Predicting optoacoustic spectral behaviour of human erythrocytes, stomatocytes and echinocytes using a modified Green’s function method

Saha, Ratan K.

doi:10.1007/s00249-021-01579-5

Cited by 2 publications

(3 citation statements)

References 25 publications

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“…In this work, the MGF approach has been used to calculate the OA spectra for normal and pathological RBCs. In this method, the mismatch in speed of sound is incorporated within the Green's function which results in better estimation of OA spectrum compared to the GF method [2]. It is worthy to mention that the locations of minima for each case in the MGF scheme appear little later than those of the GF protocol.…”

Section: Discussionmentioning

confidence: 99%

“…It has been recently shown that an approximate solution can also be obtained by consiedering only the first term of Eq. ( 5) and using a modified Green's function, which in the far field takes the following forms [2,5],…”

Section: Theoretical Components and Numerical Implementationmentioning

confidence: 99%

“…Red blood cells (RBCs) under normal biophysical and biochemical condition retain biconcave shape [1,2] maximizing surface to volume ratio, which help them to perform regular physiological activities efficiently. Some hereditary disorders make RBCs stiff and deformed posing difficulties to perform their regular functions.…”

Section: Introductionmentioning

confidence: 99%

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Estimation of photoacoustic spectra for normal and pathological red blood cells using a modified Green’s function approach

Saha,

Mandal

2023

Opto-Acoustic Methods and Applications in Biophotonics VI

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The frequency domain optoacoustic (OA) wave equation is inherently inhomogeneous. The first inhomogeneous term arises because of the OA effect (i.e., conversion of optical energy into acoustical energy).The second term appears due to sound-speed mismatch between the source and the ambient medium. The conventional Green's function method works well in absence of the second term (i.e., acoustically homogeneous source). Recently, it has been shown that a modified Green's function (MGF) approach provides faithful solution to the OA wave equation for an acoustically inhomogeneous source. Herein, we employ the MGF technique for accurate estimation of the OA spectra for normal and pathological red blood cells (RBCs). The shapes in 2D mimicking normal RBC, stomatocyte and echinocyte (with six equidistant identical spicules) were simulated (with constant area ≈ 16.5 µm 2 ) and subsequently, the OA spectra were computed over 10-1000 MHz by evaluating the integral equation employing the Monte Carlo integration method. The OA spectrum for an equivalent disc was also calculated for comparison. The sound-speed within the source region was taken as 1639 m/s and that of the surrounding medium was chosen as 1500 m/s. The first minimum of the OA spectra for disc and echinocyte appeared almost at the same location (440 MHz) when probed from an angle, θ=π/4 with respect to the axis of symmetry. The locations for the first minimum became 280 and 390 MHz, respectively for normal RBC and stomatocyte (for θ=π/4). These 0A spectral features may be useful for morphological characterization of normal and deformed RBCs.

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Section: Discussionmentioning

confidence: 99%

Section: Theoretical Components and Numerical Implementationmentioning

confidence: 99%

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Estimation of photoacoustic spectra for normal and pathological red blood cells using a modified Green’s function approach

Saha,

Mandal

2023

Opto-Acoustic Methods and Applications in Biophotonics VI

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Quantitative evaluation of the impact of variation of optical parameters on the estimation of blood hematocrit and oxygen saturation for dual-wavelength photoacoustics

Paul,

Patel,

Saha

2024

J. Opt. Soc. Am. A

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Photoacoustic (PA) spectroscopy is considered to be one of the most effective ways to measure the levels of hematocrit (H) and oxygenation saturation (SO2) of blood, which are essential for diagnosing blood-related illnesses. This simulation study aims to investigate the impact of individual optical parameters, i.e., optical absorption coefficient (μ a ), scattering coefficient (μ s ), and anisotropy factor (g), on the accuracy of this technique in estimating the blood properties. We first performed the Monte Carlo simulations, using realistic optical parameters, to obtain the fluence maps for various samples. The wavelengths of the incident light were chosen to be 532, 700, 1000, and 1064 nm. Thereafter, the k-Wave simulations were executed, incorporating those fluence maps to generate the PA signals. The blood properties were obtained using the PA signals. We introduced variations in μ a , μ s , and g ranging from −10% to +10%, −10% to +10%, and −5% to +1%, respectively, at 700 and 1000 nm wavelengths. One parameter, at both wavelengths, was changed at a time, keeping others fixed. Subsequently, we examined how accurately the blood parameters could be determined at physiological hematocrit levels. A 10% variation in μ a induces a 10% change in H estimation but no change in SO2 determination. Almost no change has been seen for μ s variation. However, a 5% (−5% to 0%) variation in the g factor resulted in approximately 160% and 115% changes in the PA signal amplitudes at 700 and 1000 nm, respectively, leading to ≈125% error in hematocrit estimation and ≈14% deviation in SO2 assessment when nominal SO2=70%. It is clear from this study that the scattering anisotropy factor is a very sensitive parameter and a small change in its value can result in large errors in the PA estimation of blood properties. In the future, in vitro experiments with pathological blood (inducing variation in the g parameter) will be performed, and accordingly, the accuracy of the PA technique in quantifying blood H and SO2 will be evaluated.

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Predicting optoacoustic spectral behaviour of human erythrocytes, stomatocytes and echinocytes using a modified Green’s function method

Cited by 2 publications

References 25 publications

Estimation of photoacoustic spectra for normal and pathological red blood cells using a modified Green’s function approach

Estimation of photoacoustic spectra for normal and pathological red blood cells using a modified Green’s function approach

Quantitative evaluation of the impact of variation of optical parameters on the estimation of blood hematocrit and oxygen saturation for dual-wavelength photoacoustics

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