Dr. Lüder A. Alexander Kahrs Profile

Dr. Lüder A. Alexander Kahrs

Assistant Professor at Univ of Toronto Mississauga

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Publications (18)

Proceedings Article | 29 March 2024 Presentation + Paper

Presentation + Paper

Enhancing MR-guided laser interstitial thermal therapy planning using U-Net: a data-driven approach for predicting MR thermometry images

Saba Sadatamin, Sara Ketabi, Elise Donszelmann-Lund, Saba Abtahi, Yuri Chaban, Steven Robbins, Richard Tyc, Farzad Khalvati, Adam Waspe, Lueder Kahrs, James Drake

Proceedings Volume 12928, 129281J (2024) https://doi.org/10.1117/12.3006041

KEYWORDS: Magnetic resonance imaging, Thermometry, Anatomy, Laser therapeutics, Education and training, Histograms, Data modeling, Brain, Performance modeling, Epilepsy

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Proceedings Article | 29 March 2024 Poster + Paper

Poster + Paper

An assistive photo capture system for pre- and post-operative analysis of facial reconstructive surgeries

Wenzhangzhi Guo, Yanlin Huang, Joel Davies, Vito Forte, Eitan Grinspun, Lueder Kahrs

Proceedings Volume 12928, 129281R (2024) https://doi.org/10.1117/12.3005700

KEYWORDS: Head, Cameras, Surgery, Facial reconstruction surgery, Image processing, Image registration, Wound healing, Visualization

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SPIE Journal Paper | 19 February 2021 Open Access

Open Access

Concept description and accuracy evaluation of a moldable surgical targeting system

Thomas Rau, Sina Witte, Lea Uhlenbusch, Lüder A. Kahrs, Thomas Lenarz, Omid Majdani

JMI, Vol. 8, Issue 01, 015003, (February 2021) https://doi.org/10.1117/12.10.1117/1.JMI.8.1.015003

KEYWORDS: Bone, Cements, Skull, Ear, Surgery, Optical spheres, Image-guided intervention, Image registration, Solid modeling, Optical alignment

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Proceedings Article | 19 July 2019 Paper

Paper

Semantic denoising autoencoders for retinal optical coherence tomography

Max-Heinrich Laves, Sontje Ihler, Lüder Alexander Kahrs, Tobias Ortmaier

Proceedings Volume 11078, 1107818 (2019) https://doi.org/10.1117/12.2526936

KEYWORDS: Denoising, Optical coherence tomography, Signal to noise ratio, Image classification, Speckle, Medical imaging, Wavelets, Medical diagnostics, Ophthalmology, Classification systems

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Proceedings Article | 8 March 2019 Presentation + Paper

Presentation + Paper

Deep-learning-based 2.5D flow field estimation for maximum intensity projections of 4D optical coherence tomography

Max-Heinrich Laves, Sontje Ihler, Lüder Kahrs, Tobias Ortmaier

Proceedings Volume 10951, 109510R (2019) https://doi.org/10.1117/12.2512952

KEYWORDS: Optical coherence tomography, Bone, Laser ablation, Optical flow, Convolutional neural networks, Laser safety

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Proceedings Article | 8 March 2019 Paper

Paper

Endoscopic guidance system for stimulation of the laryngeal adductor reflex by droplet impact

Jacob Friedemann Fast, Adrian Karl Rüppel, Caroline Bärhold, Michael Jungheim, Tobias Ortmaier, Martin Ptok, Lüder Alexander Kahrs

Proceedings Volume 10951, 109510M (2019) https://doi.org/10.1117/12.2512852

KEYWORDS: Endoscopy, Endoscopes, Visualization, Image visualization, Imaging systems, High speed cameras, Algorithm development, Computer aided diagnosis and therapy, Medical diagnostic instruments, Non-invasive medical diagnostics, Optical diagnostics, Stereoscopy

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Proceedings Article | 28 May 2018 Paper

Paper

User evaluation study on illumination requirements to design an augmented reality projector for open liver surgery

Shivaraman Ilango, Marvin Knöchelmann, Lüder Alexander Kahrs, Alexander Wolf, Tobias Ortmaier, Roland Lachmayer

Proceedings Volume 10693, 106930R (2018) https://doi.org/10.1117/12.2309667

KEYWORDS: Projection systems, Surgery, Visibility, Liver, Augmented reality, Visualization, Image resolution, Statistical analysis, Tissues

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Proceedings Article | 3 March 2017 Presentation + Paper

Presentation + Paper

Feature tracking for automated volume of interest stabilization on 4D-OCT images

Max-Heinrich Laves, Andreas Schoob, Lüder Kahrs, Tom Pfeiffer, Robert Huber, Tobias Ortmaier

Proceedings Volume 10135, 101350W (2017) https://doi.org/10.1117/12.2255090

KEYWORDS: Optical coherence tomography, Medical imaging, Optical tracking, Image processing, Automatic tracking, Image analysis, Tissues, 3D image processing, Visualization, Detection and tracking algorithms, Image acquisition, Sensors

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Proceedings Article | 3 March 2017 Presentation + Paper

Presentation + Paper

Panorama imaging for image-to-physical registration of narrow drill holes inside spongy bones

Jan Bergmeier, Jacob Friedemann Fast, Tobias Ortmaier, Lüder Alexander Kahrs

Proceedings Volume 10135, 1013507 (2017) https://doi.org/10.1117/12.2254417

KEYWORDS: Imaging systems, Mirrors, Optics manufacturing, Image processing, Image registration, Panoramic photography, Endoscopy, Bone, Endoscopes, Computed tomography, Cones, Data acquisition, Software development, Image processing software

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Image-to-physical registration based on volumetric data like computed tomography on the one side and intraoperative endoscopic images on the other side is an important method for various surgical applications. In this contribution, we present methods to generate panoramic views from endoscopic recordings for image-to-physical registration of narrow drill holes inside spongy bone. One core application is the registration of drill poses inside the mastoid during minimally invasive cochlear implantations. Besides the development of image processing software for registration, investigations are performed on a miniaturized optical system, achieving 360° radial imaging with one shot by extending a conventional, small, rigid, rod lens endoscope. A reflective cone geometry is used to deflect radially incoming light rays into the endoscope optics. Therefore, a cone mirror is mounted in front of a conventional 0° endoscope. Furthermore, panoramic images of inner drill hole surfaces in artificial bone material are created. Prior to drilling, cone beam computed tomography data is acquired from this artificial bone and simulated endoscopic views are generated from this data. A qualitative and quantitative image comparison of resulting views in terms of image-to-image registration is performed. First results show that downsizing of panoramic optics to a diameter of 3mm is possible. Conventional rigid rod lens endoscopes can be extended to produce suitable panoramic one-shot image data. Using unrolling and stitching methods, images of the inner drill hole surface similar to computed tomography image data of the same surface were created. Registration is performed on ten perturbations of the search space and results in target registration errors of (0:487 ± 0:438)mm at the entry point and (0:957 ± 0:948)mm at the exit as well as an angular error of (1:763 ± 1:536)°. The results show suitability of this image data for image-to-image registration. Analysis of the error components in different directions reveals a strong influence of the pattern structure, meaning higher diversity results into smaller errors.

Proceedings Article | 7 March 2016 Paper

Paper

Endoluminal non-contact soft tissue ablation using fiber-based Er:YAG laser delivery

Dennis Kundrat, Alexander Fuchs, Andreas Schoob, Lüder Kahrs, Tobias Ortmaier

Proceedings Volume 9702, 97020E (2016) https://doi.org/10.1117/12.2211796

KEYWORDS: Laser tissue interaction, Laser ablation, Fiber lasers, Er:YAG lasers, Laser therapeutics, Optical fibers, Laser applications, Laser vision correction, Laser optics, Absorption, Tissues, Surgery, Laser processing, Tissue optics, Lenses

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Proceedings Article | 15 July 2015 Paper

Paper

Fast and automatic depth control of iterative bone ablation based on optical coherence tomography data

Alexander Fuchs, Steffen Pengel, Jan Bergmeier, Lüder Kahrs, Tobias Ortmaier

Proceedings Volume 9542, 95420P (2015) https://doi.org/10.1117/12.2183695

KEYWORDS: Laser ablation, Optical coherence tomography, Bone, Er:YAG lasers, Laser tissue interaction, Tissues, Natural surfaces, Laser cutting, Image processing, Detection and tracking algorithms

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Proceedings Article | 20 March 2015 Paper

Paper

Cochlear shape description and analyzing via medial models

Johannes Gaa, Lüder Kahrs, Samuel Müller, Omid Majdani, Tobias Ortmaier

Proceedings Volume 9413, 941345 (2015) https://doi.org/10.1117/12.2082033

KEYWORDS: Chemical species, Data modeling, Image segmentation, Shape analysis, Computed tomography, Ear, Statistical analysis, Statistical modeling, 3D modeling, Principal component analysis

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Proceedings Article | 18 March 2015 Paper

Paper

Methods for intraoperative, sterile pose-setting of patient-specific microstereotactic frames

Benjamin Vollmann, Samuel Müller, Dennis Kundrat, Tobias Ortmaier, Lüder Kahrs

Proceedings Volume 9415, 94150M (2015) https://doi.org/10.1117/12.2082066

KEYWORDS: Cements, Bone, Computer aided design, Rapid manufacturing, Silicon, Mechatronics, Manufacturing, Brain stimulation, Skull, Fluoroscopy

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Proceedings Article | 18 March 2015 Paper

Paper

Comparison of tablet-based strategies for incision planning in laser microsurgery

Andreas Schoob, Stefan Lekon, Dennis Kundrat, Lüder Kahrs, Leonardo Mattos, Tobias Ortmaier

Proceedings Volume 9415, 94150J (2015) https://doi.org/10.1117/12.2081032

KEYWORDS: Visualization, Tablets, Laser ablation, Laser microsurgery, Laser therapeutics, Cameras, Laser tissue interaction, Natural surfaces, Stereoscopic cameras, Human-machine interfaces

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Proceedings Article | 18 March 2015 Paper

Paper

Methods for a fusion of optical coherence tomography and stereo camera image data

Jan Bergmeier, Dennis Kundrat, Andreas Schoob, Lüder Kahrs, Tobias Ortmaier

Proceedings Volume 9415, 94151C (2015) https://doi.org/10.1117/12.2082511

KEYWORDS: Optical coherence tomography, Stereoscopic cameras, Image segmentation, Cameras, Clouds, Image registration, Image fusion, Visualization, Augmented reality, 3D image processing

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Proceedings Article | 17 February 2012 Paper

Paper

Bent rigid endoscopes: a challenge for accurate distortion correction and 3D reconstruction

Lueder Kahrs, Robert Labadie

Proceedings Volume 8316, 83162E (2012) https://doi.org/10.1117/12.911762

KEYWORDS: Endoscopes, Distortion, Calibration, Endoscopy, 3D modeling, Cameras, Surgery, Tissues, Medical imaging, Failure analysis

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Proceedings Article | 17 February 2012 Paper

Paper

Measurement of distances between anatomical structures using a translating stage with mounted endoscope

Lueder Kahrs, Gregoire Blachon, Ramya Balachandran, J. Michael Fitzpatrick, Robert Labadie

Proceedings Volume 8316, 83160X (2012) https://doi.org/10.1117/12.911464

KEYWORDS: Endoscopes, Distance measurement, Cameras, Endoscopy, Surgery, 3D modeling, 3D metrology, Bone, Nerve, 3D image processing

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Proceedings Article | 17 March 2008 Paper

Paper

Visual servoing of a laser ablation based cochleostomy

Lüder Kahrs, Jörg Raczkowsky, Martin Werner, Felix Knapp, Markus Mehrwald, Peter Hering, Jörg Schipper, Thomas Klenzner, Heinz Wörn

Proceedings Volume 6918, 69182C (2008) https://doi.org/10.1117/12.770863

KEYWORDS: Laser ablation, Bone, Visualization, Cameras, Image processing, Image segmentation, Pulsed laser operation, Ear, Surgery, Process control

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Showing 5 of 18 publications

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