Raphael André

Master-Student



Uni- München

Email:
Phone:
Fax:

Publikationen

2017

  • Laves, Max-Heinrich and Schoob, Andreas and Kahrs, Lüder A. and Pfeiffer, Tom and Huber, Robert and Ortmaier, Tobias: Feature tracking for automated volume of interest stabilization on 4D-OCT images. in Proc. SPIE, no. 10135, pp. 101350W-101350W-7, 2017
    BibTeX Link
    @inproceedings{Laves2017,
       author = {Laves, Max-Heinrich and Schoob, Andreas and Kahrs, Lüder A. and Pfeiffer, Tom and Huber, Robert and Ortmaier, Tobias},
       title = {Feature tracking for automated volume of interest stabilization on 4D-OCT images},
     booktitle = {Proc. SPIE},
       volume = {10135},
       pages = {101350W-101350W-7},
      year = {2017},
       url = {http://dx.doi.org/10.1117/12.2255090},
       type = {Conference Proceedings}
    }
    

2015

  • Steiner, Patrick and Ebneter, Andreas and Berger, Lieselotte Erika and Zinkernagel, Martin and Považay, Boris and Meier, Christoph and Kowal, Jens H. and Framme, Carsten and Brinkmann, Ralf and Wolf, Sebastian and Sznitman, Raphael: Time-Resolved Ultra–High Resolution Optical Coherence Tomography for Real-Time Monitoring of Selective Retina TherapyTime-Resolved Ultra–High Resolution OCT During SRT. Investigative Ophthalmology & Visual Science, no. 56, pp. 6654-6662, 2015
    BibTeX Link
    @article{Steiner2015,
       author = {Steiner, Patrick and Ebneter, Andreas and Berger, Lieselotte Erika and Zinkernagel, Martin and Považay, Boris and Meier, Christoph and Kowal, Jens H. and Framme, Carsten and Brinkmann, Ralf and Wolf, Sebastian and Sznitman, Raphael},
       title = {Time-Resolved Ultra–High Resolution Optical Coherence Tomography for Real-Time Monitoring of Selective Retina TherapyTime-Resolved Ultra–High Resolution OCT During SRT},
       journal = {Investigative Ophthalmology & Visual Science},
       volume = {56},
       number = {11},
       pages = {6654-6662},
       note = {10.1167/iovs.15-17151},
       abstract = {Abstract Purpose: Selective retina therapy (SRT) is a novel treatment for retinal pathologies, solely targeting the RPE. During SRT, the detection of an immediate tissue reaction is challenging, as tissue effects remain limited to intracellular RPE photodisruption. Time-resolved ultra-high axial resolution optical coherence tomography (OCT) is thus evaluated for the monitoring of dynamic optical changes at and around the RPE during SRT. Methods: An experimental OCT system with an ultra-high axial resolution of 1.78 μm was combined with an SRT system and time-resolved OCT M-scans of the target area were recorded from four patients undergoing SRT. Optical coherence tomography scans were analyzed and OCT morphology was correlated with findings in fluorescein angiography, fundus photography, and cross-sectional OCT. Results: In cases in which the irradiation caused RPE damage proven by fluorescein angiography, the lesions were well discernible in time-resolved OCT images but remained invisible in fundus photography and cross-sectional OCT acquired after treatment. If RPE damage was introduced, all applied SRT pulses led to detectable signal changes in the time-resolved OCT images. The extent of optical signal variation seen in the OCT data appeared to scale with the applied SRT pulse energy. Conclusions: The first clinical results proved that successful SRT irradiation induces detectable changes in the OCT M-scan signal while it remains invisible in conventional ophthalmoscopic imaging. Thus, real-time high-resolution OCT is a promising modality to monitor and analyze tissue effects introduced by selective retina therapy and may be used to guide SRT in an automatic feedback mode (www.swissmedic.ch number, 2011-MD-0006).},
       ISSN = {1552-5783},
       DOI = {10.1167/iovs.15-17151},
       year = {2015},
       type = {Journal Article}
    }
    

2013

  • Klein, Thomas and Andre, Raphael and Wieser, Wolfgang and Pfeiffer, Tom and Huber, Robert: Joint aperture detection for speckle reduction and increased collection efficiency in ophthalmic MHz OCT. Biomedical optics express, no. 4, pp. 619-34, apr,, 2013
    BibTeX Link
    @Article{HU_2013_Klein_b,
      Title                    = {{Joint aperture detection for speckle reduction and increased collection efficiency in ophthalmic MHz OCT}},
      Author                   = {Klein, Thomas and Andre, Raphael and Wieser, Wolfgang and Pfeiffer, Tom and Huber, Robert},
      Journal                  = {Biomedical optics express},
      Year                     = {2013},
    
      Month                    = apr,
      Number                   = {4},
      Pages                    = {619--34},
      Volume                   = {4},
    
      Doi                      = {10.1364/BOE.4.000619},
      ISSN                     = {2156-7085},
      Url                      = {http://www.opticsinfobase.org/boe/abstract.cfm?uri=boe-4-4-619}
    }
  • Trost, Andrea and Schroedl, Falk and Strohmaier, Clemens A and Bogner, Barbara and Runge, Christian and Kaser-Eichberger, Alexandra and Krefft, Karolina Anna and Vogel, Alfred and Linz, Norbert and Freidank, Sebastian and Hilpert, Andrea and Zimmermann, Inge and Grabner, Günther and Reitsamer, Herbert A: A new nanosecond UV-laser at 355 nm: early results of corneal flap cutting in a rabbit model. Investigative Ophthalmology & Visual Science, 2013
    BibTeX Link
    @article{Trost2013,
       author = {Trost, Andrea and Schroedl, Falk and Strohmaier, Clemens A and Bogner, Barbara and Runge, Christian and Kaser-Eichberger, Alexandra and Krefft, Karolina Anna and Vogel, Alfred and Linz, Norbert and Freidank, Sebastian and Hilpert, Andrea and Zimmermann, Inge and Grabner, Günther and Reitsamer, Herbert A},
       title = {A new nanosecond UV-laser at 355 nm: early results of corneal flap cutting in a rabbit model},
       journal = {Investigative Ophthalmology & Visual Science},
       abstract = {Purpose: A new 355nm UV laser was used for corneal flap cutting in an animal model and tested for clinical and morphological alterations. Methods: Corneal flaps were created (Chinchilla Bastards; n=25) with an UV-nanosecond laser at 355nm (150kHz, pulse duration 850ps, spot-size 1µm, spot-spacing 6x6µm, side-cut Δz 1µm; cutting depth 130µm) and pulse energies of 2.2 or 2.5µJ, respectively. Following slit lamp examination, animals were sacrificed at 6, 12 and 24hrs after treatment. Corneas were prepared for histology (HE, TUNEL-assay) and evaluated statistically, followed by ultrastructural investigations. Results: Laser treatment was tolerated well, flap lift was easier at 2.5µJ compared to 2.2µJ. Standard HE at 24hrs revealed intact epithelium in the horizontal cut, with similar increase in corneal thickness at both energies. Irrespective of energy levels, TUNEL assay revealed comparable numbers of apoptotic cells in the horizontal and vertical cut at 6/12/24hrs, becoming detectable in the horizontal cut as an acellular stromal band at 24hrs. Ultrastructural analysis revealed regular morphology in the epi- and endothelium, while in the stroma, disorganized collagen lamellae were detectable representing the horizontal cut, again irrespective of energy levels applied. Conclusions:This new UV-laser revealed no epithelial nor endothelial damage at energies feasible for corneal flap cutting. Observed corneal swelling was lower compared to existing UV-lasers-studies, albeit total energy applied here was much higher. Observed loss of stromal keratinocytes is comparable to available laser systems. Therefore, this new laser is suitable for refractive surgery, awaiting its test in a chronic environment.},
       DOI = {10.1167/iovs.13-12580},
       url = {http://www.iovs.org/content/early/2013/10/28/iovs.13-12580.abstract},
       year = {2013},
       type = {Journal Article}
    }
    

2012

  • Blatter, Cedric and Klein, Thomas and Grajciar, Branislav and Schmoll, Tilman and Wieser, Wolfgang and Andre, Raphael and Huber, Robert and Leitgeb, Rainer A: Ultrahigh-speed non-invasive widefield angiography. Journal of biomedical optics, no. 17, pp. 070505 1-3, jul,, 2012
    BibTeX Link
    @Article{HU_2012_Blatter_c,
      Title                    = {{Ultrahigh-speed non-invasive widefield angiography}},
      Author                   = {Blatter, Cedric and Klein, Thomas and Grajciar, Branislav and Schmoll, Tilman and Wieser, Wolfgang and Andre, Raphael and Huber, Robert and Leitgeb, Rainer A},
      Journal                  = {Journal of biomedical optics},
      Year                     = {2012},
    
      Month                    = jul,
      Number                   = {7},
      Pages                    = {070505 1--3 },
      Volume                   = {17},
    
      Doi                      = {10.1117/1.JBO.17.7.070505},
      ISSN                     = {1560-2281},
      Url                      = {http://biomedicaloptics.spiedigitallibrary.org/article.aspx?articleid=1351611}
    }
  • Klein, Thomas and Wieser, Wolfgang and Andre, Raphael and Pfeiffer, Tom and Eigenwillig, Christoph M and Huber, Robert: Multi-MHz FDML OCT: snapshot retinal imaging at 6.7 million axial-scans per second. in SPIE BiOS, pp. 82131E 1-3, International Society for Optics and Photonics, feb,, 2012
    BibTeX Link
    @InProceedings{HU_2012_Klein_b,
      Title                    = {{Multi-MHz FDML OCT: snapshot retinal imaging at 6.7 million axial-scans per second}},
      Author                   = {Klein, Thomas and Wieser, Wolfgang and Andre, Raphael and Pfeiffer, Tom and Eigenwillig, Christoph M and Huber, Robert},
      Booktitle                = {SPIE BiOS},
      Year                     = {2012},
      Editor                   = {Izatt, Joseph A and Fujimoto, James G and Tuchin, Valery V},
      Month                    = feb,
      Pages                    = {82131E 1--3 },
      Publisher                = {International Society for Optics and Photonics},
    
      Doi                      = {10.1117/12.908798},
      Url                      = {http://proceedings.spiedigitallibrary.org/proceeding.aspx?doi=10.1117/12.908798}
    }

2011

  • Orzekowsky-Schroeder, Regina and Klinger, Antje and Martensen, Bjorn and Blessenohl, Maike and Gebert, Andreas and Vogel, Alfred and Huttmann, Gereon: In vivo spectral imaging of different cell types in the small intestine by two-photon excited autofluorescence. Journal of Biomedical Optics, no. 16, pp. 116025, 2011
    BibTeX
    @article{Orzekowsky2011,
       author = {Orzekowsky-Schroeder, Regina and Klinger, Antje and Martensen, Bjorn and Blessenohl, Maike and Gebert, Andreas and Vogel, Alfred and Huttmann, Gereon},
       title = {In vivo spectral imaging of different cell types in the small intestine by two-photon excited autofluorescence},
       journal = {Journal of Biomedical Optics},
       volume = {16},
       number = {11},
       pages = {116025},
       keywords = {biological organs
    biomedical optical imaging
    cellular biophysics
    fluorescence
    laser applications in medicine
    two-photon processes},
       year = {2011}
    }

2009

  • Lachmann, Kristina and Eckert, Sebastian and Vogel, Alfred and Klinger, Antje and Gebert, Andreas and Klages, Claus-Peter: Development of a multifunctional coating system for laser-induced material transport. Progress in Organic Coatings, no. 64, pp. 294-299, 2009
    BibTeX
    @article{Lachmann,
       author = {Lachmann, Kristina and Eckert, Sebastian and Vogel, Alfred and Klinger, Antje and Gebert, Andreas and Klages, Claus-Peter},
       title = {Development of a multifunctional coating system for laser-induced material transport},
       journal = {Progress in Organic Coatings},
       volume = {64},
       number = {2–3},
       pages = {294-299},
       abstract = {The aim of our research is to develop a novel surface coating for the use in laser microdissection and laser pressure catapulting (LMPC). LMPC is a contact- and contamination-free technique to separate histologic material and living cells for further proteomic and genomic analysis. Several physico-chemical functions must be included within the optimum coating system designed for this purpose, like optical absorption at the laser wavelength, combined with optical transparency in the visible region, a control of the laser ablation process, mechanical stability and biocompability for the adhesion of the histologic material. To achieve the optimum system the combination of several layers is required. The optical absorbance to capture the radiation energy from a frequency-tripled Nd:YAG laser (? = 355 nm) is reached by a thin layer of zinc oxide (ZnO), deposited by hollow cathode gas flow sputtering. The laser ablation process is controlled by a polyelectrolyte multilayer, consisting of poly(diallyldimethylammonium chloride) (PDADMAC) and poly(sodium 4-styrenesulfonate) (PSS). The evaporation of chemisorbed water from the film is used to promote the catapulting process. For the mechanically stable, laser-dissectible layer organic coatings, like photoresists or lacquers, are suitable. Silica-containing polyacrylate nanocomposites were employed for this purpose. The investigation of the coating system included LMPC experiments with varying compositions of the layer system. The best results were obtained using a system consisting of ZnO, a polyelectrolyte multilayer deposited from 0.1 M Na2SO4 containing polymer solutions, and a 1.5-?m thick layer of the polyacrylate nanocomposite. To check the quality of the developed system, experiments with the commonly used poly(ethylene naphthalate) (PEN) foil were performed simultaneously. In addition to the determination of the parameters required for LMPC, quantitative real-time Polymerase Chain Reaction (rt-PCR) of the dissected material verified the benefit of the new system.},
       keywords = {Laser microdissection
    Laser pressure catapulting
    Polyelectrolyte multilayer
    Laser ablation
    Zinc oxide},
       year = {2009}
    }

2008

  • Andrews, Peter M and Chen, Yu and Onozato, Maristela L and Huang, Shu-Wei and Adler, Desmond C and Huber, Robert A and Jiang, James and Barry, Scott E and Cable, Alex E and Fujimoto, James G: High-resolution optical coherence tomography imaging of the living kidney. Laboratory investigation; a journal of technical methods and pathology, no. 88, pp. 441-9, apr,, 2008
    BibTeX Link
    @Article{HU_2008_Andrews_a,
      Title                    = {{High-resolution optical coherence tomography imaging of the living kidney}},
      Author                   = {Andrews, Peter M and Chen, Yu and Onozato, Maristela L and Huang, Shu-Wei and Adler, Desmond C and Huber, Robert A and Jiang, James and Barry, Scott E and Cable, Alex E and Fujimoto, James G},
      Journal                  = {Laboratory investigation; a journal of technical methods and pathology},
      Year                     = {2008},
    
      Month                    = apr,
      Number                   = {4},
      Pages                    = {441--9},
      Volume                   = {88},
    
      Doi                      = {10.1038/labinvest.2008.4},
      ISSN                     = {1530-0307},
      Url                      = {http://www.nature.com/labinvest/journal/v88/n4/full/labinvest20084a.html}
    }

2007

  • Ramrath, Lukas and Hofmann, UlrichG and Huettmann, Gereon and Moser, Andreas and Schweikard, Achim: Towards Automated OCT-based Identification of White Brain Matter. in Bildverarbeitung für die Medizin 2007, pp. 414-418, Springer Berlin Heidelberg, 2007
    BibTeX
    @inbook{Ramrath,
       author = {Ramrath, Lukas and Hofmann, UlrichG and Huettmann, Gereon and Moser, Andreas and Schweikard, Achim},
       title = {Towards Automated OCT-based Identification of White Brain Matter},
       booktitle = {Bildverarbeitung für die Medizin 2007},
       editor = {Horsch, Alexander and Deserno, ThomasM and Handels, Heinz and Meinzer, Hans-Peter and Tolxdorff, Thomas},
       series = {Informatik aktuell},
       publisher = {Springer Berlin Heidelberg},
       chapter = {83},
       pages = {414-418},
       year = {2007}
    }
  • Vogel, Alfred and Lorenz, Kathrin and Horneffer, Verena and Hüttmann, Gereon and Von Smolinski, Dorthe and Gebert, Andreas: Mechanisms of laser-induced dissection and transport of histologic specimens. Biophysical journal, no. 93, pp. 4481-4500, 2007
    BibTeX
    @article{Vogel2007,
       author = {Vogel, Alfred and Lorenz, Kathrin and Horneffer, Verena and Hüttmann, Gereon and Von Smolinski, Dorthe and Gebert, Andreas},
       title = {Mechanisms of laser-induced dissection and transport of histologic specimens},
       journal = {Biophysical journal},
       volume = {93},
       number = {12},
       pages = {4481-4500},
       ISSN = {0006-3495},
       year = {2007},
       type = {Journal Article}
    }
    
  • Kranendonk, Laura A and An, Xinliang and Caswell, Andrew W and Herold, Randy E and Sanders, Scott T and Huber, Robert and Fujimoto, James G and Okura, Yasuhiro and Urata, Yasuhiro: High speed engine gas thermometry by Fourier-domain mode-locked laser absorption spectroscopy. Optics Express, no. 15, pp. 15115 - 15128, nov,, 2007
    BibTeX Link
    @Article{HU_2007_Kranendonk_a,
      Title                    = {{High speed engine gas thermometry by Fourier-domain mode-locked laser absorption spectroscopy}},
      Author                   = {Kranendonk, Laura A and An, Xinliang and Caswell, Andrew W and Herold, Randy E and Sanders, Scott T and Huber, Robert and Fujimoto, James G and Okura, Yasuhiro and Urata, Yasuhiro},
      Journal                  = {Optics Express},
      Year                     = {2007},
    
      Month                    = nov,
      Number                   = {23},
      Pages                    = {15115 -- 15128 },
      Volume                   = {15},
    
      Doi                      = {10.1364/OE.15.015115},
      ISSN                     = {1094-4087},
      Url                      = {http://www.opticsinfobase.org/abstract.cfm?URI=oe-15-23-15115}
    }

2005

  • Sharma, Vikas and Kowalevicz Jr., Andrew M and Huber, Robert and Fujimoto, James G and Minoshima, Kaoru: Three Dimensional Waveguide Splitters Fabricated in Glass Using a Femtosecond Laser Oscillator - Technical Digest (CD). in Conference on Lasers and Electro-Optics/Quantum Electronics and Laser Science and Photonic Applications Systems Technologies, pp. CThCC4, Optical Society of America, 2005
    BibTeX Link
    @InProceedings{HU_2005_Sharma_a,
      Title                    = {{Three Dimensional Waveguide Splitters Fabricated in Glass Using a Femtosecond Laser Oscillator - Technical Digest (CD)}},
      Author                   = {Sharma, Vikas and {Kowalevicz Jr.}, Andrew M and Huber, Robert and Fujimoto, James G and Minoshima, Kaoru},
      Booktitle                = {Conference on Lasers and Electro-Optics/Quantum Electronics and Laser Science and Photonic Applications Systems Technologies},
      Year                     = {2005},
      Pages                    = {CThCC4},
      Publisher                = {Optical Society of America},
    
      Url                      = {http://www.opticsinfobase.org/abstract.cfm?URI=CLEO-2005-CThCC4}
    }

1995

  • Reichle, A. and Diddens, H. and Altmayr, F. and Rastetter, J. and Andreesen, R.: Beta-tubulin and P-glycoprotein: Major determinants of vincristine accumulation in B-CLL cells. Leuk Res, no. 19, pp. 823-829, 1995
    BibTeX
    @article{Reichle,
       author = {Reichle, A. and Diddens, H. and Altmayr, F. and Rastetter, J. and Andreesen, R.},
       title = {Beta-tubulin and P-glycoprotein: Major determinants of vincristine accumulation in B-CLL cells},
       journal = {Leuk Res},
       volume = {19},
       number = {11},
       pages = {823-829},
       abstract = {Vincristine (VCR) accumulation in chronic lymphatic leukemia of B-cell origin (B-CLL) has recently been shown not to be inversely correlated to P-glycoprotein (PGP) levels. Therefore, we studied, in addition to PGP expression and accumulation of VCR, the cellular ?-tubulin content in quiescent and rhIL-2 activated B-CLL cells. VCR mediates cytotoxicity by binding to tubulin. Constitutive ?-tubulin levels in B-CLL cells varied considerably. Upon activation with rhIL-2, ?-tubulin expression increased significantly. Therefore, tubulin levels could be correlated over a wide range to VCR accumulation. When the PGP-mediated drug efflux was blocked by verapamil (VRP), tubulin levels correlated linearly to VCR accumulation. All B-CLL cases expressed PGP at different levels. There was no linear correlation between PGP expression and VCR accumulation. A modulation factor m was defined as a quotient of VCR accumulation in the presence and absence of VRP to define the extent by which VRP inhibited a steady-state accumulation of VCR. The factor allowed discrimination between B-CLLs expressing low versus high PGP, irrespective of the levels of tubulin. However, PGP and ?-tubulin levels together were predictive for VCR accumulation in steady state. There was no uniform accumulation defect for VCR in B-cell CLL because ?-tubulin and PGP were expressed independently. Non PGP-mediated VCR transport seems to play a minor role in B-cell CLL. Leukemia-associated varying of cytoskeletal organization in B-cell CLL might be one reason for the diverse cellular responses to receptor-mediated signals.},
       keywords = {Multidrug resistance
    tubulin
    vincristine
    B-CLL},
       year = {1995}
    }
    

1994

  • Reichle, A. and Diddens, H. and Altmayr, F. and Rastetter, J. and Andreesen, R.: Chemomodulation of drugs involved in multiple resistance in chronic lymphatic leukemia of the B-cell type. Cancer Chemother Pharmacol., no. 34, pp. 307-16, 1994
    BibTeX
    @article{Reichle,
       author = {Reichle, A. and Diddens, H. and Altmayr, F. and Rastetter, J. and Andreesen, R.},
       title = {Chemomodulation of drugs involved in multiple resistance in chronic lymphatic leukemia of the B-cell type},
       journal = {Cancer Chemother Pharmacol.
    },
       volume = {34},
       number = {4},
       pages = {307-16},
       year = {1994}
    }
    

  • Orzekowsky-Schroeder, Regina and Klinger, Antje and Schuth, Anna and Freidank, Sebastian and Huttmann, Gereon and Gebert, Andreas and Vogel, Alfred: Intravital real-time study of tissue response to controlled laser-induced cavitation using 500-ps UV laser pulses focused in murine gut mucosa under online dosimetry and spectrally resolved 2-photon microscopy. no. 7568, pp. 756815, SPIE,
    BibTeX
    @inproceedings{Orzekowsky2010,
       author = {Orzekowsky-Schroeder, Regina and Klinger, Antje and Schuth, Anna and Freidank, Sebastian and Huttmann, Gereon and Gebert, Andreas and Vogel, Alfred},
       title = {Intravital real-time study of tissue response to controlled laser-induced cavitation using 500-ps UV laser pulses focused in murine gut mucosa under online dosimetry and spectrally resolved 2-photon microscopy},
       editor = {Daniel, L. Farkas and Dan, V. Nicolau and Robert, C. Leif},
       publisher = {SPIE},
       volume = {7568},
       pages = {756815},
    
    }
  • Stoehr, Hardo and Ptaszynski, Lars and Fritz, Andreas and Brinkmann, Ralf: Interferometric optical online dosimetry for selective retina treatment (SRT). no. 6426, pp. 642619-642619-7,
    BibTeX Link
    @inproceedings{Stoehr2007,
       author = {Stoehr, Hardo and Ptaszynski, Lars and Fritz, Andreas and Brinkmann, Ralf},
       title = {Interferometric optical online dosimetry for selective retina treatment (SRT)},
       volume = {6426},
       pages = {642619-642619-7},
       note = {10.1117/12.708521},
       abstract = {In selective retina treatment (SRT) spatial confined tissue damage in the absorbing retinal pigment epithelium (RPE) is obtained by applying microsecond laser pulses. The damage in the RPE is caused by transient microbubbles forming around the laser heated melanin granules inside the cells. For treatment of RPE related diseases, SRT is thought to share the therapeutic benefits of conventional photocoagulation but without affecting the photoreceptors. A drawback for effective clinical SRT is that the laser-induced lesions are ophthalmoscopically invisible. Therefore, a real-time feedback system for dosimetry is demanded in order to avoid undertreatment or unwanted collateral damage to the adjacent tissue. We develop a dosimetry system which uses optical interferometry for the detection of the transient microbubbles. The system is based on an optical fiber interferometer which is operated with a laser diode at 830nm. We present current results obtained with porcine RPE explants in vitro and complete porcine eye globes ex vivo.},
       url = {http://dx.doi.org/10.1117/12.708521},
       type = {Conference Proceedings}
    }
    
  • Stoehr, Hardo and Ptaszynski, Lars and Fritz, Andreas and Brinkmann, Ralf: Interferometric optical online dosimetry for selective retina treatment (SRT). no. 6426, pp. 642619-642619-7,
    BibTeX
    @inproceedings{Stoehr2007,
       author = {Stoehr, Hardo and Ptaszynski, Lars and Fritz, Andreas and Brinkmann, Ralf},
       title = {Interferometric optical online dosimetry for selective retina treatment (SRT)},
       volume = {6426},
       pages = {642619-642619-7},
       note = {10.1117/12.708521},
       abstract = {In selective retina treatment (SRT) spatial confined tissue damage in the absorbing retinal pigment epithelium (RPE) is obtained by applying microsecond laser pulses. The damage in the RPE is caused by transient microbubbles forming around the laser heated melanin granules inside the cells. For treatment of RPE related diseases, SRT is thought to share the therapeutic benefits of conventional photocoagulation but without affecting the photoreceptors. A drawback for effective clinical SRT is that the laser-induced lesions are ophthalmoscopically invisible. Therefore, a real-time feedback system for dosimetry is demanded in order to avoid undertreatment or unwanted collateral damage to the adjacent tissue. We develop a dosimetry system which uses optical interferometry for the detection of the transient microbubbles. The system is based on an optical fiber interferometer which is operated with a laser diode at 830nm. We present current results obtained with porcine RPE explants in vitro and complete porcine eye globes ex vivo.},
       url = {http://dx.doi.org/10.1117/12.708521},
       type = {Conference Proceedings}
    }
    
  • Fritz, Andreas and Zegelin, Andrea and Ptaszynski, Lars and Birngruber, Reginald and Brinkmann, Ralf: Dynamics of laser induced micro bubble clusters on tissue phantoms. no. 7885, pp. 78850S-78850S-6,
    BibTeX
    @inproceedings{Fritz2011,
       author = {Fritz, Andreas and Zegelin, Andrea and Ptaszynski, Lars and Birngruber, Reginald and Brinkmann, Ralf},
       title = {Dynamics of laser induced micro bubble clusters on tissue phantoms},
       volume = {7885},
       pages = {78850S-78850S-6},
       note = {10.1117/12.875031},
       abstract = {Selective retina treatment (SRT) is a laser based method to treat retinal diseases associated with disorders of the retinal pigment epithelium (RPE) while preserving photoreceptors and choroid. Applying microsecond laser pulses to the 100- 200 strongly absorbing melanin granules inside the RPE cells induces transient micro bubbles which disrupt the cells. Aim of this work is to understand bubble dynamics in clusters with respect to the influence of the adjacent retina. Bubble dynamics were investigated in vitro on porcine RPE. An about 200 μm thick layer of agarose gel was applied to the RPE layer in order to simulate the mechanical properties of retina. Different laser pulse durations from 1 ns (532 nm, Nd:YAG) to 1.7 μs (527 nm, Nd:YLF) were used. The bubbles were investigated interferometrically (fiber interferometer @ 830 nm) and with fast flash photography (25 ns flash duration). Bubble lifetimes were measured. The results show that with retina phantoms the bubble formation threshold was reached at 2.5 times higher irradiation than without retina phantom for 1.7 μs laser pulses. The microbubbles generated with 1 ns laser pulses were almost not influenced by the agarose layer. Irradiation twofold over bubble formation threshold resulted in 3.5 times longer bubble lifetimes for μs and 2 times longer for ns pulse durations, respectively.},
       url = {http://dx.doi.org/10.1117/12.875031},
       type = {Conference Proceedings}
    }
    
  • Fritz, Andreas and Ptaszynski, Lars and Stoehr, Hardo and Brinkmann, Ralf: Dynamics and detection of laser induced microbubbles in the retinal pigment epithelium (RPE). no. 6632, pp. 66321C-66321C-11,
    BibTeX Link
    @inproceedings{Fritz2007,
       author = {Fritz, Andreas and Ptaszynski, Lars and Stoehr, Hardo and Brinkmann, Ralf},
       title = {Dynamics and detection of laser induced microbubbles in the retinal pigment epithelium (RPE)},
       volume = {6632},
       pages = {66321C-66321C-11},
       note = {10.1117/12.728344},
       abstract = {Selective Retina Treatment (SRT) is a new method to treat eye diseases associated with disorders of the RPE. Selective RPE cell damage is achieved by applying a train of 1.7 μs laser pulses at 527 nm. The treatment of retinal diseases as e.g. diabetic maculopathy (DMP), is currently investigated within clinical studies, however 200 ns pulse durations are under investigation. Transient micro bubbles in the retinal pigment epithelium (RPE) are expected to be the origin of cell damage due to irradiation with laser pulses shorter than 50 μs. The bubbles emerge at the strongly absorbing RPE melanosomes. Cell membrane disruption caused by the transient associated volume increase is expected to be the origin of the angiographically observed RPE leakage. We investigate micro bubble formation and dynamics in porcine RPE using pulse durations of 150 ns. A laser interferometry system at 830 nm with the aim of an online dosimetry control for SRT was developed. Bubble formation was detected interferometrically and by fast flash photography. A correlation to cell damage observed with a vitality stain is found. A bubble detection algorithm is presented.},
       url = {http://dx.doi.org/10.1117/12.728344},
       type = {Conference Proceedings}
    }
    
  • Fritz, Andreas and Ptaszynski, Lars and Stoehr, Hardo and Brinkmann, Ralf: Dynamics and detection of laser induced microbubbles in the retinal pigment epithelium (RPE). no. 6632, pp. 66321C-66321C-11,
    BibTeX
    @inproceedings{Fritz2007,
       author = {Fritz, Andreas and Ptaszynski, Lars and Stoehr, Hardo and Brinkmann, Ralf},
       title = {Dynamics and detection of laser induced microbubbles in the retinal pigment epithelium (RPE)},
       volume = {6632},
       pages = {66321C-66321C-11},
       note = {10.1117/12.728344},
       abstract = {Selective Retina Treatment (SRT) is a new method to treat eye diseases associated with disorders of the RPE. Selective RPE cell damage is achieved by applying a train of 1.7 μs laser pulses at 527 nm. The treatment of retinal diseases as e.g. diabetic maculopathy (DMP), is currently investigated within clinical studies, however 200 ns pulse durations are under investigation. Transient micro bubbles in the retinal pigment epithelium (RPE) are expected to be the origin of cell damage due to irradiation with laser pulses shorter than 50 μs. The bubbles emerge at the strongly absorbing RPE melanosomes. Cell membrane disruption caused by the transient associated volume increase is expected to be the origin of the angiographically observed RPE leakage. We investigate micro bubble formation and dynamics in porcine RPE using pulse durations of 150 ns. A laser interferometry system at 830 nm with the aim of an online dosimetry control for SRT was developed. Bubble formation was detected interferometrically and by fast flash photography. A correlation to cell damage observed with a vitality stain is found. A bubble detection algorithm is presented.},
       url = {http://dx.doi.org/10.1117/12.728344},
       type = {Conference Proceedings}
    }
    
  • Seifert, Eric and Roh, Young-Jung and Fritz, Andreas and Park, Young Gun and Kang, Seungbum and Theisen-Kunde, Dirk and Brinkmann, Ralf: Automatic irradiation control by an optical feedback technique for selective retina treatment (SRT) in a rabbit model. no. 8803, pp. 880303-880303-6,
    BibTeX Link
    @inproceedings{Seifert2013,
       author = {Seifert, Eric and Roh, Young-Jung and Fritz, Andreas and Park, Young Gun and Kang, Seungbum and Theisen-Kunde, Dirk and Brinkmann, Ralf},
       title = {Automatic irradiation control by an optical feedback technique for selective retina treatment (SRT) in a rabbit model},
       volume = {8803},
       pages = {880303-880303-6},
       note = {10.1117/12.2033560},
       abstract = {Selective Retina Therapy (SRT) targets the Retinal Pigment Epithelium (RPE) without effecting neighboring layers as the photoreceptors or the choroid. SRT related RPE defects are ophthalmoscopically invisible. Owing to this invisibility and the variation of the threshold radiant exposure for RPE damage the treating physician does not know whether the treatment was successful or not. Thus measurement techniques enabling a correct dosing are a demanded element in SRT devices. The acquired signal can be used for monitoring or automatic irradiation control. Existing monitoring techniques are based on the detection of micro-bubbles. These bubbles are the origin of RPE cell damage for pulse durations in the ns and μs time regime 5μs. The detection can be performed by optical or acoustical approaches. Monitoring based on an acoustical approach has already been used to study the beneficial effects of SRT on diabetic macula edema and central serous retinopathy. We have developed a first real time feedback technique able to detect micro-bubble induced characteristics in the backscattered laser light fast enough to cease the laser irradiation within a burst. Therefore the laser energy within a burst of at most 30 pulses is increased linearly with every pulse. The laser irradiation is ceased as soon as micro-bubbles are detected. With this automatic approach it was possible to observe invisible lesions, an intact photoreceptor layer and a reconstruction of the RPE within one week.},
       url = {http://dx.doi.org/10.1117/12.2033560},
       type = {Conference Proceedings}
    }