Light photodynamic therapy

Note To be used in conjunction with the Blue Light Photodynamic Therapy Illuminator... 

The development of so-called photodynamic therapy uses lasers for treatment of cancer. The patient is injected with a substance called hematoporphyrin derivative [68335-15-9] which is preferentially localized in cancerous tissues. The patient is later irradiated with laser light, often with a dye laser at a wavelength around 630 nm. The light energy catalyticaHy photooxidizes the hematoporphyrin derivative, releasing materials which kill the nearby cancerous tissue. Normal tissue which did not retain the chemical is not harmed. Photodynamic therapy offers promise as a new form of cancer treatment. 

Use of coherent light sources in industrial appHcations has led to the field of photodynamic therapy as a photochemically based medical technology (9—11). The apphcation of photochemistry to information storage and communication processes is expected (12) (see Information storage materials Resist materials). 

Photodynamic therapy uses non-thermal red light to activate verteporfin, which produces reactive oxygen species that locally damage the neovascular endothelium.24 Verteporfin treatment reduces the risk of loss of visual acuity and legal blindness over 1 to 2 years. Long-term results are not yet available. Severe photosensitivity for 3 to 5 days after the procedure is common and some patients experience a severe loss of vision. Eventually, most patients have some visual recovery. This procedure requires multiple treatments over time.22... 

Photodynamic therapy is based on a phenomenon known as photodynamic action, or the photodynamic effect, which are terms used to describe the damage to living tissue caused by certain photosensitizers in the presence of visible light and oxygen. Again, there is an extensive historical record, which has been reviewed several times during the 1990s.4,9-15... 

Presently photodynamic therapy (PDT) is considered as a perspective way for therapy of different diseases, including cancer. PDT is a method based on the local light-induced activation of photosensitizers able to accumulate selectively in energy-deficient cells (malignant or dysplastic ones) not influencing the remaining normal cells of the body (Pass, 1993). Upon the action of irradiation of certain wavelength characteristic for individual photosensitizer, photochemical reaction occurs... 

Phototherapy is the generic term covering therapies which use light either with or without a sensitiser. Those that do not require a sensitiser use the natural chromophores within the tissue to perform this function e.g. treatment of vitamin D deficiency in rickets, and neonatal jaundice). Those that do use an added sensitiser include photochemotherapy (largely psoriasis and skin disorders) and photodynamic therapy (currently mainly cancer). Photodynamic therapy is differentiated from photochemotherapy by its additional requirement for the presence of oxygen at molecular or ambient levels.In this text we will deal only with photodynamic therapy since, at the present time, this is the main driving force in phototherapy. ° ... 

Prates, R. A., da Silva, E. G., Yamada, A. M., SuzuU, L. C., Paula, C. R., and Ribeiro, M. S. (2009). Light parameters influence cell viability in antifungal photodynamic therapy in a fluence and rate fluence-dependent manner. Laser Phys. 19(5), 1038-1044. 

Since not all tissues are as biochemically unique as hormone-secreting organs, other approaches have been explored in an attempt to achieve tumor-specific killing while sparing other tissues. Photodynamic therapy is such an approach. This type of therapy is based upon the accumulation of a dmg molecule within the tumor, followed by a light-mediated... 

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