Photodynamic Therapy - Procedure

Procedure

In order to achieve the selective destruction of the target area using PDT while leaving normal tissues untouched, either the photosensitizer can be applied locally to the target area or photosensitive targets can be locally excited with light. For instance, in the treatment of skin conditions, including acne, psoriasis, and also skin cancers, the photosensitizer can be applied topically and locally excited by a light source. In the local treatment of internal tissues and cancers, after photosensitizers have been administered intravenously, light can be delivered to the target area using endoscopes and fiber optic catheters (see figure).

Photosensitizers can also target many viral and microbial species, including HIV and MRSA. Using PDT, pathogens present in samples of blood and bone marrow can be decontaminated before the samples are used further for transfusions or transplants. PDT can also eradicate a wide variety of pathogens of the skin and of the oral cavities. Given the seriousness that drug resistant pathogens have now become, there is increasing research into PDT as a new antimicrobial therapy.

Over the last thirty years, PDT has seen considerable development in a wide range of medical applications. At the cutting edge of new PDT developments, many scientists worldwide are exploring ways of enhancing photosensitizer efficacy and targeting, while new research in Russia looks to use PDT to kill internal pathogens such as mycobacterium tuberculosis, and a significant development in Asia involves whole body Next Generation PDT (NGPDT) using a tumour-specific chlorophyll-based photosensitizer to treat a wide variety of solid cancers, including deep tissue and multisite cancers.