الفهرس 
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Abstract
PDT is a local treatment modality, which in its nature has several potential benefits. The main advantage is the fact that PDT is comparably selective. There are two aspects behind this. One is that photosensitizers preferably accumulate in malignant tissue, and the other is the spatial confinement of the light irradiaiton to the vicinity of the malignant tumour. This thesis considers a non-thermal regimen of utilizing coherent and non-coherent light energy, in a natural way, to assess the effect of photodynamic therapy (PDT) in the treatment of solid malignant tumors. This thesis pays special attention to the use of Methylene Blue MB+ as the photosensitizing agent (Photosensitizer), Diode laser, and tungsten lamp as light sources. 200 mice (Albino mice) of average weight 25±5 gm with Ehrlich tumours transplanted in the hind limb were selected for the study. Animals were classified into two main groups’ laser and non-coherent light groups. Each group was subdivided into two groups according to the energy densities applied (laser 108 J/cm2 & 162 J/cm2 and non-coherent light 120 J/cm2 & 180 J/cm2), each sub group was reclassified into three groups according to the photosensitizer concentration. The PDT process assessment was done based on the different concentration of Methylene blue ’0.5% - 1% -2%”, light source either laser or non-coherent light and exposure time. Assessment was done as tumour size measurements, (tissue biopsies) histopathology examination, fluorescence imaging and photosensitizer spatial distribution and determine mg2+, ca2+ tissue content pre and post PDT. from the obtained results, we found that the photodynamic therapy using diode laser or non-coherent light as a light source with different energy densities and MB+ with different concentrations (0.5%, 1%, and 2%), showed that a significant reduction in tumour size p = 0.0001. But using non-coherent light and high MB+ concentration resulted in slightly more PDT effect reflected on tumour size reduction. The histopathological evaluation of the control specimens revealed subcutaneous infiltration with leucocytic inflammatory cells, which was followed deeply by confluent sheet of tumour cells. The examination among the group received Methylen blue only showed normal skin and intact skin appendages overlying tumour cells. It was difficult to draw any conclusions concerning histopatholoigical changes among the intervals of treatment (4, 8 days P.T), as well as between the different energy densities applied; while a histopathological difference could be observed between the laser and non-laser treated groups. For the treated groups received 0.5% MB, the examined treated tissues revealed three distinctive layers concerning the effect of laser or non-laser regimens, the most superficial layer, the middle layer and the deep one. For fluorescence, imaging and photosensitizer spatial distribution the results showed that fluorescence pattern obtained from normal tissue injected by methylene blue showed an equal green and red fluorescence pattern. While tumour tissue specimen without methylene blue (Control tumour tissue) showed a high red fluorescence distributed all over the pattern. High blue fluorescence images was resulted in fluorescence imaging captured just at the beginning of PDT process ”zero day post PDT”, at four days post PDT the fluorescence images detected showed that decreasing in the blue fluorescence, increasing in red and green fluorescence The fluorescence images obtained from eight days post PDT samples showed a highly increasing in green and red fluorescence. These patterns were obtained from all the treated groups with different (MB+) concentrations which reflect the spatial distribution and photobleaching of (MB+).For laser induced breakdown spectroscopy the results obtained showed that tissues specimens from each group were examined for Ca2+ and Mg2+ content using LIBS technique. The obtained spectra showed and emphasized that Ca2+ and Mg2+ content is higher in malignant tissues than normal tissues. The spectra obtained from the different tissues treated with PDT and different Methylene blue concentrations showed that the Ca2+ and Mg2+ content varied according to photosensitizer concentration and light exposure time. There was a difference in elemental spectra for the groups subjected to 10 min PDT protocol and groups subjected to 15 min PDT protocol. Calcium and Magnesium spectra shifted to normal tissue spectral line rather than malignant tissue spectral line. This shift was varied and cleared in 2% MB+ that exhibit more shift to normal tissue spectral line then 1% MB+ and at last 0.5% MB+ that showed least shifting behavior compared to the normal tissue. The light systems used to activate the photosensitizer gave rise to slight differences in their spectral lines. Diode laser system showed better results in respect to non-coherent light system.