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Proceedings Paper

Repetition-rate-dependent oxygen consumption modifies cytotoxicity in photodynamic therapy using pulsed light
Author(s): Satoko Kawauchi; Yuji Morimoto; Hiroshi Asanuma; Hiroyuki Sato; Tsunenori Arai; Shunichi Sato; Isao Sakata; Takeshi Takemura; Susumu Nakajima; Makoto Kikuchi
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Paper Abstract

We studied the repetition-rate dependence of PDT cytotoxicity and relation between PDT cytotoxicity and both oxygen consumption and photobleaching during PDT in vitro. Mice renal carcinoma cells were incubated wtih second-generation photosensitizier, PAD-S31, and were irradiated with 670-nm nanoseconds pulsed light from YAG-OPO system. Four repetition rates of 30, 15, 5 and 3 Hz were investigated, provided that the incident peak intensity and the total light dose adjusted to 1.2 MW/cm2 and 40 J/cm2, respectively. We found limited cytotoxicity about 40% at 30 and 15 Hz and sufficient cytotoxicity about 80% at 5 and 3 Hz. The oxygen measurement during irradiation revealed that the 5- and 30Hz irradiation caused slow oxygen consumption, while rapid oxygen consumption followed by a rapid recovery of oxygenation at 30 and 15 Hz. Interestingly, the fluorescence measurement during irradiation also demonstrated that photobleaching discontinued in the same period of oxygen recovery at 30 and 15 Hz. These discontinued oxygen consumption and photobleaching at 30 and 15 Hz might have limited effective total fluence and resulted in suppressed cytotoxicity. These results suggest that the PDT efficacy using a pulsed laser significantly depends on the pulse repetition rate probably due to different oxygen consumption process during PDT.

Paper Details

Date Published: 13 June 2003
PDF: 6 pages
Proc. SPIE 4952, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XII, (13 June 2003); doi: 10.1117/12.474150
Show Author Affiliations
Satoko Kawauchi, National Defense Medical College (Japan)
Yuji Morimoto, National Defense Medical College (Japan)
Hiroshi Asanuma, Tokyo Metropolitan Kiyose Children's Hospital (Japan)
Hiroyuki Sato, Tokyo Metropolitan Kiyose Children's Hospital (Japan)
Tsunenori Arai, Keio Univ. (Japan)
Shunichi Sato, National Defense Medical College (Japan)
Isao Sakata, Photochemical Co. (Japan)
Takeshi Takemura, Photochemical Co. (Japan)
Susumu Nakajima, Obihiro Univ. (Japan)
Makoto Kikuchi, National Defense Medical College (Japan)

Published in SPIE Proceedings Vol. 4952:
Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XII
David Kessel, Editor(s)

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