Estimation of Rabbit Pancreas Dispersion Between 400 and 1000 nm

Abstract

Current biophotonics methods cover the entire optical spectrum from the deep ultraviolet to the terahertz. To optimize such methods for diagnostic and therapeutic applications, the need to obtain the wideband dispersion of tissues is high. The pancreas is a very important organ in the human body, since it produces insulin and its malfunction may induce diabetes. A reduced number of biophotonics publications regarding the pancreas is available, meaning that studies to determine its optical properties and their variation during optical clearing treatments are necessary. Considering this fact, we used the total internal reflection method to measure the refractive index of the rabbit pancreas for wavelengths between 400 and 850 nm. The experimental results allowed to calculate the pancreas dispersion with the Cauchy, Conrady and Cornu equations. It was observed that all those equations provided good data fitting in the spectral range of the measurements, but differences were observed outside these limits. Considering the wavelength of 633 nm, the mean value from the three dispersions was 1.3521, while the one published for porcine pancreas is 1.3517. The dispersion calculated with the Conrady equation does not present a fast decreasing behavior for shorter wavelengths as the ones calculated with the Cauchy and Cornu equations, but comparing these curves with a dispersion for a tissue-like material, all seem to have good agreement.

Fast Estimation of the Spectral Optical Properties of Rabbit Pancreas and Pigment Content Analysis

“…Such a calculatio made ten times, leading to the mean and SD for μs(λ) that is represented in F obtain the λ-dependence for μ′s and according to the procedure described in After obtaining µ a (λ), it was used in the K-K relations (Equations ( 2) and ( 3)) to obtain n tissue (λ). Such a calculation was optimized by adjusting λ 1 in Equation ( 3) to match n tissue (λ) to the Cornu-type dispersion that was previously calculated from discrete RI measurements [28]. These calculations were made 10 times and the mean results are presented in Figure 4.…”

“…After obtaining μa(λ), it was used in the K-K relations (Equations ( 2) and (3 ntissue(λ). Such a calculation was optimized by adjusting λ1 in Equation ( 3) to ma to the Cornu-type dispersion that was previously calculated from discrete R ments [28]. These calculations were made 10 times and the mean results are p Figure 4.…”

“…where Λ represents the integrating variable over the spectral range of interest and λ 1 is a fixed λ that can be adjusted for a better vertical matching of the calculated dispersion to a Cornu-type dispersion, which was calculated based on discrete experimental RI data that was available from a previous study [28]. Such a calculation was also made 10 times to obtain the mean and SD of n tissue (λ);…”

“…A recent paper has reported the differences between the blood microcirculation in normal and in diseased rat pancreas with induced alloxan diabetes [27]. Another recent paper presents discrete experimental refractive index (RI) data and the calculated dispersion between 400 and 1000 nm for the rabbit pancreas [28]. Although these two studies are most valuable for the application of optical methods to the pancreas, the evaluation of its optical properties over a wide spectral range is still necessary to plan further diagnostic optical methods.…”