All about Photodynamic Therapy

PDT photosensitizers are specifically designed to be attracted to or absorbed by metabolically fast cells such as cancer cells and may be directly delivered to the treatment site, taken orally, or intravenously. Once the photosensitizer has been delivered, the site is exposed to a specific spectral band of light causing a series of reactions in the photosensitzer resulting in the formation of singlet oxygen. The singlet oxygen is itself a very aggressive chemical species causing damage to certain biological cells. That damage is confined to areas where the photosensitizer is present and then exposed to the PDT light source. In this respect, PDT is a very selective form of treatment since the mobility of the photosensitizer can be varied by delivery method and specific cells can be targeted by the careful design of the photosensitizer compounds. Even if other tissues have attracted or absorbed the photosensitizer and will be effected by the reaction, their unwanted damage is avoided by precise exposure of the desired treatment site to the PDT light source. Because of the high exposure precision required, lasers are often used due to their focused output and visible light output, which is the predominant portion of the spectrum used in PDT treatments. However, if a wavelength of light is required that is not producible from a laser or when a broader spectral output is needed, other types of light sources can be delivered to the treatment site with pinpoint accuracy via fiber optics.

Monitoring the amount of exposure to a PDT light source is absolutely critical in preventing unwanted tissue damage to the patient while maintaining the desired efficacy. International Light Technologies has a selection of PDT-specific systems designed for highly accurate intensity, exposure, and spectral wavelength measurement of a wide array of PDT light sources in both laboratory and clinical environments.