Dr. Alexander P. Dumont Profile

Dr. Alexander P. Dumont

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Publications (7)

SPIE Journal Paper | 10 September 2022 Open Access

Model-based characterization platform of fiber optic extended-wavelength diffuse reflectance spectroscopy for identification of neurovascular bundles

Yu Sun, Alexander Dumont, Mohammed Shahriar Arefin, Chetan Patil

JBO, Vol. 27, Issue 09, 095002, (September 2022) https://doi.org/10.1117/12.10.1117/1.JBO.27.9.095002

KEYWORDS: Tissues, Nerve, Model-based design, Short wave infrared radiation, Optical phantoms, Monte Carlo methods, Fiber optics, Systems modeling, Spectroscopy, Optical properties

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Significance: Fiber-optic extended-wavelength diffuse reflectance spectroscopy (EWDRS) using both visible/near-infrared and shortwave-infrared detectors enables improved detection of spectral absorbances arising from lipids, water, and collagen and has demonstrated promise in a variety of applications, including detection of nerves and neurovascular bundles (NVB). Development of future applications of EWDRS for nerve detection could benefit from the use of model-based analyses including Monte Carlo (MC) simulations and evaluation of agreement between model systems and empirical measurements.Aim: The aim of this work is to characterize agreement between EWDRS measurements and simulations and inform future applications of model-based studies of nerve-detecting applications.Approach: A model-based platform consisting of an ex vivo microsurgical nerve dissection model, unique two-layer optical phantoms, and MC model simulations of fiber-optic EWDRS spectroscopic measurements were used to characterize EWDRS and compare agreement across models. In addition, MC simulations of an EWDRS measurement scenario are performed to provide a representative example of future analyses.Results: EWDRS studies performed in the common chicken thigh femoral nerve microsurgical dissection model indicate similar spectral features for classification of NVB versus adjacent tissues as reported in porcine models and human subjects. A comparison of measurements from unique EWDRS issue mimicking optical phantoms and MC simulations indicates high agreement between the two in homogeneous and two-layer optical phantoms, as well as in dissected tissues. Finally, MC simulations of measurement over a simulated NVB indicate the potential of future applications for measurement of nerve plexus.Conclusions: Characterization of agreement between fiber-optic EWDRS measurements and MC simulations demonstrates strong agreement across a variety of tissues and optical phantoms, offering promise for further use to guide the continued development of EWDRS for translational applications.

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Proceedings Article | 2 March 2022 Paper

Reducing racial bias in transcutaneous measurements with mobile phone camera based spatially resolved diffuse reflectance

Brandon Harrison-Smith, Mohammed Arefin, Alexander Dumont, Chetan Patil

Proceedings Volume 11958, 1195804 (2022) https://doi.org/10.1117/12.2610519

KEYWORDS: Sensors, Calibration, Monte Carlo methods, Cell phones, RGB color model, Skin, Instrument modeling, Statistical modeling, Diffuse reflectance spectroscopy, Data modeling

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Proceedings Article | 2 March 2022 Presentation + Paper

Monte Carlo based simulations of racial bias in pulse oximetry

Mohammed Shahriar Arefin, Alexander Dumont, Chetan Patil

Proceedings Volume 11951, 1195103 (2022) https://doi.org/10.1117/12.2610483

KEYWORDS: Calibration, Monte Carlo methods, Oximeters, Oximetry, Oxygen, Statistical modeling, Hypoxia, Stochastic processes, Optical properties, Blood oxygen saturation

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Pulse oximetry is a common tool to perform a non-invasive optical estimate (SpO2) of arterial blood oxygen saturation level (SaO2). Although the principle of pulse oximetry has been established for a long time Recent clinical studies reported oximeter over-estimation bias in black patients. Measurement accuracy is an important factor, as over-estimation could impact clinical decision-making. Prior Monte-Carlo (MC) simulation-based studies showed increased melanin could reduce the oximeter signal intensity. These studies didn’t show the impact of pigmentation on calibration equation development in a population cohort. Extending MC simulations to study the influence of bias in calibration model enrollment, along with the corresponding optical estimation errors would offer insight into the basis of important clinical observations. Here, an MC simulation platform was developed to assess how pigmentation distribution in the racial demographics could impact calibration model development. MC simulations of oximeter measurements from <1200 simulated patient finger models were generated using a stochastic sampling-based technique, where patient optical properties (including pigmentation) were statistically assigned to generate a variation of measurements across different population cohorts. MC simulations of oximeter calibration studies representative of prior FDA 510(k) guidelines e.g.- minimum 20% darkly pigmented population) in comparison with alternative enrollment distributions. Performance of oximeter calibration equations was evaluated with unique population distributions of test subjects. Results showed that even if the calibration equations were developed from a representative population cohort, the predicted SpO2 show overestimation in high pigmentation cohorts. This over-estimation minimizes when the calibration is generated from distributions with an increased pigmented subject enrollment. The sensitivity to detect hypoxia in the highly pigmented cohort (sensitivity=0.95) is lower than the low pigmented cohort(sensitivity=0.98) when the representative population distribution was used to develop the calibration equation.

Proceedings Article | 19 March 2018 Presentation

Mobile phone based transcutaneous billirubinometry (Conference Presentation)

Brandon Harrison, Alexander Dumont, Hendrik Weitkamp, Chetan Patil

Proceedings Volume 10485, 1048505 (2018) https://doi.org/10.1117/12.2293845

KEYWORDS: Cell phones, Cameras, Diagnostics, Genetics, Visualization, Diffuse reflectance spectroscopy, Monte Carlo methods, Optical fabrication

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Proceedings Article | 13 February 2018 Paper

Development of accelerated Raman and fluorescent Monte Carlo method

Alexander Dumont, Chetan Patil

Proceedings Volume 10490, 104900P (2018) https://doi.org/10.1117/12.2293831

KEYWORDS: Raman spectroscopy, Luminescence, Raman scattering, Monte Carlo methods, Tissues, Tissue optics, Optical properties, Inspection, Tumors, Scattering

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Proceedings Article | 19 April 2017 Presentation

SWIR dispersive Raman spectroscopy for discrimination of normal and malignant kidney tissue (Conference Presentation)

Miki Haifler, Isaac Pence, Amnon Zisman, Robert Uzzo, Richard Greenberg, Alexander Kutikov, Marc Smaldone, David Chen, Rosalia Viterbo, Benjamin Ristau, Anita Mahadevan-Jansen, Alexander Dumont, Chetan Patil

Proceedings Volume 10038, 100380O (2017) https://doi.org/10.1117/12.2256617

KEYWORDS: Kidney, Remote sensing, Tissues, Tissue optics, Raman spectroscopy, Cancer, Computed tomography, Surgery, Tomography, Short wave infrared radiation

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Proceedings Article | 3 March 2017 Paper

Development of mobile phone based transcutaneous billirubinometry

Alexander Dumont, Brandon Harrison, Zachary McCormick, Nishant Ganesh Kumar, Chetan Patil

Proceedings Volume 10055, 100550T (2017) https://doi.org/10.1117/12.2257428

KEYWORDS: Cell phones, Monte Carlo methods, Diffuse reflectance spectroscopy, Cameras, Visualization, Skin, Optical fabrication, Tissue optics, Image analysis, Sensors, Absorption, Bismuth, Anisotropy, Reflectivity, Blood

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