PDT Basics

Photodynamic Theapy | PDT Control | Fluorescent Diagnostics

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Photodynamic therapy (PDT) now provides treatment options in many areas through the use of light-activated substances and the corresponding lasers. As a result, patients suffering from illnesses ranging from acne to cancer can be treated efficiently and safely. The market is anticipating solutions such as photodynamic therapy. Therapeutic classes include age-related macular degeneration, periodontosis, hair loss, Barrett’s syndrome, arteriosclerosis and cancer therapy.

Photodynamic Therapy

Photodynamic therapy is a new form of treatment for diseases and cosmetic indications triggered by fast-growing pathologic cells or bacteria. In this therapy, an active light-sensitive substance, photosensitizer, is administered either locally to the affected tissue or to the whole organism. The photosensitizer accumulates in different concentrations in various tissue and cell types but mainly in pathologic tissue. The photosensitizer only becomes effective when activated by light radiation. Light wavelength is matched to the absorbing properties of the phototherapeutic agent. Light energy from the laser is beamed at the specific treatment location and absorbed by the sensitizer. The light is supplied either from the outside (UFPh-630/675-01-BIOSPEC) or endoscopically through optical fibers (LPhT-630/675-01-BIOSPEC). Light triggers a photochemical reaction but does not cause any heat damage. During this process, the sensitizer transitions to an energy-rich state. This energy generates reactions attacking the pathologic cells, thereby destroying cell components such as membranes and proteins. As a result, the affected cell dies and the concerned tissue is destroyed and broken down. The exact treatment location is determined and controlled by the selective accumulation of the photosensitizer and the targeted use of the laser. This reduces side effects to a minimum and ensures that no damage is caused to adjacent areas or organs. As opposed to e.g. chemotherapy, photodynamic therapy is considered largely free of side effects. The application of photodynamic therapy requires the key components of photosensitizer accumulated in pathologic tissue, oxygen participating in photochemical reaction and light. Only the proper combination of these three components brings to considerable results.


PDT Control

Effective therapy is impossible without accurate measurements of a photosensitiser concentration in pathologic tissues and adjacent areas. LESA-01-BIOSPEC is a unique system allowing in vivo quantitative measurements of phototherapeutic agent concentration using its fluorescence and absorbing properties. Modifications of LESA-01-BIOSPEC allow estimating oxygenation degree in capillary blood flow.

The size and borders of the tumor are determined by visualization techniques and devices employing video cameras (UFPh-630/675-01-BIOSPEC), allowing it to see the fluorescence of a tumor on the screen of the monitor.


Fluorescent Diagnostics

For the fluorescent diagnostics (FD) we can study either the natural autofluorescence of background of the concerned tissue, or the distribution of fluorescence for an exogen fluorochrome, for example one of those used in photodynamic therapy, or the combination of the two methods. Very high sensitivity of LESA-01-BIOSPEC permits to use both methods.



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