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  • Conference Proceeding  (38)
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  • Conference Proceeding  (38)
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  • 1
    Language: English
    In: 11 February 2010, Vol.7564, pp.75642Z-75642Z-5
    Description: Over the last decade fluorescent reporter technologies (both fluorescent probes and proteins) have become a very powerful imaging tool in everyday biomedical research. Multispectral optoacoustic tomography (MSOT) is an emerging imaging technology that can resolve fluorophore concentration in small animals situated in deep tissue by multispectral acquisition and processing of optoacoustic signals. In this work, we study the optimum operating conditions of MSOT in imaging fluorescence activity in small animals. The performance of various fluorochromes / fluorescent proteins is examined and it is shown that the new infrared fluorescent protein is an order of magnitude brighter than the red ones. Finally, wavelength reduction after principle component analysis shows, that accurate unmixing and 3D reconstruction of the distribution of fluorochromes is possible only with 2 or 3 wavelengths.
    Keywords: Engineering
    ISBN: 9780819479600
    ISBN: 0819479608
    ISSN: 0277786X
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  • 2
    Language: English
    In: Proceedings of SPIE, 20 August 2004, Vol.5474(1), pp.215-223
    Description: We present a simple and novel theoretical approach for modeling the intensity distribution from an arbitrarily shaped turbid volume in a non-contact geometry by considering diffuse light propagation in free-space. Optical tomography of turbid media has so far been limited by systems that require fixed geometries or fiber measurements. This novel theory is validated with experiments for a diffusive volume of known geometry in a non-contact situation, both with and without the presence of an embedded absorber. We also present a system that records non-contact optical measurements from diffuse media of arbitrary shapes and retrieves the three-dimensional surface information of the diffuse medium. This approach offers significant experimental simplicity and yields high-information content datasets. The performance of this novel tomographic approach is demonstrated with experimental reconstructions of phantoms. Finally, the implications of this new formulation in the context of optical tomography in turbid media are discussed.
    Keywords: Engineering
    ISBN: 9780819453976
    ISSN: 0277-786X
    ISSN: 16057422
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  • 3
    Language: English
    In: Proceedings of SPIE, 26 February 2009, Vol.7258(1), pp.725812-725818
    Description: We describe an improved optoacoustic tomography method, that utilizes a diffusion-based photon propagation model in order to obtain quantified reconstruction of targets embedded deep in heterogeneous scattering and absorbing tissue. For the correction we utilize an iterative finite-element solution of the light diffusion equation to build a photon propagation model. We demonstrate image improvements achieved by this method by using tissue-mimicking phantom measurements. The particular strength of the method is its ability to achieve quantified reconstructions in non-uniform illumination configurations resembling whole-body small animal imaging scenarios.
    Keywords: Engineering
    ISBN: 9780819475091
    ISSN: 0277-786X
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  • 4
    Language: English
    In: 2009 Asia Communications and Photonics conference and Exhibition (ACP), November 2009, pp.1-2
    Description: Fluorescence tomography can resolve fluorescence biodistribution in vivo with high sensitivity. We use structural information from X-ray CT as priors in the fluorescence reconstruction for improved accuracy, as shown previously [1]. The method was tested on different phantoms and animal models and cross-validated with XCT data, histology and ex vivo fluorescence.
    Keywords: Fluorescence ; Image Reconstruction ; Biomedical Optical Imaging ; Optical Imaging ; Biomedical Imaging ; Computed Tomography ; Animals ; X-Ray Imaging ; Optical Sensors ; In Vivo ; Engineering
    ISSN: 2162-108X
    E-ISSN: 2162-1098
    Source: IEEE Conference Publications
    Source: IEEE Xplore
    Source: IEEE Journals & Magazines 
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  • 5
    Language: English
    In: 09 July 2007, Vol.6631, pp.663110-663110-8
    Description: An optical detector suitable for inclusion in tomographic arrangements for non-contact in vivo bioluminescence and fluorescence imaging applications is proposed. It consists of a microlens array (MLA) intended for field-of-view definition, a large-field complementary metal-oxide-semiconductor (CMOS) chip for light detection, a septum mask for cross-talk suppression, and an exchangeable filter to block excitation light. Prototype detector units with sensitive areas of 2.5 cm x 5 cm each were assembled. The CMOS sensor constitutes a 512 x 1024 photodiode matrix at 48 μm pixel pitch. Refractive MLAs with plano-convex lenses of 480 μm in diameter and pitch were selected resulting in a 55 x 105 lens matrix. The CMOS sensor is aligned on the focal plane of the MLA at 2.15mm distance. To separate individual microlens images an opaque multi-bore septum mask of 2.1mm in thickness and bore diameters of 400 μm at 480 μm pitch, aligned with the lens pattern, is placed between MLA and CMOS. Intrinsic spatial detector resolution and sensitivity was evaluated experimentally as a function of detector-object distance. Due to its small overall dimensions such detectors can be favorably packed for tomographic imaging (optical diffusion tomography, ODT) yielding complete 2 π field-of-view coverage. We also present a design study of a device intended to simultaneously image positron labeled substrates (positron emission tomography, PET) and optical molecular probes in small animals such as mice and rats. It consists of a cylindrical allocation of optical detector units which form an inner detector ring while PET detector blocks are mounted in radial extension, those gaining complementary information in a single, intrinsically coregistered experimental data acquisition study. Finally, in a second design study we propose a method for integrated optical and magnetic resonance imaging (MRI) which yields in vivo functional/molecular information that is intrinsically registered with the anatomy of the image object.
    Keywords: Engineering
    ISBN: 9780819467751
    ISBN: 0819467758
    ISSN: 0277786X
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  • 6
    Language: English
    In: 09 July 2007, Vol.6631, pp.66311F-66311F-10
    Description: Recently, we have presented a thin optical detector assembly consisting of a microlens array (MLA) coupled to a large area CMOS sensor through a septum mask. The sensor is placed in the physical focal plane of the MLA. Each lens of the MLA forms a small image on the sensor surface, with individual images being separated from each other by the septum mask. The resulting sensor image thus shows a multitude of small sub-images. A low-resolution image can be attained by extracting only those pixels that are located on the optical axis of a microlens, as reported previously. Herein we describe an improved post-processing method to extract images of higher resolution (which can be focused to an arbitrary plane) from a single raw sensor image: Each lens of the MLA results in a mapping from points in object space to corresponding sensor pixels. By tracing back the light paths from sensor pixels through the lenses onto an arbitrary focal plane in object space this mapping can be inverted. Intensities captured on individual sensor pixels can be attributed to virtual pixels on that focal plane using the computed inverse mapping. As a result, from a single acquisition by the detector, images focused to any plane in object space can be calculated. In contrary to the approach of extracting focal point intensities, the spatial resolution is not limited by microlens pitch. We present experimental examples of extracted images at various object plane distances and studies determining the spatial resolution.
    Keywords: Engineering
    ISBN: 9780819467751
    ISBN: 0819467758
    ISSN: 0277786X
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  • 7
    Language: English
    In: 25 June 2007, Vol.6626, pp.66260N-66260N-6
    Description: Can time-resolved, high-resolution data as acquired by an intensified gated CCD camera (ICCD) aid in the tomographic reconstruction of fluorescence concentration? Usually it is argued that fluorescence is a linear process and thus does not require non-linear, time-dependent reconstructions algorithms, unless absorption and scattering coefficients need to be determined as well. Furthermore, the acquisition of a number of time frames is usually prohibitive for fluorescence measurements, at least in small animals, due to the increased total measurement time. On the other hand, it is obvious that diffusion is less pronounced in images at early gates, due to selective imaging of photons of lower scatter order. This will be the case also for photons emitted by fluorescent sources. Early-gated imaging might increase the contrast in acquired images and could possibly improve fluorescence localization. Herein, we present early gated fluorescence images obtained from phantoms and compare them to continuously acquired data. Increased contrast between background and signal maximum can be observed in time-gated images as compared to continuous data. To make use of the properties exhibited by early gated frames, it is necessary to use a modified reconstruction algorithm. We propose a variant of the well-known Born approximation to the diffusion equation that allows to take into account single time frames. The system matrix for the time-dependent Born approach is more complex to calculate, however the complexity of the actual inverse problem (and the acquisition times) of single-frame reconstructions remains the same as compared to continuous mode.
    Keywords: Medicine ; Visual Arts
    ISBN: 9780819467706
    ISBN: 0819467707
    ISSN: 0277786X
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  • 8
    Language: English
    In: Proceedings of SPIE, 30 June 2005, Vol.5859(1), pp.58590Z-58590Z-8
    Description: Non-contact detection schemes for optical or fluorescence tomography offer several advantages compared to classic approaches, most importantly the ability to obtain images with a CCD in the absence of a matching fluid or fiber optics. This allows the acquisition of high density datasets, as well as simplified experimental procedures. Herein we create a unified framework for contact and non-contact detection procedures and present experimental results that show the ability of the non-contact method to quantify the concentration of fluorochromes hidden in turbid media as well as the improvement in image quality between conventional and non-contact detection.
    Keywords: Engineering
    ISBN: 9780819458612
    ISSN: 0277-786X
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  • 9
    Language: English
    In: 2013 IEEE 18th Conference on Emerging Technologies & Factory Automation (ETFA), September 2013, pp.1-7
    Description: Field devices belong to the primary assets of an industrial plant. From the perspective of plant asset management, Computerized Maintenance Management Systems (CMMS) and Device Management Systems (DMS) share some responsibility for the well-being of these devices. CMMS and DMS reside on the opposite ends of the automation pyramid, have very different scopes, and there are multiple CMMS vendors that a DCS vendor might decide to support. Also, for each customer plant, the device/asset bases for both systems must be connected. The main goal is to avoid media breaks and offer a seamless workflow for the DCS users. In this article, we show how Field Device Integration (FDI) technology can serve to achieve and extend the deep, seamless integration of current solutions [2] through loose, light-weight coupling of DCS and CMMS.
    Keywords: Maintenance Engineering ; Coordinate Measuring Machines ; Software ; Automation ; Monitoring ; Standards ; Companies
    ISSN: 1946-0740
    E-ISSN: 1946-0759
    Source: IEEE Conference Publications
    Source: IEEE Xplore
    Source: IEEE Journals & Magazines 
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  • 10
    Language: English
    In: 2016 IEEE Information Theory Workshop (ITW), September 2016, pp.379-383
    Description: The large-system decoupling property of a MAP estimator is studied when it estimates the i.i.d. vector x from the observation y = Ax + z with A being chosen from a wide range of matrix ensembles, and the noise vector z being i.i.d. and Gaussian. Using the replica method, we show that the marginal joint distribution of any two corresponding input and output symbols converges to a deterministic distribution which describes the input-output distribution of a single user system followed by a MAP estimator. Under the bRSB assumption, the single user system is a scalar channel with additive noise where the noise term is given by the sum of an independent Gaussian random variable and b correlated interference terms. As the bRSB assumption reduces to RS, the interference terms vanish which results in the formerly studied RS decoupling principle.
    Keywords: Conferences ; Interference ; Additive Noise ; Glass ; Indexes ; Receivers ; Sensors
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