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Grant
Agency: European Commission | Branch: FP7 | Program: BSG-SME | Phase: SME-1 | Award Amount: 1.43M | Year: 2008

The project develops an innovative x-ray source based on the emerging technology of field emitting carbon nanotubes (CNT). This kind of source has several advantages with respect to traditional sources: higher intrinsic brilliance; possibility to work in pulsed and continuous mode; higher peak power; minor power consumption; modularity of beam size; good stability and longer life time. These sources are also more compact and robust, therefore suitable to be portable. The R&D activity is based on four major blocks: i) development of the cathode made of a well aligned CNT array, capable of delivering high current electron density in continuous and pulsed mode; ii) fabrication of a CNT-based electron gun which combines the CNT cathode with electron focusing optics; iii) integration of the e-gun in x-ray sources, and fabrication of an x-ray microfocusing source with characteristics of high brilliance, continuous and pulsed operation modes, easy control of beam size and power; iv) integration of the microfocusing source in two x-ray systems devoted to specific applications: a tomographic system for biomedical applications and an advanced system for material metrology applications. The implementation of phase contrast imaging methodology with this innovative source will be studied. The project will strongly enhance the competitiveness of the SMEs involved in the project. The potential exploitation goes far beyond the examples addressed in the project: X-ray sources are routinely used in medical radiography, in security, in industrial quality control, in advanced research, in environmental issues and in cultural heritage. The availability of innovative sources with improved features with respect to the standard ones will have a great impact not only on Europe competitiveness in this field but also on societal aspects such as health, security, product quality, sustainability.


Burghardt A.J.,University of California at San Francisco | Buie H.R.,University of Calgary | Laib A.,Scanco Medical AG | Majumdar S.,University of California at San Francisco | Boyd S.K.,University of Calgary
Bone | Year: 2010

Quantitative cortical microarchitectural end points are important for understanding structure-function relations in the context of fracture risk and therapeutic efficacy. This technique study details new image-processing methods to automatically segment and directly quantify cortical density, geometry, and microarchitecture from HR-pQCT images of the distal radius and tibia.An automated segmentation technique was developed to identify the periosteal and endosteal margins of the distal radius and tibia and detect intracortical pore space morphologically consistent with Haversian canals. The reproducibility of direct quantitative cortical bone indices based on this method was assessed in a pooled data set of 56 subjects with two repeat acquisitions for each site. The in vivo precision error was characterized using root mean square coefficient of variation (RMSCV%) from which the least significant change (LSC) was calculated. Bland-Altman plots were used to characterize bias in the precision estimates.The reproducibility of cortical density and cross-sectional area measures was high (RMSCV <1% and <1.5%, respectively) with good agreement between young and elder medians. The LSC for cortical porosity (Ct.Po) was somewhat smaller in the radius (0.58%) compared with the distal tibia (0.84%) and significantly different between young and elder medians in the distal tibia (LSC: 0.75% vs. 0.92%, p<0.001). The LSC for pore diameter and distribution (Po.Dm and Po.Dm.SD) ranged between 15 and 23μm. Bland-Altman analysis revealed moderate bias for integral measures of area and volume but not for density or microarchitecture.This study indicates that HR-pQCT measures of cortical bone density and architecture can be measured in vivo with high reproducibility and limited bias across a biologically relevant range of values. The results of this study provide informative data for the design of future clinical studies of bone quality. © 2010 Elsevier Inc.


Blom H.,KTH Royal Institute of Technology | Hassler K.,KTH Royal Institute of Technology | Hassler K.,SCANCO Medical AG | Chmyrov A.,KTH Royal Institute of Technology | Widengren J.,KTH Royal Institute of Technology
International Journal of Molecular Sciences | Year: 2010

Electrostatic interactions between dielectric surfaces and different fluorophores used in ultrasensitive fluorescence microscopy are investigated using objective-based Total Internal Reflection Fluorescence Correlation Spectroscopy (TIR-FCS). The interfacial dynamics of cationic rhodamine 123 and rhodamine 6G, anionic/dianionic fluorescein, zwitterionic rhodamine 110 and neutral ATTO 488 are monitored at various ionic strengths at physiological pH. As analyzed by means of the amplitude and time-evolution of the autocorrelation function, the fluorescent molecules experience electrostatic attraction or repulsion at the glass surface depending on their charges. Influences of the electrostatic interactions are also monitored through the triplet-state population and triplet relaxation time, including the amount of detected fluorescence or the count-rate-per-molecule parameter. These TIR-FCS results provide an increased understanding of how fluorophores are influenced by the microenvironment of a glass surface, and show a promising approach for characterizing electrostatic interactions at interfaces. © 2010 by the authors; licensee Molecular Diversity Preservation International.


Grant
Agency: European Commission | Branch: FP7 | Program: CP-FP | Phase: HEALTH.2012.2.4.5-1 | Award Amount: 4.74M | Year: 2012

Cochlear implantation is a surgical procedure that aims to overcome hearing loss by direct electrical stimulation of the spiral ganglion cells in the cochlea of the inner ear. The surgical scenario of implantation surgery is very complex. It requires high clinical expertise in order to 1) efficiently access the surgical site, the cochlea, localize nearby critical structures (e.g. facial nerve) and 2) optimize the position of the implantable device (electrode array) inside the cochlea. Furthermore, there is a vast anatomical variability amongst patients. This makes individual optimal fitting an extremely difficult task and strongly influences the success of the surgery and subsequently hearing restoration. We hypothesize that a comprehensive understanding of the shape variability of the middle and inner ear among patients will enable the design improvement of hearing implants, and will be of assistance during surgical planning. Consequently, the aim of this project is: 1) to develop a novel high-resolution high-energy microCT device to obtain detailed images of the middle and inner ear, even in the presence of metallic implants, 2) to build a model of the shape variability of the middle and inner ear from high-resolution images, also incorporating functional information, 3) to build a computer-assisted patient-specific preoperative planning system, and 4) to improve the design of cochlear implant (CI) electrode arrays and associated insertion tools using a population-based optimization framework. All objectives revolve around the criteria of minimizing invasiveness, insertion-induced trauma and enhanced functional outcome through patient-specific frequency mapping. The consortium is composed of two research-intensive SMEs, one university hospital, two universities, and a large European enterprise. This project will lead to important strategic benefits for all partners, and very especially for the SMEs.


Sengle G.,University of Cologne | Tufa S.F.,Shriners Hospital for Children | Sakai L.Y.,Shriners Hospital for Children | Sakai L.Y.,Oregon Health And Science University | And 3 more authors.
Journal of Histochemistry and Cytochemistry | Year: 2013

We present a method in which a precise region of interest within an intact organism is spatially mapped in three dimensions by non-invasive micro-computed X-ray tomography (micro-CT), then further evaluated by light microscopy (LM) and transmission electron microscopy (TEM). Tissues are prepared as if for TEM including osmium fixation, which imparts soft tissue contrast in the micro-CT due to its strong X-ray attenuation. This method may therefore be applied to embedded, archived TEM samples. Upon selection of a two-dimensional (2-D) projection from a region of interest (ROI) within the three-dimensional volume, the epoxyembedded sample is oriented for microtomy so that the sectioning plane is aligned with the micro-CT projection. Registration is verified by overlaying LM images with 2-D micro-CT projections. Structures that are poorly resolved in the micro-CT may be evaluated at TEM resolution by observing the next serial ultrathin section, thereby accessing the same ROI by all three imaging techniques. We compare white adipose tissue within the forelimbs of mice harboring a lipid-altering mutation with their littermate controls. We demonstrate that individual osmium-stained lipid droplets as small as 15 μm and separated by as little as 35 μm may be discerned as separate entities in the micro-CT, validating this to be a high-resolution, non-destructive technique for evaluation of fat content. © The Author(s) 2013.


Baritaux J.-C.,Ecole Polytechnique Federale de Lausanne | Hassler K.,SCANCO Medical AG | Bucher M.,SCANCO Medical AG | Sanyal S.,Ecole Polytechnique Federale de Lausanne | Unser M.,Ecole Polytechnique Federale de Lausanne
IEEE Transactions on Medical Imaging | Year: 2011

In this paper we propose a method based on (2, 1)-mixed-norm penalization for incorporating a structural prior in FDOT image reconstruction. The effect of (2, 1)-mixed-norm penalization is twofold: first, a sparsifying effect which isolates few anatomical regions where the fluorescent probe has accumulated, and second, a regularization effect inside the selected anatomical regions. After formulating the reconstruction in a variational framework, we analyze the resulting optimization problem and derive a practical numerical method tailored to (2, 1)-mixed-norm regularization. The proposed method includes as particular cases other sparsity promoting regularization methods such as l 1-norm penalization and total variation penalization. Results on synthetic and experimental data are presented. © 2010 IEEE.


Rizzoli R.,University of Geneva | Chapurlat R.D.,University of Lyon | Laroche J.-M.,Toulouse University Hospital Center | Krieg M.A.,CHUV | And 6 more authors.
Osteoporosis International | Year: 2012

Summary Strontium ranelate appears to influence more than alendronate distal tibia bone microstructure as assessed by high-resolution peripheral quantitative computed tomography (HR-pQCT), and biomechanically relevant parameters as assessed by micro-finite element analysis (μFEA), over 2 years, in postmenopausal osteoporotic women. Introduction Bone microstructure changes are a target in osteoporosis treatment to increase bone strength and reduce fracture risk. Methods Using HR-pQCT, we investigated the effects on distal tibia and radius microstructure of strontium ranelate (SrRan; 2 g/day) or alendronate (70 mg/week) for 2 years in postmenopausal osteoporotic women. This exploratory randomized, double-blind trial evaluated HR-pQCT and FEA parameters, areal bone mineral density (BMD), and bone turnover markers. Results In the intention-to-treat population (n=83, age: 64± 8 years; lumbar T-score: -2.8±0.8 [DXA]), distal tibia Cortical Thickness (CTh) and Density (DCort), and cancellous BV/TV increased by 6.3%, 1.4%, and 2.5%, respectively (all P<0.005), with SrRan, but not with alendronate (0.9%, 0.4%, and 0.8%, NS) (P<0.05 for all above betweengroup differences). Difference for CTh evaluated with a distance transformation method was close to significance (P=0.06). The estimated failure load increased with SrRan (+2.1%, P<0.005), not with alendronate (-0.6%, NS) (between-group difference, P<0.01). Cortical stress was lower with SrRan (P<0.05); both treatments decreased trabecular stress. At distal radius, there was no betweengroup difference other than DCort (P<0.05). Bone turnover markers decreased with alendronate; bALP increased (+21%) and serum-CTX-I decreased (-1%) after 2 years of SrRan (between-group difference at each time point for both markers, P<0.0001). Both treatments were well tolerated. Conclusions Within the constraints of HR-pQCT method, and while a possible artefactual contribution of strontium cannot be quantified, SrRan appeared to influence distal tibia bone microstructure and FEA-determined biomechanical parameters more than alendronate. However, the magnitude of the differences is unclear and requires confirmation with another method. © International Osteoporosis Foundation and National Osteoporosis Foundation 2011.


Baritaux J.-C.,Ecole Polytechnique Federale de Lausanne | Hassler K.,SCANCO Medical AG | Unser M.,Ecole Polytechnique Federale de Lausanne
IEEE Transactions on Medical Imaging | Year: 2010

Reconstruction algorithms for fluorescence tomography have to address two crucial issues: 1) the ill-posedness of the reconstruction problem, 2) the large scale of numerical problems arising from imaging of 3-D samples. Our contribution is the design and implementation of a reconstruction algorithm that incorporates general Lp regularization $(p\geqslant 1)$. The originality of this work lies in the application of general Lp constraints to fluorescence tomography, combined with an efficient matrix-free strategy that enables the algorithm to deal with large reconstruction problems at reduced memory and computational costs. In the experimental part, we specialize the application of the algorithm to the case of sparsity promoting constraints $(L1). We validate the adequacy of L1 regularization for the investigation of phenomena that are well described by a sparse model, using data acquired during phantom experiments. © 2006 IEEE.


PubMed | Vienna University of Technology, SCANCO Medical AG, Bern University of Applied Sciences, TU Eindhoven and 2 more.
Type: | Journal: Bone | Year: 2017

Fractures of the distal section of the radius (Colles fractures) occur earlier in life than other osteoporotic fractures. Therefore, they can be interpreted as a warning signal for later, more deleterious fractures of vertebral bodies or the femoral neck. In the past decade, the advent of HR-pQCT allowed a detailed architectural analysis of the distal radius and an automated but time-consuming estimation of its strength with linear micro-finite element (FE) analysis. Recently, a second generation of HR-pQCT scanner (XtremeCT II, SCANCO Medical, Switzerland) with a resolution beyond 61 m became available for even more refined biomechanical investigations in vivo. This raises the question how biomechanical outcome variables compare between the original (LR) and the new (HR) scanner resolution. Accordingly, the aim of this work was to validate experimentally a patient-specific homogenized finite element (hFE) analysis of the distal section of the human radius for the fast prediction of Colles fracture load based on the last generation HR-pQCT. Fourteen pairs of fresh frozen forearms (mean age = 77.59) were scanned intact using the high (61 m) and the low (82 m) resolution protocols that correspond to the new and original HR-pQCT systems. From each forearm, the 20mm most distal section of the radius were dissected out, scanned with CT at 16.4 m and tested experimentally under compression up to failure for assessment of stiffness and ultimate load. Linear and nonlinear hFE models together with linear micro finite element (FE) models were then generated based on the CT and HR-pQCT reconstructions to predict the aforementioned mechanical properties of 24 sections. Precision errors of the short term reproducibility of the FE analyses were measured based on the repeated scans of 12 sections. The calculated failure loads correlated strongly with those measured in the experiments: accounting for donor as a random factor, the nonlinear hFE provided a marginal coefficient of determination (R


PubMed | Universitatsklinikum of Dusseldorf and Scanco Medical AG
Type: | Journal: Clinical oral implants research | Year: 2016

To (i) assess the impact of insertion depth and abutment microstructure on the three-dimensional crestal bone-level changes at endosseous titanium implant using CT and computerized image processing and (ii) to correlate the findings with previously reported histology.Titanium implants (conical abutment connection) were inserted in each hemimandible of n=6 foxhounds with the implant shoulder (IS) located either in epicrestal (0mm), supracrestal (+1mm) or subcrestal (-1mm) positions and randomly (split-mouth design) connected with machined or partially micro-grooved healing abutments. At 20weeks, the tissue biopsies were processed for CT and histological (HI) analyses. The volumetric dehiscence profile around the implants was computed as distance between the implant shoulder (IS) and the most coronal bone-to-implant contact (CBI) using MATLAB. The respective buccal and oral values were averaged, and agreement with the respective IS-CBI scores from HI was assessed using Bland-Altman plots.A median net bone gain was observed for supracrestal insertion depths at both abutment types, but lower bounds of the 75% quartile experienced net bone losses. Epicrestal and subcrestal insertion depths were linked to slight bone losses, and the buccal and oral dehiscences were smaller compared to supracrestal positioning. Bland-Altman plots yielded a moderate agreement of IS-CBI values measured with CT and HI.The novel image processing method allowed reliable evaluations and pointed to a direct impact of insertion depths on crestal bone-level changes. Additionally, it demonstrated that HI morphometry crucially depends on the chosen cutting position.

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