Fig. 1.

Photodynamic therapy as a single modality for therapy and imaging. Photosensitizer (PS) is administered systemically, following which it preferentially localizes at the desired site. The time delay following PS administration and its subsequent irradiation is referred to as the drug-light-interval. Irradiation of the PS results in reactive molecular species generation and fluorescence emission, which could be used for inducing cytotoxicity and imaging, respectively.