Dr. Dongyul Chai Profile

Dr. Dongyul Chai

at Sartorius BioAnalytical Instruments, Inc.

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Author

Publications (10)

Proceedings Article | 9 March 2021 Presentation

Stone ablation rates of a concept 100W pulse-modulated Holmium:YAG laser

Thomas Hasenberg, Bingyuan Yang, Ben Turney, Isha Parab, Jasmine Cancino, Sanwei Liu, Dongyul Chai, Aditi Ray, Tim Harrah, Hyun Kang

Proceedings Volume 11619, 1161907 (2021) https://doi.org/10.1117/12.2579016

KEYWORDS: Laser ablation, Prototyping, Fiber lasers, Surgery, Renal calculi, Pulsed laser operation, Laser vision correction, Laser therapeutics, Holmium

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Proceedings Article | 5 March 2021 Presentation + Paper

The optimal dusting mode for Ho:YAG laser lithotripsy

Jian Zhang, Dongyul Chai, Jason Xuan, Aditi Ray, Thomas Hasenberg, Timothy Harrah

Proceedings Volume 11619, 116190E (2021) https://doi.org/10.1117/12.2578984

KEYWORDS: Laser ablation, Laser lithotripsy, Laser systems engineering, Performance modeling, In vitro testing, High power lasers

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Proceedings Article | 5 March 2021 Presentation

Effect of holmium:YAG laser pulse modulation on lithotripsy particle size: a bench study

Sanwei Liu, Aditi Ray, James Zhang, Dongyul Chai, Jason Xuan, Steven Peng, Tim Harrah, Bingyuan Yang, Ben Turney, Hyun Kang, Thomas Hasenberg

Proceedings Volume 11619, 1161909 (2021) https://doi.org/10.1117/12.2578831

KEYWORDS: Particles, Pulsed laser operation, Modulation, Laser therapeutics, YAG lasers, Rutherfordium, Laser applications, Laser ablation, Holmium, Fiber lasers

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Proceedings Article | 19 February 2020 Presentation + Paper

In search of optimal settings for Ho:YAG laser-lithotripsy to maximize the ablation rate, while minimizing the retropulsion

Jian Zhang, Dongyul Chai, Jason Xuan, Aditi Ray, Thomas Hasenberg, Timothy Harrah

Proceedings Volume 11212, 1121204 (2020) https://doi.org/10.1117/12.2544546

KEYWORDS: Pulsed laser operation, Laser ablation, Laser therapeutics, Laser energy, Laser lithotripsy, Video, In vitro testing, Electronic test equipment, Diffractive optical elements

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Although laser lithotripsy is now the preferred treatment option for urolithiasis due to shorter operation time and a better stone-free rate [1], the optimal laser settings for URS (Ureteroscopic lithotripsy) to enable shorter operating times remain unclear. This study aims to identify optimal laser settings for Ho:YAG laser-lithotripsy to maximize the ablation rate while minimizing the retropulsion, as well as to improve the discharge of fragments via the urinary tract. The net result will be an increase in treatment success and patient satisfaction by ameliorating the stone-free rate.

In vitro investigations of Ho:YAG laser-induced stone ablation and retropulsion were performed with a bench top model first introduced by Sroka’s group [2]. A commercial Ho:YAG laser system (Lumenis VersaPulse PowerSuite 100W, Lumenis Ltd., Yokneam, Israel) was used as the laser pulse source, with pulse energy from 0.2 J up to 1.5 J and repetition rate from 5 to 40 Hz. A DOE with two replicate points and two lack-of-fit points was performed on artificial BEGO stones of sample size 14 under reproducible experimental conditions (fiber size: 365 μm, S-LLF365 SureFlex Fiber, Boston Scientific Corporation, San Jose, CA, USA). The best fit to the experimental data was analyzed utilizing the design of experiment software, which can produce the numerical formulas for the response surfaces of ablation rate and retropulsion in terms of laser pulse parameters [3].

The coded numerical formulas for the response surfaces of ablation speed and retropulsion velocity are generated. The coded equation is useful for identifying the relative impact of the factors by comparing their coefficients. Upon examination of the laser ablation of stone phantoms (BEGO), the laser pulse energy is 1.4 times the impact of the frequency, and laser pulse peak power’s impact is the same as the frequency; while for retropulsion, the laser pulse energy is 5.8 times as the impact of the frequency, and laser pulse peak power’s impact is 13 times as the frequency; A series of laser settings for relatively efficient laser lithotripsy were identified in terms of laser pulse energy and peak power.

The laser pulse energy or peak power in reference to frequency has a higher impact coefficient to stone retropulsion as compared to stone ablation in Ho:YAG laser-lithotripsy. The most effective way to reduce stone retropulsion during laser lithotripsy is to reduce the laser pulse peak power (which has the highest impact coefficient in the coded response equation).

Proceedings Article | 4 March 2019 Presentation

The study of Ho: YAG laser ablation thresholds of calculus phantom in terms of peak power density (Conference Presentation)

Dongyul Chai, Jian Zhang, Nazia Podana, Rongwei Xuan, Thomas Hasenberg, Timothy Harrah

Proceedings Volume 10852, 108520D (2019) https://doi.org/10.1117/12.2510122

KEYWORDS: Laser ablation, YAG lasers, Holmium, Laser damage threshold, Calculus, Pulsed laser operation, Laser lithotripsy, Fiber lasers, Laser energy, Photodiodes

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SPIE Journal Paper | 20 March 2013 Open Access

Nonlinear optical collagen cross-linking and mechanical stiffening: a possible photodynamic therapeutic approach to treating corneal ectasia

Dongyul Chai, Tibor Juhasz, Donald Brown, James Jester

JBO, Vol. 18, Issue 03, 038003, (March 2013) https://doi.org/10.1117/12.10.1117/1.JBO.18.3.038003

KEYWORDS: Collagen, Nonlinear optics, Cornea, Femtosecond phenomena, Optical fibers, Photodynamic therapy, Luminescence, Laser therapeutics, Tissues, Second-harmonic generation

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Proceedings Article | 25 February 2010 Paper

High resolution macroscopy (HRMac) of the eye using nonlinear optical imaging

Moritz Winkler, Bryan Jester, Chyong Nien-Shy, Dongyul Chai, Donald Brown, James Jester

Proceedings Volume 7589, 758906 (2010) https://doi.org/10.1117/12.847897

KEYWORDS: Cornea, Tissues, Image resolution, Collagen, Nonlinear optics, Optic nerve, Second-harmonic generation, Tissue optics, 3D image processing, Eye

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Proceedings Article | 26 March 2007 Paper

Investigation and visualization of scleral channels created with femtosecond laser in enucleated human eyes using 3D optical coherence tomography images

Gautam Chaudhary, Bin Rao, Dongyul Chai, Zhongping Chen, Tibor Juhasz

Proceedings Volume 6426, 64260B (2007) https://doi.org/10.1117/12.701297

KEYWORDS: Optical coherence tomography, Femtosecond phenomena, 3D image processing, Digital filtering, Image filtering, Visualization, Tissues, Eye, Speckle, Edge detection

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We used optical coherence tomography (OCT) for non-invasive imaging of the anterior segment of the eye for investigating partial-thickness scleral channels created with a femtosecond laser. Glaucoma is associated with elevated intraocular pressure (IOP) due to reduced outflow facility in the eye. A partial-thickness aqueous humor (AH) drainage channel in the sclera was created with 1.7-&mgr;m wavelength femtosecond laser pulses to reduce IOP by increasing the outflow facility, as a solution to retard the progression of glaucoma. It is hypothesized that the precise dimensions and predetermined location of the channel would provide a controlled increase of the outflow rate resulting in IOP reduction. Therefore, it is significant to create the channel at the exact location with predefined dimensions. The aim of this research has two aspects. First, as the drainage channel is subsurface, it is a challenging task to determine its precise location, shape and dimensions, and it becomes very important to investigate the channel attributes after the laser treatment without disturbing the internal anterior structures. Second, to provide a non-invasive, image-based verification that extremely accurate and non-scarring AH drainage channel can be created with femtosecond laser. Partial-thickness scleral channels created in five human cadaver eyes were investigated non-invasively with a 1310-nm time-domain OCT imaging system. Three-dimensional (3D) OCT image stacks of the triangular cornea-sclera junction, also known as anterior chamber angle, were acquired for image-based analysis and visualization. The volumetric cutting-plane approach allowed reconstruction of images at any cross-sectional position in the entire 3D volume of tissue, making it a valuable tool for exploring and evaluating the location, shape and dimension of the channel from all directions. As a two-dimensional image-based methodology, an image-processing pipeline was implemented to enhance the channel features to augment the analysis. In conclusion, we successfully demonstrate that our image-based visualization tool is appropriate for effective investigation and evaluation of femtosecond laser-created, partial-thickness aqueous humor drainage channels in the sclera.

Proceedings Article | 22 February 2007 Paper

Imaging subsurface photodisruption in human sclera with FD-OCT

Bin Rao, Jianping Su, Dongyul Chai, Gautam Chaudhary, Zhongping Chen, Tibor Juhasz

Proceedings Volume 6429, 642910 (2007) https://doi.org/10.1117/12.704857

KEYWORDS: 3D image processing, Sclera, Optical coherence tomography, Femtosecond phenomena, Imaging systems, Laser ablation, Laser tissue interaction, Laser systems engineering, 3D vision, Natural surfaces

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Proceedings Article | 6 February 2007 Paper

Aqueous humor outflow effects of partial thickness channel created by a femtosecond laser in ex-vivo human eyes

Dongyul Chai, Gautam Chaudhary, Ron Kurtz, Tibor Juhasz

Proceedings Volume 6435, 64350O (2007) https://doi.org/10.1117/12.701416

KEYWORDS: Eye, Laser therapeutics, Femtosecond phenomena, Sclera, Microscopes, Control systems, Raster graphics, Resistance, Pulsed laser operation, Laser systems engineering

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