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  • 1. Cai, Fuhong
    et al.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Electric field Monte Carlo simulation of focused stimulated emission depletion beam, radially and azimuthally polarized beams for in vivo deep bioimaging2014Ingår i: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 19, nr 1, s. 011022-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An electric field Monte Carlo method is used to study the focal spot of a stimulated emission depletion (STED) beam, radially and azimuthally polarized beams in a turbid medium as a function of the scattering coefficient. To consider the diffraction of light of the wave nature, the wavefront is decomposed into a set of secondary spherical subwaves according to the Huygens principle. From the simulation results, we can find that the STED beam can still form a doughnut focal spot inside the turbid medium. These simulation results are important for the feasibility study of STED microscopy for in vivo deep bioimaging. Similarly, the focal spot for an azimuthally polarized beam can also keep a doughnut spot at the focal plane in a turbid medium.

  • 2. Cai, Fuhong
    et al.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Using graphics processing units to accelerate perturbation Monte Carlo simulation in a turbid medium2012Ingår i: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 17, nr 4, s. 040502-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report a fast perturbation Monte Carlo (PMC) algorithm accelerated by graphics processing units (CPU). The two-step PMC simulation [Opt. Lett. 36, 2095 (2011)] is performed by storing the seeds instead of the photon's trajectory, and thus the requirement in computer random-access memory (RAM) becomes minimal. The two-step PMC is extremely suitable for implementation onto CPU. In a standard simulation of spatially-resolved photon migration in the turbid media, the acceleration ratio between using GPU and using conventional CPU is about 1000. Furthermore, since in the two-step PMC algorithm one records the effective seeds, which is associated to the photon that reaches a region of interest in this letter, and then re-run the MC simulation based on the recorded effective seeds, radiative transfer equation (RTE) can be solved by two-step PMC not only with an arbitrary change in the absorption coefficient, but also with large change in the scattering coefficient.

  • 3. Cai, Fuhong
    et al.
    Qian, Jun
    Jiang, Li
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Multifunctional optical imaging using dye-coated gold nanorods in a turbid medium2011Ingår i: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 16, nr 1, s. 016002-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report multifunctional optical imaging using dye-coated gold nanorods. Three types of useful information, namely, Raman, fluorescence signals, and absorption contrast, can be obtained from a phantom experiment. These three kinds of information are detected in a nanoparticle-doped-phantom using diffuse optical imaging. Our novel nanoparticle could be used as a multimodality marker for future bioimaging applications.

  • 4.
    Etcheverry, Sebastián
    et al.
    Universidad de Concepción, Chile .
    Gallado, Maria Jose
    Solano, Pablo
    Suwalsky, Mario
    Mesquita, Oscar
    Saavedra, Carlos
    Real-time study of shape and thermal fluctuations in the echinocyte transformation of human erythrocytes using defocusing microscopy2012Ingår i: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 17, nr 10, s. 106013-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a real-time method to measure the amplitude of thermal fluctuations in biological membranes by means of a new treatment of the defocusing microscopy (DM) optical technique. This approach was also applied to study the deformation of human erythrocytes to its echinocyte structure. This was carried out by making three-dimensional shape reconstructions of the cell and measuring the thermal fluctuations of its membrane, as the cell is exposed to the anti-inflammatory drug naproxen and as it recovers its original shape, when it is subsequently cleansed of the drug. The results showed biomechanical changes in the membrane even at low naproxen concentration (0.2 mM). Also, we found that when the cell recovered its original shape, the membrane properties were different compared to the nondrugged initial erythrocyte, indicating that the drug administration-recovery process is not completely reversible.

  • 5. Gosch, M.
    et al.
    Blom, Hans
    Anderegg, S.
    Korn, K.
    Thyberg, P.
    Wells, M.
    Lasser, T.
    Rigler, R.
    Parallel dual-color fluorescence cross-correlation spectroscopy using diffractive optical elements2005Ingår i: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 10, nr 5Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Dual-color cross-correlation spectroscopy allows the detection and quantification of labeled biomolecules at ultra-low concentrations, whereby the sensitivity of the assay correlates with the measurement time. We now describe a parallel multifocal dual-color spectroscopic configuration employing multiple avalanche photodiodes and hardware correlators. Cross-correlation curves are obtained from several dual-color excitation foci simultaneously. Multifocal dual-color excitation is achieved by splitting each of two laser beams (488 and 633 nm) into four sub-beams with the help of two 2 X 2 fan-out diffractive optical elements (DOES), and subsequent superposition of the two sets of four foci. The fluorescence emission from double-labeled biomolecules is detected by two 2 x 2 fiber arrays.

  • 6. Gosch, M.
    et al.
    Serov, A.
    Anhut, T.
    Lasser, T.
    Rochas, A.
    Besse, P. A.
    Popovic, R. S.
    Blom, Hans
    KTH, Tidigare Institutioner, Fysik.
    Rigler, R.
    Parallel single molecule detection with a fully integrated single-photon 2X2 CMOS detector array2004Ingår i: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 9, nr 5, s. 913-921Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present parallel single molecule detection (SMD) and fluorescence correlation spectroscopy (FCS) experiments with a fully integrated complementary metal oxide semiconductor (CMOS) single-photon 2 X 2 detector array. Multifocal excitation is achieved with a diffractive optical element (DOE). Special emphasis is placed on parallelization of the total system. The performance of the novel single-photon CMOS detector is investigated and compared to a state-of-the-art single-photon detecting module [having an actively quenched avalanche photodiode (APD)] by measurements on free diffusing molecules at different concentrations. Despite the order of magnitude lower detection efficiency of the CMOS detector compared to the state-of-the-art single-photon detecting module, we achieve single molecule sensitivity and reliably determine molecule concentrations. In addition, the CMOS detector performance for the determination of the fraction of slowly diffusing molecules in a primer solution (two-component analysis) is demonstrated. The potential of this new technique for high-throughput confocal-detection-based systems is discussed.

  • 7. Leutenegger, Marcel
    et al.
    Blom, Hans
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Experimentell biomolekylär fysik.
    Widengren, Jerker
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Experimentell biomolekylär fysik.
    Eggeling, Christian
    Goesch, Michael
    Leitgeb, Rainer A.
    Lasser, Theo
    Dual-color total internal reflection fluorescence cross-correlation spectroscopy2006Ingår i: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 11, nr 4Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present the development and first application of a novel dual-color total internal reflection (TIR) fluorescence system for single-molecule coincidence analysis and fluorescence cross-correlation spectroscopy (FCCS). As a performance analysis, we measured a synthetic DNA-binding assay, demonstrating this dual-color TIR-FCCS approach to be a suitable method for measuring coincidence assays such as biochemical binding, fusion, or signal transduction at solid/liquid interfaces. Due to the very high numerical aperture of the epi-illumination configuration, our setup provides a very high fluorescence collection efficiency resulting in a two- to three- fold increase in molecular brightness compared to conventional confocal FCCS. Further improvements have been achieved through global analysis of the spectroscopic data.

  • 8.
    Lundström, Linda
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Unsbo, Peter
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Gustafsson, Jörgen
    Lund University, Certec, Rehabilitation Engineering Research, Department of Design Sciences, Lund.
    Off-axis wave front measurements for optical correction in eccentric viewing2005Ingår i: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 10, nr 3, s. 034002-1-034002-7Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In a previous study we have shown that correction of peripheral refractive errors can improve the remaining vision of subjects with large central visual field loss. Measuring peripheral refractive errors with traditional methods is often difficult due to low visual acuity and large aberrations. Therefore a Hartmann-Shack sensor has been designed to measure peripheral wave front aberrations in subjects using eccentric viewing. The sensor incorporates an eye tracker and analyzing software designed to handle large wave front aberrations and elliptic pupils. To ensure that the measurement axis is aligned with the direction of the subject's preferred retinal location, a special fixation target has been developed. It consists of concentric rings surrounding the aperture of the sensor together with a central fixation mark along the measurement axis. Some initial measurements on subjects using eccentric viewing have been performed successfully. As a first step in improving the peripheral optics of the eye, the wave front has been used to calculate the eccentric refraction. This refraction has been compared to the refraction found with the Power-Refractor instrument. Measuring the off-axis wave front is a fast way to assess the optical errors in the subject's eccentric viewing angle and to better understand the problems of eccentric correction.

  • 9.
    Qian, Jun
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Gharibi, Arash
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    He, Sailing
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Colloidal mesoporous silica nanoparticles with protoporphyrin IX encapsulated for photodynamic therapy2009Ingår i: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 14, nr 1Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Protoporphyrin IX (PpIX)-encapsulated mesoporous silica nanoparticles were synthesized, characterized, and utilized for photodynamic therapy (PDT) of cancer. Silica encapsulation is relatively transparent for activated light and can protect the PpIX against denaturation induced by the extreme bioenvironment. The mesoporous silica can also ensure that the encapsulated PpIX can be well-contacted with oxygen, stimulated, and released. PpIX-encapsulated colloidal mesoporous silica nanoparticles were uptaken by tumor cells in vitro, and the effect of photon-induced toxicity was demonstrated after comparison with some control experiments. The surface of PpIX-encapsulated silica nanoparticles can be grafted with appropriate functionalized groups and conjugated with certain biomolecules for specific targeting.

  • 10. Ughi, Giovanni J.
    et al.
    Adriaenssens, Tom
    Larsson, Matilda
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik.
    Dubois, Christophe
    Sinnaeve, Peter R.
    Coosemans, Mark
    Desmet, Walter
    D'hooge, Jan
    Automatic three-dimensional registration of intravascular optical coherence tomography images2012Ingår i: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 17, nr 2, s. 026005-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Intravascular optical coherence tomography (IV-OCT) is a catheter-based high-resolution imaging technique able to visualize the inner wall of the coronary arteries and implanted devices in vivo with an axial resolution below 20 mu m. IV-OCT is being used in several clinical trials aiming to quantify the vessel response to stent implantation over time. However, stent analysis is currently performed manually and corresponding images taken at different time points are matched through a very labor-intensive and subjective procedure. We present an automated method for the spatial registration of IV-OCT datasets. Stent struts are segmented through consecutive images and three-dimensional models of the stents are created for both datasets to be registered. The two models are initially roughly registered through an automatic initialization procedure and an iterative closest point algorithm is subsequently applied for a more precise registration. To correct for nonuniform rotational distortions (NURDs) and other potential acquisition artifacts, the registration is consecutively refined on a local level. The algorithm was first validated by using an in vitro experimental setup based on a polyvinyl-alcohol gel tubular phantom. Subsequently, an in vivo validation was obtained by exploiting stable vessel landmarks. The mean registration error in vitro was quantified to be 0.14 mm in the longitudinal axis and 7.3-deg mean rotation error. In vivo validation resulted in 0.23 mm in the longitudinal axis and 10.1-deg rotation error. These results indicate that the proposed methodology can be used for automatic registration of in vivo IV-OCT datasets. Such a tool will be indispensable for larger studies on vessel healing pathophysiology and reaction to stent implantation. As such, it will be valuable in testing the performance of new generations of intracoronary devices and new therapeutic drugs.

  • 11.
    Ughi, Giovanni J.
    et al.
    Katholieke Univ Leuven, Dept Cardiovasc Sci, B-3000 Louvain, Belgium..
    Adriaenssens, Tom
    Katholieke Univ Leuven Hosp, Dept Cardiovasc Sci, B-3000 Louvain, Belgium..
    Larsson, Matilda
    KTH.
    Dubois, Christophe
    Katholieke Univ Leuven, Dept Cardiovasc Sci, B-3000 Louvain, Belgium.;Katholieke Univ Leuven Hosp, Dept Cardiovasc Sci, B-3000 Louvain, Belgium..
    Sinnaeve, Peter R.
    Katholieke Univ Leuven, Dept Cardiovasc Sci, B-3000 Louvain, Belgium.;Katholieke Univ Leuven Hosp, Dept Cardiovasc Sci, B-3000 Louvain, Belgium..
    Coosemans, Mark
    Katholieke Univ Leuven Hosp, Dept Cardiovasc Sci, B-3000 Louvain, Belgium..
    Desmet, Walter
    Katholieke Univ Leuven, Dept Cardiovasc Sci, B-3000 Louvain, Belgium.;Katholieke Univ Leuven Hosp, Dept Cardiovasc Sci, B-3000 Louvain, Belgium..
    D'hooge, Jan
    Katholieke Univ Leuven, Dept Cardiovasc Sci, B-3000 Louvain, Belgium..
    Erratum to: Automatic three-dimensional registration of intravascular optical coherence tomography images2012Ingår i: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 17, nr 4, artikel-id 049803Artikel i tidskrift (Refereegranskat)
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