A Monte Carlo estimation of tissue optical properties for use in laser dosimetry

Abstract

In certain clinical situations, such as photodynamic therapy, light dosimetry should be considered. The propagation of light in tissues is influenced by fundamental or microscopic optical properties, namely absorption mu a and scattering mu s coefficients, refractive index n and anistropy factor g. These optical parameters can be determined experimentally by direct and/or indirect methods when tissue macroscopic properties, such as reflectance, transmittance or collimated transmittance from a tissue slab, are measured. The method described in this work provides graphical, and in simple cases analytical, 'inverse' solutions to determine tissue microscopic properties from measured macroscopic parameters. The graphs necessary for this inversion have been calculated and are provided. The method can be applied in either direct or indirect techniques and it does not depend on limitations introduced by assumptions and approximations when using theoretical models. It can also be applied for any tissue type, detector geometry and experimental apparatus. The accuracy of the method is very good over a wide range, unlimited in practice, of values of optical properties. Finally, the results of this work are in good agreement with theoretical and experimental results of other investigators.

Quantitative correlation between light depolarization and transport albedo of various porcine tissues

“…In addition to their role in interpreting tissue polarimetry results, these measured optical properties may contribute to recent tissue optics compilations. [37][38][39][40] Polarized light imaging allows the construction of spatial maps in which the Mueller matrix derived parameters may be plotted. In Fig.…”

Optical properties of native and coagulated porcine liver tissue between 400 and 2400 nm

“…For calculating the optical parameters from the measured data, an inverse Monte Carlo simulation [10] was applied to precisely consider the geometric and optical conditions (sample geometry, sphere parameter, refractive index mismatch, etc.) and thus compensate for all systematic errors.…”

Optical properties of native and coagulated human liver tissue and liver metastases in the near infrared range

“…This stochastic procedure was developed for the simulation of physical processes. It was first applied in 1984 by Wilson [32] to examine radiation transport processes in biological tissue and has since been taken up by various authors [33][34][35]. The advantage of Monte Carlo simulation is that it enables precise consideration of the geometric and optical conditions (sample geometry, sphere parameters, refractive index, beam divergence, etc.).…”