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Proceedings Paper

Applications of time-resolved light scattering measurements to photodynamic therapy dosimetry
Author(s): Michael S. Patterson; John David Moulton; Brian C. Wilson; Britton Chance
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Paper Abstract

Since biological response to photodynamic therapy (PDT) depends on the light fluence distribution and photosensitizer concentration in the tissue, these two variables should ideally be measured noninvasively in individual cases. This can be reduced to determining the optical absorption and transport scattering coefficients of the tissue because, if these two parameters are known, the fluence distribution can be calculated and the photosensitizer concentration can be deduced from its characteristic contribution to the absorption spectrum. The temporal spreading of a picosecond laser pulse as it propagates through tissue carries infonnation about both the scattering and absorption properties of the tissue. A mathematical model is presented which allows derivation of the interaction coefficients from the pulse shape, and preliminary experiments are reported which demonstrate the potential of these techniques in PDT dosimetry. Equivalent information can be obtained in the frequency domain by using modulated light sources andmeasuring thephase and modulation of the detected light. Analytical expressions are developed for these observable quantities in terms ofthe optical interaction coefficients. Particular auention is drawn to the potential oflow (less than 200 MHz) frequency measurements as these can be made with relatively simple instrumentation.

Paper Details

Date Published: 1 July 1990
PDF: 14 pages
Proc. SPIE 1203, Photodynamic Therapy: Mechanisms II, (1 July 1990); doi: 10.1117/12.17652
Show Author Affiliations
Michael S. Patterson, Hamilton Regional Cancer Ctr. and McMaster Univ. (Canada)
John David Moulton, Hamilton Regional Cancer Ctr. and McMaster Univ. (Canada)
Brian C. Wilson, Hamilton Regional Cancer Ctr. and McMaster Univ. (Canada)
Britton Chance, Univ. of Pennsylvania (United States)

Published in SPIE Proceedings Vol. 1203:
Photodynamic Therapy: Mechanisms II
Thomas J. Dougherty, Editor(s)

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