator (MLC) position error were investigated without clinical variability and other factors affecting the error analysis. An index indicating the attributes of MLC position error was found and used for MLC position error prediction model. The dose-volume histogram (DVH) was examined to investigate the clinical relationship.Methods: The dose distribution was investigated using the gamma index, structural similarity (SSIM) index, and dosiomics index. The cases from the American Association of Physicists in Medicine Task Group 119 were planned, and systematic and random MLC position errors were simulated. All error-free and error datasets were generated in the treatment plan system. The indices were obtained from distribution maps, and then statistically significant indices were selected. An MLC position error prediction model was developed using the selected indices and logistic regression method. The final model was determined when all values of the area under the curve (AUC), accuracy, precision, sensitivity, and specificity were higher than 0.8 (p<0.05). DVH relative percentage difference between the error-free and error datasets was examined to investigate clinical relations.Results: Statistically common significant indices were found, GLCM_Energy in Class-I and Class-III and GLRLM_LRHGE in Class-II. The final model was developed using indices that satisfied the statistical criteria. The number of finalized univariate predictive models was five in Class-I and Class-II and four in Class-III. Seven multivariate predictive models were finalized. The DVH relative percentage difference between the error-free and error dataset almost linearly increased as systematic error increased. In the case of random errors, the tendency of the DVH relative percentage difference was dependent on the structure’s location.Conclusion: Our study highlights three novel vital results. First, the common significant dosiomics indices (GLCM Energy and GLRLM_LRHGE) can characterize the MLC position error. Second, the finalized logistic regression model for MLC position error prediction showed excellent performance with AUC > 0.9. Third, the results of DVH were related to dosiomics analysis in that it reflects the characteristics of the MLC position error, and it was shown that dosiomics analysis could provide important information on localized dose distribution differences in addition to DVH information.
The uncertainties of four-dimensional computed tomography (4DCT), also called as residual motion artefacts (RMA), induced from irregular respiratory patterns can degrade the quality of overall radiotherapy. This study aims to quantify and reduce those uncertainties. A comparative study on quantitative indicators for RMA was performed, and based on this, we proposed a new 4DCT sorting method that is applicable without disrupting the current clinical workflow. In addition to the default phase sorting strategy, both additional amplitude information from external surrogates and the quantitative metric for RMA, investigated in this study, were introduced. The comparison of quantitative indicators and the performance of the proposed sorting method were evaluated via 10 cases of breath-hold (BH) CT and 30 cases of 4DCT. It was confirmed that N-RMSD (normalised root-mean-square-deviation) was best matched to the visual standards of our institute’s regime, manual sorting method, and could accurately represent RMA. The performance of the proposed method to reduce 4DCT uncertainties was improved by about 18.8% in the averaged value of N-RMSD compared to the default phase sorting method. To the best of our knowledge, this is the first study that evaluates RMA indicators using both BHCT and 4DCT with visual-criteria-based manual sorting and proposes an improved 4DCT sorting strategy based on them.
Background This study investigated the effect of accumulated doses on radio-photoluminescence glass dosimeters (RPLGDs) from measurements involving mega-voltage photons. Methods Forty-five commercially available RPLGDs were irradiated to estimate their dose responses. Photon beams of 6, 10, and 15 MV were irradiated onto the RPLGDs inside a phantom, which were divided into five groups with different doses and energies. Groups 1 and 2 were irradiated at 1, 5, 10, 50, and 100 Gy in a sequential manner; Group 3 was irradiated 10 times with a dose of 10 Gy; and Groups 4 and 5 followed the same method as that of Group 3, but with doses of 50 Gy and 100 Gy, respectively. Each device was subjected to a measurement reading procedure each time irradiation. Results For the annealed Group 1, RPLGD exhibited a linearity response with variance within 5%. For the non-annealed Group 2, readings demonstrated hyperlinearity at 6 MV and 10 MV, and linearity at 15 MV. Following the 100 Gy irradiation, the readings for Group 2 were 118.7 ± 1.9%, 112.2 ± 2.7%, and 101.5 ± 2.3% at 6, 10, and 15 MV, respectively. For Groups 3, 4, and 5, the responsiveness of the RPLGDs gradually decreased as the number of repeated irradiations increased. The percentage readings for the 10th beam irradiation with respect to the readings for the primary beam irradiation were 84.6 ± 1.9%, 87.5 ± 2.4%, and 93.0 ± 3.0% at 6 MV, 10 MV, and 15 MV, respectively. Conclusions The non-annealed RPLGD response to dose was hyperlinear for the 6 MV and 10 MV photon beams but not for the 15 MV photon beam. Additionally, the annealed RPLGD exhibited a fading phenomenon when the measurement was repeated several times and demonstrated a relatively large fading effect at low energies than at high energies.
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