1. Ryerson University

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    1. Mentioned In 91 Articles

    2. Optical coherence tomography for dynamic axial correction of an optical end-effector for robot-guided surgical laser ablation

      Optical coherence tomography for dynamic axial correction of an optical end-effector for robot-guided surgical laser ablation
      Robot-guided laser ablation for surgical applications potentially offers many advantages compared to by-hand mechanical tissue cutting. However, given that tissue can be rough and/or uneven, ablation quality can be compromised if the beam waist deviates significantly from the target tissue surface. Therefore, we present a method that uses optical coherence tomography (OCT) for dynamic refocusing of robot-guided surgical laser ablation. A 7-DOF robotic manipulator with an OCT-equipped optical payload ...
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    3. 2D MEMS-based high-speed beam-shifting technique for speckle noise reduction and flow rate measurement in optical coherence tomography

      2D MEMS-based high-speed beam-shifting technique for speckle noise reduction and flow rate measurement in optical coherence tomography
      In this manuscript, a two-dimensional (2D) micro-electro-mechanical system (MEMS)-based, high-speed beam-shifting spectral domain optical coherence tomography (MHB-SDOCT) is proposed for speckle noise reduction and absolute flow rate measurement. By combining a zigzag scanning protocol, the frame rates of 45.2 Hz for speckle reduction and 25.6 Hz for flow rate measurement are achieved for in-vivo tissue imaging. Phantom experimental results have shown that by setting the incident beam ...
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    4. Dynamic light scattering optical coherence tomography to probe motion of subcellular scatterers

      Dynamic light scattering optical coherence tomography to probe motion of subcellular scatterers
      Optical coherence tomography (OCT) is used to provide anatomical information of biological systems but can also provide functional information by characterizing the motion of intracellular structures. Dynamic light scattering OCT was performed on intact, control MCF-7 breast cancer cells and cells either treated with paclitaxel to induce apoptosis or deprived of nutrients to induce oncosis. Autocorrelations (ACs) of the temporal fluctuations of OCT intensity signals demonstrate a significant decrease in ...
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    5. Beam-shifting technique for speckle reduction and flow rate measurement in optical coherence tomography

      Beam-shifting technique for speckle reduction and flow rate measurement in optical coherence tomography
      In this Letter, we propose a beam-shifting optical coherence tomography scheme for speckle reduction and blood flow rate calculation, where variations of the speckle pattern and Doppler angle were generated by parallel shifting of the sample beam incident on the objective lens. The resultant optical coherent tomography images could then be averaged for speckle noise reduction and simultaneously analyzed for flow rate measurement. The performance of the proposed technique was ...
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    6. Buffer-averaging super-continuum source based spectral domain optical coherence tomography for high speed imaging

      Buffer-averaging super-continuum source based spectral domain optical coherence tomography for high speed imaging
      In super-continuum (SC) source based spectral domain optical coherence tomography (SC-SDOCT), the stability of the power spectral density (PSD) has a significant impact on OCT system sensitivity and image signal to noise ratio (SNR). High speed imaging decreases the camera's exposure time, thus each A-scan contained fewer laser pulse excited SC wideband emissions, resulting in a decrease of SNR. In this manuscript, we present a buffer-averaging SC-SDOCT (BASC-SDOCT) to ...
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    7. Carotid artery stenting with optical coherence tomography

      Carotid artery stenting with optical coherence tomography
      A 61-year-old man underwent a left cervical internal carotid artery stenting following a recent ischemic stroke. Postoperative angiography was satisfactory and did not reveal any in-stent filling defect ( figure 1A ). Optical coherence tomography (OCT) probe was used to visualize the endoluminal area following stenting. OCT confirmed optimum placement of the stent and reveled a small plaque protrusion from the stent struts following deployment ( figure 1B ).
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    8. Gabor optical coherence tomographic angiography (GOCTA) (Part I): human retinal imaging in vivo

      Gabor optical coherence tomographic angiography (GOCTA) (Part I): human retinal imaging in vivo
      Recently, parallel high A-line speed and wide field imaging for optical coherence tomography angiography (OCTA) has become more prevalent, resulting in a dramatic increase of data quantity which poses a challenge for real time imaging even for GPU in data processing. In this manuscript, we propose a new OCTA processing technique, Gabor optical coherence tomographic angiography (GOCTA), for label-free human retinal angiography imaging. In spectral domain optical coherence tomography (SDOCT ...
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    9. High speed, wide velocity dynamic range Doppler optical coherence tomography (Part V): Optimal utilization of multi-beam scanning for Doppler and speckle variance microvascular imaging

      High speed, wide velocity dynamic range Doppler optical coherence tomography (Part V): Optimal utilization of multi-beam scanning for Doppler and speckle variance microvascular imaging
      In this paper, a multi-beam scanning technique is proposed to optimize the microvascular images of human skin obtained with Doppler effect based methods and speckle variance processing. Flow phantom experiments were performed to investigate the suitability for combining multi-beam data to achieve enhanced microvascular imaging. To our surprise, the highly variable spot sizes (ranging from 13 to 77 m) encountered in high numerical aperture multi-beam OCT system imaging the same ...
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    10. Intraoperative optical coherence tomography of the cerebral cortex using a 7 degree-of freedom robotic arm

      Intraoperative optical coherence tomography of the cerebral cortex using a 7 degree-of freedom robotic arm
      Optical Coherence Tomography (OCT) provides a high-resolution imaging technique with limited depth penetration. The current use of OCT is limited to relatively small areas of tissue for anatomical structure diagnosis or minimally invasive guided surgery. In this study, we propose to image a large area of the surface of the cerebral cortex. This experiment aims to evaluate the potential difficulties encountered when applying OCT imaging to large and irregular surface ...
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    11. Graphics processor unit acceleration enables realtime endovascular Doppler optical coherence tomography imaging

      Graphics processor unit acceleration enables realtime endovascular Doppler optical coherence tomography imaging
      Endovascular Optical Coherence Tomography (OCT) has previously been used in both bench-top and clinical environments to produce vascular images, and can be helpful in characterizing, among other pathologies, plaque build-up and impedances to normal blood ow. The raw data produced can also be processed to yield high- resolution blood velocity information, but this computation is expensive and has previously only been available a posteriori using post-processing software. Real-time Doppler OCT ...
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    12. Multi-beam optical coherence tomography for microvascular imaging of human skin in vivo

      Multi-beam optical coherence tomography for microvascular imaging of human skin in vivo
      In this paper, a multi-beam optical coherence tomography (OCT) was used to reconstruct the microvascular image of human skin in vivo with phase resolved Doppler OCT (PRDOCT), phase resolved Doppler variance (PRDV) and speckle variance OCT (svOCT), in which the blood flow image was calculated by averaging the four blood flow images obtained by the four beams. In PRDOCT method, it is difficult to detect the blood flow perpendicular to ...
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    13. Differential standard deviation of log-scale intensity based optical coherence tomography angiography

      Differential standard deviation of log-scale intensity based optical coherence tomography angiography
      In this paper, a differential standard deviation of log-scale intensity (DSDLI) based optical coherence tomography angiography (OCTA) is presented for calculating microvascular images of human skin. The DSDLI algorithm calculates the variance in difference images of two consecutive log-scale intensity based structural images from the same position along depth direction to contrast blood flow. The en face microvascular images were then generated by calculating the standard deviation of the differential ...
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    14. Microvascular contrast enhancement in optical coherence tomography using microbubbles

      Microvascular contrast enhancement in optical coherence tomography using microbubbles
      Gas microbubbles (MBs) are investigated as intravascular optical coherence tomography (OCT) contrast agents. Agar + intralipid scattering tissue phantoms with two embedded microtubes were fabricated to model vascular blood flow. One was filled with human blood, and the other with a mixture of human blood + MB. Swept-source structural and speckle variance (sv) OCT images, as well as speckle decorrelation times, were evaluated under both no-flow and varying flow conditions. Faster decorrelation ...
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    15. Measuring intracellular motion in cancer cell using optical coherence tomography

      Measuring intracellular motion in cancer cell using optical coherence tomography
      In this study, we demonstrate that OCT speckle decorrelation techniques can be used to probe intracellular motion in cancer cells. Spheroids and cell pellets were used as a model to probe intracellular motion. ZnCl 2 was used to inhibit mitochondrial motion within the cells. The results reveal the changes in intracellular motion during the spheroid growth phase. Moreover, to modify the motion of mitochondria, cell pellet were exposed to ZnCl ...
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    16. Blood flow contrast enhancement in optical coherence tomography using microbubbles: a phantom study

      Blood flow contrast enhancement in optical coherence tomography using microbubbles: a phantom study
      In this study gas microbubbles are investigated as intravascular OCT contrast agents. Agar+Intralipid scattering tissue-like phantoms with two embedded microtubes were fabricated to model vascular blood flow. One was filled with human blood, and the other with a mixture of human blood and microbubbles. Swept-source structural and speckle variance OCT images, as well as speckle decorrelation times, were evaluated under both stationary and flow conditions. Faster decorrelation times and ...
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    17. 1-15 of 91 1 2 3 4 5 6 »
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  2. About Ryerson University

    Ryerson University

    Ryerson University is Canada’s leader in innovative, career-focused education and a university clearly on the move. It is a distinctly urban university with a mission to serve societal need, and a long-standing commitment to engaging its community. Guided by a bold new Academic Plan, an ambitious research agenda, and a recently-completed Master Plan to revitalize the campus and surrounding neighbourhood, Ryerson is now the most applied-to university in Ontario relative to available spaces, and its reputation with business and community leaders continues to rise. In just a few years since the introduction of its first master's program, Ryerson has grown to host 2,000 graduate students in 34 programs, including nine at the doctoral level. The University now ranks third in Canada - and first in Ontario - in terms of research growth. And Ryerson is reshaping the downtown core of Toronto with two new buildings: a Photography Gallery and Research Centre in the heart of campus, and a Student Learning Centre on the site of the iconic Sam the Record Man property on Yonge Street, in the heart of the city. Since 1948, Ryerson has built its reputation on the strength of its academic curriculum, and offers close to 100 PhD, master's, and undergraduate programs, with a total enrolment of 25,000 and more than 65,000 registrations annually in The G. Raymond Chang School of Continuing Education.