Study on photo-damage selectivity in photodynamic therapy by means of Monte Carlo method

The purpose is to provide insight into the issue of photo-damage selectivity in photodynamic therapy.Monte Carlo simulation was performed using different optical property for normal and tumor tissue.The decay of photodynamic dose with depth was approximately exponential.The greater depth of effect of increasing photodynamic dose obtainable in the tumor/normal simulation is clear as the greater depth of completely selective damage is,which has a threshold photodynamic dose for tissue necrosis and is affected by the photo spot size.For typical photosensitizer retention ratios,it is possible to obtain a shallow but entirely selective depth of tumor necrosis,but to obtain deeper tumor necrosis necessarily means some degree of normal tissue damage.