PDT Study Using a Model Incorporating Initial Oxygen Concentration and Blood Flow Increase

Type II photodynamic therapy (PDT) is an experimental modality for cancer treatment based on the combined action of a photosensitizer, a special wavelength of light and singlet oxygen (O2) generation. The cell killing is caused by the reaction of cellular acceptors with O2. A mathematical model has been previously developed to incorporate the macroscopic kinetic equations for O2 generation, photosensitizers in ground and triplet states, oxygen (O2), and tissue acceptors along with the diffusion equation for the light transport in tissue. Accurate estimation of the tissue oxygen changes during PDT is influenced by initial oxygen concentration ([O2]0) and blood flow, so that incorporation of different [O2]0 and blood flow changes in our model allows a better calculation of the O2 generation. In this study, the effects of [O2]0, as well as the changes of the blood flow during PDT, on the magnitude of O2 generation is studied.