Dr. Tae-Hoon Bok Profile

Dr. Tae-Hoon Bok

Postdoctoral Fellow at Toronto Metropolitan Univ

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Publications (6)

Proceedings Article | 17 March 2023 Paper

The study of aerosolized droplets with nanometer absorbing structures using a contactless photoacoustic technique and the finite-difference time-domain method

Krishnan Sathiyamoorthy, Eric Strohm, Omar Nusrat, Taehoon Bok, Ahmet Karataş, Michael Kolios

Proceedings Volume 12397, 1239708 (2023) https://doi.org/10.1117/12.2650522

KEYWORDS: Gold, Gold nanoparticles, Particles, Finite-difference time-domain method, Photoacoustic spectroscopy, Light absorption, Viruses, Ultraviolet radiation, Surface plasmons, Transducers

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SPIE Journal Paper | 23 March 2021 Open Access

In vivo photoacoustic assessment of the oxygen saturation changes in the human radial artery: a preliminary study associated with age

Taehoon Bok, Eno Hysi, Michael Kolios

JBO, Vol. 26, Issue 03, 036006, (March 2021) https://doi.org/10.1117/12.10.1117/1.JBO.26.3.036006

KEYWORDS: Protactinium, Oxygen, Blood, In vivo imaging, Arteries, Blood circulation, Photoacoustic spectroscopy, Hemodynamics, In vitro testing, Imaging systems

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Proceedings Article | 4 March 2019 Presentation

Speckle formation in acoustic-resolution photoacoustic imaging (Conference Presentation)

Eno Hysi, Muhannad Fadhel, Michael Moore, Tae-Hoon Bok, Jason Zalev, Eric Strohm, Michael Kolios

Proceedings Volume 10878, 108781H (2019) https://doi.org/10.1117/12.2508837

KEYWORDS: Speckle, Photoacoustic imaging, Photoacoustic spectroscopy, Arteries, Imaging systems, Numerical simulations, Spherical lenses, Optical simulations, Chemical elements, Signal generators

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Proceedings Article | 3 March 2017 Paper

Quantitative photoacoustic assessment of red blood cell aggregation under pulsatile blood flow: experimental and theoretical approaches

Tae-Hoon Bok, Eno Hysi, Michael Kolios

Proceedings Volume 10064, 100645F (2017) https://doi.org/10.1117/12.2250221

KEYWORDS: Monte Carlo methods, Spectroscopy, Mass attenuation coefficient, Absorption, Imaging systems, Sensors, Blood, Photoacoustic spectroscopy, Blood circulation, Hemodynamics

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Proceedings Article | 15 March 2016 Presentation + Paper

Effect of optical wavelength on photoacoustic investigations of pulsatile blood flow

Tae-Hoon Bok, Eno Hysi, Michael Kolios

Proceedings Volume 9708, 97081M (2016) https://doi.org/10.1117/12.2212108

KEYWORDS: Blood, Photoacoustic spectroscopy, Oxygen, Blood circulation, Spherical lenses, Beam propagation method, Physiology, Spectroscopy, Picosecond phenomena, Absorption, Biomedical optics, Analytical research

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This paper attempts to experimentally and analytically quantify the aggregation-induced changes in the photoacoustic amplitude (PAA) by simultaneously examining the effect of red blood cell (RBC) aggregate size and optical illumination wavelength. In experiments, the pulsatile flow of human whole blood at 60 bpm was imaged using the VevoLAZR system equipped with a 40-MHz-linear-array probe. The samples were illuminated every 10 nm from 700 to 900 nm. For the analytical model, the PAA from both a collection of randomly distributed RBCs of 5, 10, 15, 20, 25, and 30 cells and a single absorber as a spherical aggregate of RBCs formed by the corresponding number of RBCs. The oxygen saturation (sO2) was measured as 74% and 80% for the non-aggregated RBCs and the RBC aggregation. These values were assigned to the analytical RBC aggregates containing between 5 and 30 cells. The normalized PAA (nPAA) for the experimental results was compared to that generated by the theoretical calculations. At a given wavelength, the analytical nPAA for the collection of RBCs were identical for all numbers of RBCs, but that for the RBC aggregate increased with the number of RBCs forming the aggregate due to the increase in the effective photoacoustic absorber size. The experimental as well as analytical nPAA for both RBC aggregation and non-aggregation increased with the wavelength at a given absorber size. This was due to the fact that the PAA is mainly determined by the optical absorption coefficient (μa) which increases due to the relationship between εHbO and wavelength. In addition, the difference of PAA between RBC aggregation and nonaggregation also increased with the wavelength due to the increase in the μa induced by the hypothesized enhanced sO2 resulting from the increased size of RBC aggregates. These results can be used as a means of estimating the oxygen loading and unloading during blood flow. This investigation elucidates the quantitative relationship between the RBC aggregate size and the optical illumination wavelength for probing the physiology of flowing blood.

Proceedings Article | 11 March 2015 Paper

High-frequency photoacoustic imaging of erythrocyte aggregation and oxygen saturation: probing hemodynamic relations under pulsatile blood flow

Tae-Hoon Bok, Eno Hysi, Michael Kolios

Proceedings Volume 9323, 93231Q (2015) https://doi.org/10.1117/12.2076650

KEYWORDS: Blood circulation, Blood, Oxygen, Photoacoustic imaging, Imaging systems, Hemodynamics, Velocity measurements, Beam propagation method, Photoacoustic spectroscopy, Ultrasonography

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