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8 April 2005 System for integrated interstitial photodynamic therapy and dosimetric monitoring
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Photodynamic therapy for the treatment of cancer relies on the presence of light, sensitizer and oxygen. By monitoring these three parameters during the treatment a better understanding and treatment control could possibly be achieved. Here we present data from in vivo treatments of solid skin tumors using an instrument for interstitial photodynamic therapy with integrated dosimetric monitoring. By using intra-tumoral ALA-administration and interstitial light delivery solid tumors are targeted. The same fibers are used for measuring the fluence rate at the treatment wavelength, the sensitizer fluorescence and the local blood oxygen saturation during the treatment. The data presented is based on 10 treatments in 8 patients with thick basal cell carcinomas. The fluence rate measurements at 635 nm indicate a major treatment induced absorption increase, leading to a limited light penetration at the treatment wavelength. This leads to a far from optimal treatment since the absorption increase prevents peripheral tumor regions from being fully treated. An interactive treatment has been implemented assisting the physician in delivering the correct light dose. The absorption increase can be compensated for by either prolonging the treatment time or increasing the output power of each individual treatment fiber. The other parameters of importance, i.e. the sensitizer fluorescence at 705 nm and the local blood oxygen saturation, are monitored in order to get an estimate of the amount of photobleaching and oxygen consumption. Based on the oxygen saturation signal, a fractionized irradiation can be introduced in order to allow for a re-oxygenation of the tissue.
© (2005) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Ann Johansson, Marcelo Soto Thompson, Thomas Johansson, Niels Bendsoe, Katarina Svanberg M.D., Sune Svanberg, and Stefan Andersson-Engels "System for integrated interstitial photodynamic therapy and dosimetric monitoring", Proc. SPIE 5689, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XIV, (8 April 2005);

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