Modeling of PDT kinetics in cell killing

Photodynamic therapy (PDT) provides an effective option for treatment of tumors and other diseases. In this work, we extended a previous rate-equation model in time domain with consideration of oxygen diffusion in a spherical cell model. Enhanced oxygen diffusion through cell membrane and non-PDT uptake of oxygen inside the cell have been investigated to study their effect on photobleaching and oxidization leading to cell killing within the context of PDT. We found that the improved PDT model can take into the account of the Michaelis-Menten uptake of the oxygen in addition to diffusion which allows quantitative modeling of photobleaching and cell killing.