Abstract

Photodynamic therapy (PDT) involves local activation of a drug called a photosensitizer (PS), whereby the PS accumulates in tumor tissue, and by means of light, the PS is activated. The activated PS reacts with triplet O₂ to produce singlet oxygen (van Lier 1990), which a result of its cytotoxic behavior, believed to be responsible for tumor destruction (Ethirajan et al. 2011). PSs are activated by light of specific wavelengths, and the depth that light will penetrate into tissue is wavelength dependent (Gudgin Dickson, Goyan, and Pottier 2002). Thus, the combination of PS and wavelength of light for PDT is determined by the location of the tumor (National Cancer Institute, 2011. http://www.cancer.gov/cancertopics/factsheet/Therapy/photodynamic).