Numerical modelling of photodynamic therapy

Abstract

Photodynamic Therapy (PDT) is a new and minimally invasive cancer treatment modality based on the photo-activation of a light-sensitive drug ‘Photosensitiser’ (PS). PS can be administered in various forms (e.g. as injection or ointment) and accumulates selectively in the target tumour tissue. This activated drug in turn generates singlet oxygen (1O2) in the malignant tissue and induces tissue necrosis or apoptosis. In this thesis, we have implemented a simulation model utilising the primary processes that the photosensitiser undergoes in the presence of irradiating light and molecular oxygen (3O2). We have used spectroscopic data of the commercially available and clinically significant photosensitiser ‘Photofrin®’ (porfimer sodium, Axcan Pharma, Montreal, Canada, a heterogeneous mixture of porphyrins). This model encourages predictive statements to be made regarding the efficiency of photodynamic modalities at various initial conditions, including PS concentration and tissue oxygen concentration.