Dr. Héctor A. García Profile

Dr. Héctor A. García

at UNICEM

SPIE Involvement:

Author

Publications (5)

SPIE Journal Paper | 28 February 2024 Open Access

Retrieval of chromophore concentration changes in a digital human head model using analytical mean partial pathlengths of photons

Demián Vera, Héctor García, Nicolás Carbone, María Victoria Waks-Serra, Daniela Iriarte, Juan Pomarico

JBO, Vol. 29, Issue 02, 025004, (February 2024) https://doi.org/10.1117/12.10.1117/1.JBO.29.2.025004

KEYWORDS: Chromophores, Analytic models, Head, Absorption, Simulations, Sensors, Photons, Tissues, Brain, Reconstruction algorithms

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SignificanceContinuous-wave functional near-infrared spectroscopy has proved to be a valuable tool for assessing hemodynamic activity in the human brain in a non-invasively and inexpensive way. However, most of the current processing/analysis methods assume the head is a homogeneous medium, and hence do not appropriately correct for the signal coming from the scalp. This effect can be reduced by considering light propagation in a layered model of the human head, being the Monte Carlo (MC) simulations the gold standard to this end. However, this implies large computation times and demanding hardware capabilities.AimIn this work, we study the feasibility of replacing the homogeneous model and the MC simulations by means of analytical multilayered models, combining in this way, the speed and simplicity of implementation of the former with the robustness and accuracy of the latter.ApproachOxy- and deoxyhemoglobin (HbO and HbR, respectively) concentration changes were proposed in two different layers of a magnetic resonance imaging (MRI)-based meshed model of the human head, and then these changes were retrieved by means of (i) a typical homogeneous reconstruction and (ii) a theoretical layered reconstruction.ResultsResults suggest that the use of analytical models of light propagation in layered models outperforms the results obtained using traditional homogeneous reconstruction algorithms, providing much more accurate results for both, the extra- and the cerebral tissues. We also compare the analytical layered reconstruction with MC-based reconstructions, achieving similar degrees of accuracy, especially in the gray matter layer, but much faster (between 4 and 5 orders of magnitude).ConclusionsWe have successfully developed, implemented, and validated a method for retrieving chromophore concentration changes in the human brain, combining the simplicity and speed of the traditional homogeneous reconstruction algorithms with robustness and accuracy much more similar to those provided by MC simulations.

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Proceedings Article | 21 August 2023 Paper

Analytical photon measurement density functions in flat and spherical layered media

Demián Vera, Héctor García, Guido Baez, María Waks-Serra, Nicolás Carbone, Daniela Iriarte, Juan Pomarico

Proceedings Volume 12628, 126281K (2023) https://doi.org/10.1117/12.2667099

KEYWORDS: Spherical lenses, Monte Carlo methods, Tissue optics, Brain tissue, Brain, Windows, Simulations, Refractive index, Photon transport, Optical sensing

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Proceedings Article | 21 August 2023 Paper

Theoretical computation of photon mean partial pathlengths in multilayered turbid media

Demián Vera, Héctor García, Nicolás Carbone, María Waks-Serra, Daniela Iriarte, Juan Pomarico

Proceedings Volume 12628, 126281X (2023) https://doi.org/10.1117/12.2670453

KEYWORDS: Turbidity, Simulations, Optical properties, Optical computing, Multilayers, Analytic models, Source detector separation, Photodetectors, Monte Carlo methods, Head

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