Backscattered Electron Imaging Using Single Crystal Scintillator Detectors

The image obtained by the detection of backscattered electrons (BSE) becomes an indispensable complement to the correct interpretation and more precise reconstruction of the surface of the specimen and its material composition. The BSE are carriers of information which is dependent on their angular and energy distribution. The choice of a certain type of BSE and their efficient detection make it possible to record the desired information with a different grade of quality. The knowledge of the angular and energy distribution of BSE is necessary for the adjustment of the correct position of the BSE detector with regard to the specimen and for its optimum geometrical configuration. The directional detection of a limited number of the BSE selected according to their angle and energy makes high demands on the efficiency of the detector. The paper presents BSE detectors based on single crystal aluminium oxides of YAG and YAP. Their spectral characteristics, time characteristics, detection quantum efficiency, electron resistance and mechanical, temperature and vacuum properties satisfy all demands of electron microscopy. The number of differently modified BSE detectors with single crystal scintillators allow application of various detection techniques, recording of different contrast mechanisms, combination of different detection modes (simultaneous detection), achievement of a high resolution of the BSE image. The paper reviews some 180 published papers by other authors. Their findings and the present author\u27s experimental results have formed the basis for backscattered electron imaging using single crystal scintillator detectors

The global retinoblastoma outcome study : a prospective, cluster-based analysis of 4064 patients from 149 countries

DATA SHARING : The study data will become available online once all analyses are complete.BACKGROUND : Retinoblastoma is the most common intraocular cancer worldwide. There is some evidence to suggest that major differences exist in treatment outcomes for children with retinoblastoma from different regions, but these differences have not been assessed on a global scale. We aimed to report 3-year outcomes for children with retinoblastoma globally and to investigate factors associated with survival. METHODS : We did a prospective cluster-based analysis of treatment-naive patients with retinoblastoma who were diagnosed between Jan 1, 2017, and Dec 31, 2017, then treated and followed up for 3 years. Patients were recruited from 260 specialised treatment centres worldwide. Data were obtained from participating centres on primary and additional treatments, duration of follow-up, metastasis, eye globe salvage, and survival outcome. We analysed time to death and time to enucleation with Cox regression models. FINDINGS : The cohort included 4064 children from 149 countries. The median age at diagnosis was 23·2 months (IQR 11·0–36·5). Extraocular tumour spread (cT4 of the cTNMH classification) at diagnosis was reported in five (0·8%) of 636 children from high-income countries, 55 (5·4%) of 1027 children from upper-middle-income countries, 342 (19·7%) of 1738 children from lower-middle-income countries, and 196 (42·9%) of 457 children from low-income countries. Enucleation surgery was available for all children and intravenous chemotherapy was available for 4014 (98·8%) of 4064 children. The 3-year survival rate was 99·5% (95% CI 98·8–100·0) for children from high-income countries, 91·2% (89·5–93·0) for children from upper-middle-income countries, 80·3% (78·3–82·3) for children from lower-middle-income countries, and 57·3% (52·1-63·0) for children from low-income countries. On analysis, independent factors for worse survival were residence in low-income countries compared to high-income countries (hazard ratio 16·67; 95% CI 4·76–50·00), cT4 advanced tumour compared to cT1 (8·98; 4·44–18·18), and older age at diagnosis in children up to 3 years (1·38 per year; 1·23–1·56). For children aged 3–7 years, the mortality risk decreased slightly (p=0·0104 for the change in slope). INTERPRETATION : This study, estimated to include approximately half of all new retinoblastoma cases worldwide in 2017, shows profound inequity in survival of children depending on the national income level of their country of residence. In high-income countries, death from retinoblastoma is rare, whereas in low-income countries estimated 3-year survival is just over 50%. Although essential treatments are available in nearly all countries, early diagnosis and treatment in low-income countries are key to improving survival outcomes.The Queen Elizabeth Diamond Jubilee Trust and the Wellcome Trust.https://www.thelancet.com/journals/langlo/homeam2023Paediatrics and Child Healt

Attachment of Composites to Hard Dental Tissues and Morphological Comparison of Effects of Two Adhesive Techniques

Introduction: The authors review the present state of the problems in connecting composite materials to hard dental tissues. Objective: The aim of the work was to examine and compare the appearance of enamel after adhesive adjustment (adaptation) by a total etching technique after treatment with an acid primer of the self-etching adhesive. Material and Methods: The experiment was made with 30 premolars extracted for orthodontic reasons. The extracted teeth were divided into groups, five premolars each. The etching gel of orthophosphoric acid was used for enamel without grinding as well as for enamel freed of the most superficial layer by grinding. After rinsing and drying the enamel prepared in this way was observed by electron microscope. In order to examine the adhesive preparation of dentine, grinding for denuding the dentin and formation of smear layer was made in 10 samples. The dentin prepared in this way was treated in five samples with orthophosphoric acid and by an acid primer in five other samples. The results were examined by electron microscope. Results: It has become obvious that the enamel treated with orthophosphoric acid displayed a jaggier surface of better quality for mechanical adhesion than the enamel treated with a self-etching primer. In the morphology of dentine surface there was no difference between the two ways of treatment. Conclusion: The self-etching adhesives are substantiated in cases, where more extensive atreas of dentine are available. They represent a lower risk of tightness in joining the filling