Light Delivery and Optical Dosimetry in Photodynamic Therapy of Solid Tumors

The clinical effectiveness of photodynamic therapy (PTD) for treatment of solid tumors depends on the appropriate delivery of both light and photosensitizer to the target tumor tissue. This chapter emphasis on the various concepts, methods, and instruments that have been developed for optimal delivery and control of light distributions in tissue. It shows how optical approaches may also be used to provide quantitative information on the uptake and, possibly, the distribution of photosensitizer in tissue. The requirement for light sources and delivery systems in PDT is to achieve adequate irradiation throughout the target tissue volume. The foregoing discussion relates to physical dosimetry in PDT and takes no account of the biological response of the tissue, which clearly depends both on the concentration of cytotoxic photoproducts and on the intrinsic photosensitivity. The “standard” current light source for clinical PDT of solid tumors is a tunable dye laser, pumped by an argon ion laser.