Human Skin and Tissue Phantoms in Optical Software: Engineering Design and Future Medical Applications

Abstract

Recent breakthroughs in Breault Research Organization's ASAP® optical software have resulted in a highly accurate method for skin and tissue modeling via the Henyey-Greenstein approximation for the angular distribution of scattered light and the radiative-transport equation. Four parameters are key to the model: the anisotropy factor (g), the scattering coefficient (μs), the absorption coefficient (μa), and the fractional obscuration per unit area (f) -- the former three of which are wavelength (λ) dependent. The wavelength dependence of light-absorbing and scattering molecules, including eumelanin, pheomelanin, deoxy- and oxy-hemoglobin, bilirubin, beta carotene, and water is known over the wavelength range from 250 nanometers to 1 micron. The ASAP Realistic Skin Model™ and Tissue Generator have enabled virtual modeling for a wide range of tissue-optics problems. Researchers may now simulate light interactions in the stratum corneum, epidermis, dermis, and hypodermis of human skin -- with provisions for hair, blood vessel, dermal papillae, and fluorescence characterization -- as well as single and multilayer tissue models based on bulk-scattering approximations. Commercial applications for these models include medical-device design and treatment-efficacy studies involving light delivery and detection. Future applications may include real-time monitoring of bio-optical phenomena, and patient-specific pre-treatment studies for cancer and other diseases for which light-based therapies are emerging.