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23 February 2011 Thermal effects in tissues induced by interstitial irradiation of near infrared laser with a cylindrical diffuser
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Proceedings Volume 7900, Biophotonics and Immune Responses VI; 79000B (2011)
Event: SPIE BiOS, 2011, San Francisco, California, United States
Laser immunotherapy (LIT), using non-invasive laser irradiation, has resulted in promising outcomes in the treatment of late-stage cancer patients. However, the tissue absorption of laser light limits the clinical applications of LIT in patients with dark skin, or with deep tumors. The present study is designed to investigate the thermal effects of interstitial irradiation using an 805-nm laser with a cylindrical diffuser, in order to overcome the limitations of the non-invasive mode of treatment. Cow liver and rat tumors were irradiated using interstitial fiber. The temperature increase was monitored by thermocouples that were inserted into the tissue at different sites around the cylinder fiber. Three-dimensional temperature distribution in target tissues during and after interstitial laser irradiation was also determined by Proton Resonance Frequency. The preliminary results showed that the output power of laser and the optical parameters of the target tissue determined the light distribution in the tissue. The temperature distributions varied in the tissue according to the locations relative to the active tip of the cylindrical diffuser. The temperature increase is strongly related to the laser power and irradiation time. Our results using thermocouples and optical sensors indicated that the PRF method is reliable and accurate for temperature determination. Although the inhomogeneous biological tissues could result in temperature fluctuation, the temperature trend still can be reliable enough for the guidance of interstitial irradiation. While this study provides temperature profiles in tumor tissue during interstitial irradiation, the biological effects of the irradiation remain unclear. Future studies will be needed, particularly in combination with the application of immunostimulant for inducing tumor-specific immune responses in the treatment of metastatic tumors.
© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Kelvin Le, Chet Johsi, Daniel Figueroa, Jessica Goddard, Xiaosong Li, Rheal A. Towner, Debra Saunders, Nataliya Smith, Hong Liu, Tomas Hode, Robert E. Nordquist, and Wei R. Chen "Thermal effects in tissues induced by interstitial irradiation of near infrared laser with a cylindrical diffuser", Proc. SPIE 7900, Biophotonics and Immune Responses VI, 79000B (23 February 2011);

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