Advances in Photodynamic Therapy Dosimetry

Photodynamic therapy (PDT) is an emerging therapeutic modality based on the interaction of light, photosensitizer and molecular oxygen. As PDT techniques continue to develop and find more potential clinical indications, accurate dosimetry becomes a critical factor for achieving satisfied individual treatments. The current status of strategies and corresponding technologies for PDT dosimetry are reviewed. Typical PDT dosimetry estimations include the direct measurement of three critical ingredients of PDT (i.e. fluence rate, photosensitizer concentration, and tissue oxygen pressure), indirect determination of the photosensitizer fluorescence photobleaching and photoproduct formation, monitoring biological responses, and detecting singlet oxygen production with its near-infrared luminescence around 1 270 nm. The advantages and limitations of each PDT dosimetric model will be presented and the main challenges in clinical PDT dosimetry will be discussed.