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Proceedings Paper

Feasibility study of PDT light sources based on lasing action in strongly scattering media
Author(s): Lothar D. Lilge; Gendi Pang; James Jonkman; Brian C. Wilson
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Paper Abstract

Lasing action in strongly scattering media containing a fluorescent dye and pumped by a pulsed high peak power laser can be used to produce light sources which may be suitable for surface or intracavity light delivery in photodynamic therapy, eliminating the need for a dye laser to obtain selectable treatment wavelengths. The present study focuses on evaluating the effects, in cylindrical fiber tip sources for interstitial light delivery, of fluorophore concentration and scattering particle density on lasing peak power, emission wavelength and maximum deliverable, clinically useful fluence-rate and radiant exposure. The sources tested are comprised of Rhodamine 640 perchloride incorporated into a TiO2 based scattering matrix in either ethylene glycol or methanol. The cylindrical fiber tips, 10 mm long and 2 mm in diameter, were pumped via a 320 micrometers diameter multimode optical fiber, achieving line narrowing to approximately 7 nm FWHM at approximately 617 nm, using pulse energies of 1.7 mJ, delivered in 10 nsec from a Q-switched, frequency doubled Nd:YAG laser. The results showed the dependence of the total gain length in the pump volume and reabsorption effects in the remaining volume of the fiber tip. Sources capable of delivering sufficient radiant exposure for clinical use were achieved. While these sources are promising, for clinical use of these fiber sources pump lasers delivering MW pulses at high repetition rates are required to achieve acceptable total irradiation times.

Paper Details

Date Published: 8 May 1997
PDF: 6 pages
Proc. SPIE 2972, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy VI, (8 May 1997); doi: 10.1117/12.273497
Show Author Affiliations
Lothar D. Lilge, Ontario Laser and Lightwave Research Ctr. (Canada) and Univ. of Toronto (Canada)
Gendi Pang, Univ. of Toronto (Canada)
James Jonkman, Ontario Cancer Institute/Univ. of Toronto (Canada) and Univ. of Waterloo (Canada)
Brian C. Wilson, Ontario Laser and Lightwave Research Ctr. (Canada), Ontario Cancer Institute/Univ. of Toro (Canada)

Published in SPIE Proceedings Vol. 2972:
Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy VI
Thomas J. Dougherty, Editor(s)

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