ABSTRACT
Photodynamic therapy (PDT) is one of the expectable current cure operation methods. Tumor tissue is treated by abundant oxygen in a body and generated singlet or free radical from exterior laser diode and photosensitizer. Current problem of PDT is the low penetration power of the light beam in a deep seated large tumor and solid tumor thus results in low treatment outcome. In the study, we tried to develop interstitial photodynamics therapy treatment to solve this problem. As the accurate determination of light dosimetry in biological tissue is one of the most important factors affecting the effectiveness of PDT, parameters used in this study are the optical property of biological tissue. Since biological tissues have large scattering coefficient to visible light the penetration depth of a biological tissue in visible light region is only 15~20 mm. We showed that it is possible to measure fluence rate and penetration depth within the biological tissues by Monte Carlo simulation very well. Based on the MC simulation study, the effectiveness of interstitial photodynamic therapy on tumor control in solid tumor was proved through in vivo animal experiment.
Subject(s)
Animal Experimentation , Light , Oxygen , Photochemotherapy , Treatment OutcomeABSTRACT
BACKGROUND: Photodynamic therapy (PDT) of hepatic tumors has been restricted due to the preferential retention of photosensitizers in normal liver tissue. Therefore, superficial tumor illumination causes subsequential liver necrosis. Moreover, the limited light penetration during superficial illumination makes it impossible to treat deep-seated or larger solid tumors. These limitations were overcome by interstitial therapy. Aim: The aim of study is to investigate the macroscopic and microscopic effect of a single session of interstitial photodynamic therapy on liver tumor. METHODS: The Morris 7777 hepatoma cells were injected subcutaneously into the flanks of Buffalo female rats. Tumor growth was monitored with measuring the tumor size. Animals were pretreated with hematoporphyrin derivative 48 hours prior to the intratumoral delivery of laser radiation, when the tumor had reached a volume greater than 1.0 cm3. One or two weeks after interstitial PDT, the extent of tumor necrosis was evaluated microscopically. RESULTS: Volume of lesions averaged 10.2 mm3. Histologic stains demonstrated microvascular thrombosis and coagulative necrosis within the lesions. There appeared to be 100% cellular destruction within the lesion by cytochemical staining. CONCLUSION: The results of this study show the ability of interstitial PDT to cause destruction of liver tumor.