200 research outputs found

    Learning about tooth removal with robot technology

    Get PDF
    Deze PhD-thesis richt zich op een fundamenteel onderzoek van de extractieleer en maakt daarbij gebruik van robottechnologie. Het onderzoek omvat zes inhoudelijke hoofdstukken, waarin verschillende aspecten van dit onderwerp worden behandeld. Het tweede hoofdstuk analyseert de literatuur over robottechnologie in de tandheelkunde en wijst op de matige kwaliteit van beschikbare literatuur, zeker als het op klinische toepassingen aankomt. Hoofdstuk 3 biedt een overzicht van robotsystemen in alle deelgebieden van de tandheelkunde sinds 1985. Hoofdstuk 4 introduceert een meetopstelling om krachten en bewegingen bij tandextracties nauwkeurig vast te leggen, terwijl hoofdstuk 5 de resultaten van een serie experimenten voor wat betreft krachten en momenten weergeeft. Hoofdstuk 6 beschrijft het bewegingsbereik en de snelheden tijdens tandheelkundige extracties, zoals gemeten met een robotarm. Hoofdstuk 7 beschrijft de ontwikkeling en eigenschappen van een classificatiemodel voor extracties op basis van kracht- en bewegingsgegevens. De conclusie benadrukt de toenemende interesse in robotinitiatieven in de tandheelkunde, de behoefte aan wetenschappelijke validatie van de toegevoegde waarde daarvan en het potentieel van robottechnologie om ons fundamentele begrip van de extractieleer te vergroten. De studies benadrukken het belang van gegevensverzameling, analyse en samenwerking tussen verschillende disciplines om ons fundamentele begrip van extracties te verbeteren, met een focus op tandheelkundig onderwijs en uiteindelijk de patiëntenzorg

    Mesh-to-raster based non-rigid registration of multi-modal images

    Full text link
    Region of interest (ROI) alignment in medical images plays a crucial role in diagnostics, procedure planning, treatment, and follow-up. Frequently, a model is represented as triangulated mesh while the patient data is provided from CAT scanners as pixel or voxel data. Previously, we presented a 2D method for curve-to-pixel registration. This paper contributes (i) a general mesh-to-raster (M2R) framework to register ROIs in multi-modal images; (ii) a 3D surface-to-voxel application, and (iii) a comprehensive quantitative evaluation in 2D using ground truth provided by the simultaneous truth and performance level estimation (STAPLE) method. The registration is formulated as a minimization problem where the objective consists of a data term, which involves the signed distance function of the ROI from the reference image, and a higher order elastic regularizer for the deformation. The evaluation is based on quantitative light-induced fluoroscopy (QLF) and digital photography (DP) of decalcified teeth. STAPLE is computed on 150 image pairs from 32 subjects, each showing one corresponding tooth in both modalities. The ROI in each image is manually marked by three experts (900 curves in total). In the QLF-DP setting, our approach significantly outperforms the mutual information-based registration algorithm implemented with the Insight Segmentation and Registration Toolkit (ITK) and Elastix

    CYTOKINES IN GINGIVAL CREVICULAR FLUID AND ROOT RESORPTION: A MICROCOMPUTED TOMOGRAPHY STUDY

    Get PDF

    Radiation dose optimization in interventional radiology and cardiology using diagnostic reference levels

    Get PDF
    The International Commission of Radiological Protection (ICRP) advises that in principle Diagnostic Reference Levels (DRL) could be used in fluoroscopically guided interventional procedures to avoid unnecessary stochastic radiation risk. The increase in complexity of interventional procedures, combined with a lack of specialist training on radiation techniques, poses a significant risk to patients. These risks have not gone unnoticed by government authorities worldwide and in 2015 the South African Department of Health: Directorate Radiation Control issued requirements to license holders of interventional fluoroscopy units, requiring that a medical physicist optimize their radiation usage using DRLs. The Dose Area Product (DAP) quantity measured for each patient represents a dosimetry index, the value of which for the purpose of improvement should be optimized against the DRL. In this dissertation, I aim to establish if DRLs in the South African private healthcare interventional theatres are high compared to international levels and whether DRLs will optimize the doses used

    Catalog 1983-84

    Get PDF
    https://openspace.dmacc.edu/catalogs/1011/thumbnail.jp

    Catalog 1995-96

    Get PDF
    https://openspace.dmacc.edu/catalogs/1028/thumbnail.jp

    Interlandmark measurements from lodox statscan images with application to femoral neck anteversion assessment

    Get PDF
    Includes abstract.Includes bibliographical references.Clinicians often take measurements between anatomical landmarks on X-ray radiographs for diagnosis and treatment planning, for example in orthopaedics and orthodontics. X-ray images, however, overlap three-dimensional internal structures onto a two-dimensional plane during image formation. Depth information is therefore lost and measurements do not truly reflect spatial relationships. The main aim of this study was to develop an inter-landmark measurement tool for the Lodox Statscan digital radiography system. X-ray stereophotogrammetry was applied to Statscan images to enable three-dimensional point localization for inter-landmark measurement using two-dimensional radiographs. This technique requires images of the anatomical region of interest to be acquired from different perspectives as well as a suitable calibration tool to map image coordinates to real world coordinates. The Statscan is suited to the technique because it is capable of axial rotations for multiview imaging. Three-dimensional coordinate reconstruction and inter-landmark measurements were taken using a planar object and a dry pelvis specimen in order to assess the intra-observer measurement accuracy, reliability and precision. The system yielded average (X, Y, Z) coordinate reconstruction accuracy of (0.08 0.12 0.34) mm and resultant coordinate reconstruction accuracy within 0.4mm (range 0.3mm – 0.6mm). Inter-landmark measurements within 2mm for lengths and 1.80 for angles were obtained, with average accuracies of 0.4mm (range 0.0mm – 2.0 mm) and 0.30 (range 0.0 – 1.8)0 respectively. The results also showed excellent overall precision of (0.5mm, 0.10) and were highly reliable when all landmarks were completely visible in both images. Femoral neck anteversion measurement on Statscan images was also explored using 30 dry right adult femurs. This was done in order to assess the feasibility of the algorithm for a clinical application. For this investigation, four methods were tested to determine the optimal landmarks for measurement and the measurement process involved calculation of virtual landmarks. The method that yielded the best results produced all measurements within 10 of reference values and the measurements were highly reliable with very good precision within 0.10. The average accuracy was within 0.40 (range 0.10 –0.80).In conclusion, X-ray stereophotogrammetry enables accurate, reliable and precise inter-landmark measurements for the Lodox Statscan X-ray imaging system. The machine may therefore be used as an inter-landmark measurement tool for routine clinical applications
    • …
    corecore