Radiodynamic and contact radiation therapy of inoculated tumor in an in vivo experiment

Introduction. In recent years, interest in the use of such physical factors as magnetic fields, ultrasound, and hyperthermia to activate Photosensibilizers (PS) has increased in experimental oncology. One of the promising scientific areas is radiodynamic therapy (RDT), a new method of therapy based on the combined use of PS and ionizing radiation [1]. The first PS with the radiosensitizing properties proven in the in vitro/in vivo experiments were 5-aminolevulinic acid, Hematoporphyrin, and Photofrin II [2, 3]. The main mechanisms of the implementation of the antitumor response of RDT remain poorly studied. According to Shaffer M. et al., on the one hand, PS (for example, "Photofrin II"), under the influence of ionizing radiation, can enhance the radiolytic effect due to reactive oxygen species (hydroxyl radical, superoxide anion and singlet oxygen) formed in the tumor cell upon exposure to the proper radiation [2]. On the other hand, the exposure to ionizing radiation leads to sublethal and lethal damage to tumor cells. Further, sublethal changes are, as a rule, reversible, associated with the implementation of the mechanisms responsible for restoring the functions of the tumor cell. In case of activation of the PS "Photofrin II"