Understanding light propagation in bone for applications in photodynamic therapy

My research is focused on applying photodynamic therapy (PDT) towards bone cancers. In PDT, inert photosensitizers (PS) are administered to targeted areas for treatment. Once illuminated by wavelengths specific to the absorption properties of each PS, the PS reaches an excited state and interacts with nearby oxygen, forming reactive species and free radicals. The reactive oxygen and free radicals then damage nearby cells. The goal of PDT is to create sufficient free radicals and reactive oxygen to destroy targeted sites. Before these techniques can be administered, the optical properties of various bone tissues at varying wavelengths need to be determined in order to effectively predict the penetration depths of incident light in treatment of bone cancers. I am currently working on the optical characterization of various bone samples - cancellous versus cortical, healthy versus cancerous. This characterization requires creating optically thin slices of bone (less than 10 microns thick) for characterization and the use of an integrating sphere for reflectance and transmission measurements. Additionally, I have a Monte Carlo simulation of photon propagation through a cylindrically symmetric medium as a first order approximation to the distribution of light incident on bone. By incorporating the optical characteristics of bone into the Monte Carlo simulation, my aim is to help guide clinical treatments of PDT in bone cancers. My research is done in collaboration with the OSU College of Veterinary Medicine and the Department of nutrition and Exercise Sciences, as well as the OHSU Departments of Dermatology and Biomedical Engineering.