Samenvatting: In het kader van een afstudeerproject zijn data van 33 kinderen verzameld die een X-abdomen onderzoek ondergingen in het Wilhelmina Kinderziekenhuis. Uit deze data zijn curves afgeleid van Dosis Oppervlakte Product (DOP) ten opzichte van het lichaamsgewicht om te dienen als Diagnostisch ReferentieNiveau (DRN). De spreiding in de data leidt echter tot onzekerheid over de beste DRN-curve. Die curve is bovendien slechts gebaseerd op de data van één ziekenhuis en is daarmee hooguit bruikbaar als lokaal DRN. Door deze studie te herhalen in andere ziekenhuizen en meer data te verzamelen zou een nationale DRN-curve afgeleid kunnen worden. Zo’n curve zou de toetsing van doses aan DRN’s voor kinderen vergemakkelijken.
DOCUMENT
Op verzoek van Jelle Scheurleer: Purpose: To investigate the accuracy of dose calculation on cone beam CT (CBCT) data sets after HU-RED calibration and validation in phantom studies and clinical patients. Material and methods: Calibration of HU-RED curves for kV-CBCT were generated for three clinical protocols (H&N, thorax and pelvis) by using a Gammex RMI phantom with human tissue equivalent inserts and additional perspex blocks to account for patient scatter. Two calibration curves per clinical protocol were defined, one for the Varian Truebeam 2.0 and another for the OBI systems (Varian, Palo Ato). Differences in HU values with respect to the CT-calibration curve were evaluated for all the inserts. Four radiotherapy plans (breast, prostate, H&N and lung) were produced on an anthropomorphic phantom (Alderson) to evaluate dose differences on the kV-CBCT with the new calibration curves with respect to the CT based dose calculation. Dose differences were evaluated according to the D2%, D98% and Dmean metrics extracted from the DVHs of the plans and - evaluation (2%, 1mm) on the three planes at the isocenter for all plans. Clinical evaluation was performed on 5 patients and dose differences were evaluated as in the phantom study.
DOCUMENT
Development of novel testing strategies to detect adverse human health effects is of interest to replace in vivo-based drug and chemical safety testing. The aim of the present study was to investigate whether physiologically based kinetic (PBK) modeling-facilitated conversion of in vitro toxicity data is an adequate approach to predict in vivo cardiotoxicity in humans. To enable evaluation of predictions made, methadone was selected as the model compound, being a compound for which data on both kinetics and cardiotoxicity in humans are available. A PBK model for methadone in humans was developed and evaluated against available kinetic data presenting an adequate match. Use of the developed PBK model to convert concentration–response curves for the effect of methadone on human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) in the so-called multi electrode array (MEA) assay resulted in predictions for in vivo dose–response curves for methadone-induced cardiotoxicity that matched the available in vivo data. The results also revealed differences in protein plasma binding of methadone to be a potential factor underlying variation between individuals with respect to sensitivity towards the cardiotoxic effects of methadone. The present study provides a proof-of-principle of using PBK modeling-based reverse dosimetry of in vitro data for the prediction of cardiotoxicity in humans, providing a novel testing strategy in cardiac safety studies.
MULTIFILE
Size measurement plays an essential role for micro-/nanoparticle characterization and property evaluation. Due to high costs, complex operation or resolution limit, conventional characterization techniques cannot satisfy the growing demand of routine size measurements in various industry sectors and research departments, e.g., pharmaceuticals, nanomaterials and food industry etc. Together with start-up SeeNano and other partners, we will develop a portable compact device to measure particle size based on particle-impact electrochemical sensing technology. The main task in this project is to extend the measurement range for particles with diameters ranging from 20 nm to 20 um and to validate this technology with realistic samples from various application areas. In this project a new electrode chip will be designed and fabricated. It will result in a workable prototype including new UMEs (ultra-micro electrode), showing that particle sizing can be achieved on a compact portable device with full measuring range. Following experimental testing with calibrated particles, a reliable calibration model will be built up for full range measurement. In a further step, samples from partners or potential customers will be tested on the device to evaluate the application feasibility. The results will be validated by high-resolution and mainstream sizing techniques such as scanning electron microscopy (SEM), dynamic light scattering (DLS) and Coulter counter.
Vanuit het werkveld is er een steeds grotere behoefte aan duurzame bouwstenen om materialen te ontwikkelen. Op gebied van materiaalontwikkeling, biedt additive manufacturing (AM) de mogelijkheid om een veelzijdig aanbod aan op maat gemaakte materialen te produceren. Een belangrijke klasse materialen gebruikt in AM zijn thermohardende fotopolymeren. Hoewel thermohardende fotopolymeren duurzaam zijn omdat geen milieuvervuilende, vluchtige organische solventen nodig zijn in de formuleringen, zijn de op de markt beschikbare thermohardende fotopolymeerformulaties nog niet duurzaam genoeg. De grondstoffen zijn meestal nog van fossiele oorsprong en eens uitgehard zijn de 3D geprinte objecten niet meer recycleerbaar of herverwerkbaar tot andere objecten. In dit project zullen NHL Stenden, Universiteit Maastricht en Liqcreate werken aan het ontwikkelen van biogebaseerde fotopolymeerharsen op basis van bouwstenen afgeleid van lignine, vetzuur en kampfer. Bovendien zullen de bouwstenen reversibele bindigen bevatten die toelaten om anders niet recycleerbare uitgeharde producten bij verhoogde temperatuur toch te kunnen verwerken als een thermoplast, wat de weg opent naar recyclage. Op basis van deze bouwstenen zullen fotopolymeerformulaties worden gemaakt en uitgehard, waarna de mechanische eigenschappen in kaart worden gebracht. De beste fotopolymeer formulaties zullen worden gebruikt voor het 3D printen van objecten, waarvan de recycleerbaarheid bestudeerd zal worden.
The project is for protecting valuable museum contents against seismic actions. Assessment and protection methods and equipment will be developed and tested. - Assessment methods for seismic safety of museum contents- Protective devices for the musem contentsA museum virtual exhibition room (MVER) will be created, it will contain exhibits such as sculptures and artefacts of different size and geometry, while the proposed experimental work will first examine the seismic behaviour of the test specimens without any protection system. The tests will be repeated using different protective configurations, emphasising on low-mass base isolation systems. Two new and highly efficient base isolation systems will be extensively tested for the first time. The first isolator is a pendulum-based system, while the second utilises shape-memory-alloy wires.The project will also develop and calibrate novel numerical models for single- and two- block rocking systems, while experimental and numerical results will be combined in order to develop quick overturning assessment criteria for the artefacts considered.The final task of the project will combine the shaking table experimental outcomes with numerical results using calibrated numerical models in order to develop fragility curves for museum artefacts.
