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Optical Engineering

Photodynamic tumor therapy and on-line fluorescence spectroscopy after ALA administration using 633-nm light as therapeutic and fluorescence excitation radiation
Author(s): Karsten Koenig; Alwin Kienle; Wolf-Henning Boehncke; Roland Kaufmann; Angelika C. Rueck; Thomas H. Meier; Rudolf W. Steiner
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Paper Abstract

Photodynamic therapy (PDT) and on-line fluorescence spectroscopy were carried out on human tumors after 5-aminolevulinic acid (ALA) administration using 633-nm light of a dye laser as therapeutic radiation and as fluorescence excitation radiation. This has the advantages of (1) enabling use of one laser for PDT and fluorescence diagnosis only, (2) enabling the possibility of on-line fluorescence measurements, and (3) exciting protoporphyrin molecules in deep tissue layers. Monte Carlo calculations were carried out to determine excitation and fluorescence photon distribution in case of red and violet excitation radiation. The results show the possibility of depth-resolved measurements on the fluorophore distribution by variation of excitation wavelength. The high penetration depth of 633-nm radiation results in a higher ratio of the 700-nm protoporphyrin fluorescence of the xenotransplanted tumor It to the skin Is compared with 407-nm excitation. No values greater than 1 for the ratio It/Is were found in the case of intravenous ALA injection even for red excitation. Therefore, a large amount of ALA will be metabolized in the skin and can cause photosensitivity of the patient when applied systematically. In contrast, protoporphyrin fluorescence limited to the pretreated skin area was detected in case of topically applied ALA to patients with mycosis funcoides and erythroplasy of Queyrat. The influence of remitted excitation light and of the spontaneous radiation from the laser as well as the possible excitation of food-based degradation products of chlorophyll has to be considered in high-sensitivity fluorescence measurements.

Paper Details

Date Published: 1 September 1994
PDF: 8 pages
Opt. Eng. 33(9) doi: 10.1117/12.177511
Published in: Optical Engineering Volume 33, Issue 9
Show Author Affiliations
Karsten Koenig, Beckman Laser Institute and Medical Clinic (Germany)
Alwin Kienle, Univ. Ulm (Germany)
Wolf-Henning Boehncke, Univ. Ulm (Germany)
Roland Kaufmann, Univ. of Ulm (Germany)
Angelika C. Rueck, Univ. Ulm (Germany)
Thomas H. Meier, Univ. Ulm (Germany)
Rudolf W. Steiner, Univ. Ulm (Germany)

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