Time-resolved optical fluorescence spectroscopy of heterogeneous turbid media with special emphasis on brain tissue structures including diseased regions: A sensitivity analysis

Abstract

is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. b s t r a c tFluorescence-enhanced optical imaging based on near-infrared light provides a promising tool to differentiate diseased lesions from normal tissue. However, the measurement sensitivity of the fluorescence signals acquired at the output surface of the tissue is greatly influenced by the tissue structure, the optical properties, the location and the size of the target. In this paper, we present a numerical model based on the Monte Carlo method that allows to simulate time-resolved reflectance signals acquired on the surface of the scalp of a human head model bearing a fluorescent diseased region (tumor, glioma). The influence of tumor depth, tumor size and tumor shape evolution on the computed signals are analyzed by taking into account the multi-layered tissue structure. The simulations show that the mean-time-of-flight and the difference between two mean-times acquired at two source-detector distances are both relevant to this problem type. Furthermore, the simulations suggest that the use of the difference between mean-flight-times may be interesting to probe scattering changes that occur in the cerebrospinal fluid (CSF).

Influence of the size and skin thickness of apple varieties on the retrieval of internal optical properties using Vis/NIR spectroscopy: A Monte Carlo-based study

“…1(a) and (b)). The code provided by Wang et al (1995) was essentially modified to simulate the time-domain reflectance spectroscopy (Vaudelle and L'Huillier, 2013), where a very short light pulse ($4-5 ps) enters at one point at the edge of the spherical model, experiences complicated paths inside the two-layer turbid model, before reaching the detector located at some distance from the light entry point. The detector will then measure photon time-of-flight distributions which are comparable to those recorded in TCSPC operations.…”

“…Finite element (Arridge et al, 1993;Aydin et al, 2005;Deulin and L'Huillier, 2006), Boundary element (Fedele et al, 2005) and discrete ordinates (Tuchin, 1997) methods have successfully been used to model light transport in various turbid media. Monte Carlo method previously reported by Wang et al (1995) has been often adapted to predict light propagation in multilayered tissues such as human head (Okada et al, 1997;Boas et al, 2002;Mansouri et al, 2010;Vaudelle and L'Huillier, 2013), skin (Verkruysse et al, 1993), aorta (Keijzer et al, 1989) and in other tissue arrangements (Zolek et al, 2006;Guo et al, 2008). The Monte Carlo method seems also to be especially promising in the context of food and agricultural products.…”

Numerical Study of Light Transport in Apple Models Based on Monte Carlo Simulations

“…Because the diffusion approximation is inaccurate near the boundary, application of these models requires that the thickness of the first layer be larger than its reduced transport mean free path (1/µ a + µ' s ). Other works have described numerical methods based on finite element [24][25][26] and Monte Carlo (MC) [6,[27][28][29][30][31][32][33][34] models to simulate light transport in various complex multilayered biological structures. The Monte Carlo method has also been successfully used in the context of food and agricultural products for predicting optical features related to apples [20,35], kiwi fruit [36], and onion bulbs [37].…”

Light source distribution and scattering phase function influence light transport in diffuse multi-layered media

“…These probabilities estimate length of free paths, direction changes, absorption and Fresnel reflection for the different boundaries [11,12], and depend on the optical coefficients µ s , µ a , g, and n/n ext (relative index of refraction). Monte Carlo methods have been widely used for several transport problems [13,14] and for numerical simulations of photon propagation in multilayered biological tissues [15][16][17][18][19] or within tissue-like diffusing phantoms [20,21]. The knowledge of laser light transport through the human skin allows to improve therapy applications [17], cosmetic analysis [22], or to reproduce the human face with more accuracy [5].…”