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Proceedings Paper

mTHPC pharmacokinetics following topical administration
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Paper Abstract

Measurements of concentration of sensitizers for photodynamic therapy can provide important information in the dosimetry planning and can also give input to the optimal time for treatment. There has been skepticism towards fluorescence techniques for this purpose, as the signal depends on the fluorescence yield and optical properties of the tissue. Absorption based techniques, lack on the other hand, often the sensitivity required for many sensitizers with relative weak absorption in a wavelength region where hemoglobin absorption is dominant. A direct comparison between absorption and fluorescence techniques for measuring mTHPC concentration after topical application on hairless SKH-1 mice bearing skin carcinomas has been performed. 20 μl/cm2 of m-THPC thermogel (0.5 mg m-THPC/ml) were applied on normal and tumor area and the concentration of mTHPC was measured at 4 and 6 hours after drug application by two methods: 1. A fluorescence imaging system capturing images at two wavelengths (500 and 650 nm) following 405 nm excitation. Signals from different regions of interest were averaged and the intensity ratio at 650 to 500 was calculated. 2. A diffuse reflectance spectroscopy system with a fiber separation of 2 mm, providing the absorbance at 652 nm. Both systems provided consistent results related to the photosensitizer concentration. The methods show a remarkable difference in the concentration of photosensitizer in normal skin and tumor. No significant difference in mTHPC concentration in tumor could be observed between the 4 and 6h groups after drug application.

Paper Details

Date Published: 27 February 2006
PDF: 8 pages
Proc. SPIE 6094, Optical Diagnostics and Sensing VI, 60940C (27 February 2006); doi: 10.1117/12.647602
Show Author Affiliations
Ann Johansson, Lund Institute of Technology (Sweden)
Jenny Svensson, Lund Institute of Technology (Sweden)
Stefan Andersson-Engels, Lund Institute of Technology (Sweden)
Niels Bendsoe, Lund Univ. Hospital (Sweden)
Katarina Svanberg, Lund Univ. Hospital (Sweden)
Irving Bigio, Boston Univ. (United States)
Eleni Alexandratou, National Technical Univ. of Athens (Greece)
Maria Kyriazi, National Technical Univ. of Athens (Greece)
Dido Yova, National Technical Univ. of Athens (Greece)
Susanna Gräfe, CeramOptec GmbH (Germany)
Tilmann Trebst, Biolitec AG (Germany)


Published in SPIE Proceedings Vol. 6094:
Optical Diagnostics and Sensing VI
Gerard L. Coté; Alexander V. Priezzhev, Editor(s)

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