In this study we present a complex approach to photodynamic therapy (PDT) with chlorin based photosensitizers including Monte Carlo based planning and prediction of optical diagnostics results, intra-procedure dual-wavelength fluorescence monitoring allowing to evaluate PS accumulation and photobleaching, and monitoring of tissue response with optical coherence tomography (OCT). The approach was employed to compare the effects of different PDT regimens in normal and tumor tissues and the results of non-invasive optical diagnostics were matched with results of histologic examination, including hematoxylin-eosin and Mallory staining. The considered doses are in the range 50-150 J/cm<sup>2</sup> for normal tissues and 150-275 J/cm<sup>2</sup> for tumor tissues, single wavelength (405 and 660 nm) and dual-wavelength regimes are studied.
Dual-wavelength photodynamic therapy is a photodynamic therapy (PDT) modality combining therapeutic effects of irradiation at two wavelengths of different region of visible range. In this paper we report on comparative analysis of single- and dual-wavelength PDT regimes based on multimodal optical monitoring of tissue response with histologic verification. Morphological and functional tissue responses to PDT procedure with chlorin-based photosensitizer (PS) were studied at the normal skin of a rabbit ear inner surface. Multimodal optical monitoring was performed by OCT and dual-wavelength fluorescence technique. The studied doses vary from 50 to 150 J/cm<sup>2</sup> delivered separately at 405 or 660 nm, or at both wavelengths together in the equal dose.