White light diffuse optical spectroscopy for therapy monitoring

Abstract

Since its rediscovery in 1973, Photodynamic Therapy (PDT) has emerged to be one of the novel cancer treatment modalities. In its very essence, it exploits light-activated drugs or better known as photosensitisers, and laser light to induce selective cytotoxicity. The effect of photosensitiser concentration, blood oxygenation level, and sufficient light on the site play a major role in PDT’s clinical success.[1] A non-invasive therapy monitoring method is simplified by the development of Diffuse Optical Spectroscopy (DOS), where several important chromophores such as oxygenated haemoglobin (HbO2), deoxygenated haemoglobin (Hb), and photosensitiser concentration can be monitored constantly to provide a preliminary overview on the therapy progress[2] for clinicians to chart the subsequent courses of action.