Radiotherapy of oncogynecological patients in the conditions of modern technologies
Summary. Introduction. Despite the intensive development of technology, significant progress in the development of new radiotherapy techniques in the last decade, the search for optimal models of contact radiation therapy, brachytherapy (BT) with high-dose sources (HDR — high dose rate — above 12 Gy/h) to improve chemoradiation treatment of gynecological diseases continues to be the subject of widespread debate. In this context, more in-depth research in the field of clinical radiobiology is needed, comparing the physical-dosimetric characteristics and biological effects of 192Ir with the effects of reference 60Co gamma radiation, given the difference in their energies. Materials and methods of research. We conducted a comprehensive conservative treatment of 94 oncogynecological patients stage II–III, T2–3N0–1M0, which depending on the method of BT were divided into 2 study groups (28 patients, 192Ir HDR BT and 30 patients — 60Co HDR) and the control group — 36 patients who underwent BT with sources of 60Co medium power (MDR — medium dose rate — 2 Gy/h-12 Gy/h). Total focal doses from the combined radiation therapy were up to 80–90 Gy per tumor center and 44–46 Gy per zone of regional metastasis, at a single focal dose — 1.8–2 Gy. BT was performed in the mode — 6 Gy 2 times a week. Some patients underwent radiobiological studies using peripheral blood lymphocyte test systems in oncogynecological patients and with subsequent metaphase analysis of spontaneous and radiation-induced chromosome aberrations. Results and discussion. Analysis of the direct results of the effectiveness of 60Co or 192Ir sources in HDR BT and dynamic monitoring data for 3 months showed that a positive tumor response (complete + partial regression) in gynecological patients in the study groups after chemotherapy increased by 20,1% and 16,6% compared with the use of 60Co MDR in BT. Toxic effects of treatment on the number and degree of their manifestations in the studied groups of patients did not differ from the control and did not exceed the second degree. The results of radiobiological studies correlated with clinical. There is a clear dose dependence of the frequency of induced chromosome aberrations and the specificity of radiation exposure (quadratic dose dependence of radiation marker induction) in lymphocytes of primary patients, which are the basic criteria for recognizing them as predictors of radiosensitivity of conditionally healthy cells that fall into the area of therapeutic exposure. Conclusions. High-energy modern BT technologies using 192Ir HDR and 60Co HDR sources in combination radiation therapy for gynecological patients, allow to concentrate in a short period of time high doses of ionizing radiation energy in a limited amount of tissue, which leads to increased risk or damage. High accuracy of pre-radiation training, correct planning using 192Ir HDR and 60Co HDR radiation sources makes it possible to significantly improve the immediate results of treatment of gynecological patients without increasing toxicity (general and local), the number and degree of possible early and late local radiation complications. The nature of the dose dependence of radiation markers will serve as a basic criterion for the recognition of dicentrics as cytogenetic predictors of increased radiosensitivity of non-malignant cells from the environment and tumor bed.Key words: HDR brachytherapy; MDR brachytherapy; sources of ionizing radiation 192Ir and 60Co.
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