| Abstract [eng] |
During external beam radiotherapy of head and neck tumors is impossible to avoid unnecessary exposure for the healthy tissues and critical organs like spinal cord, oesophagus, brain stem and others. Therefore, the main task of radiation therapy is to protect healthy tissues and critical organs without exceeding the tolerance dose level and without reducing the maximum dose to the tumor in case of head and neck cancer and other localizations. In this work, three-dimensional (3D) modulated intensity radiotherapy treatment planning of head and neck tumors was performed. After analysis advantages and disadvantages of 3D Modulated Intensity Radiation Therapy for the head and neck tumors treatment, exposure to the critical organs planned by 3D IMRT methodology was evaluated by comparing irradiation dose values with tolerance dose levels (QUANTEC recommendations and Ontario H&N IMRT protocol), identifying the possible risks of early and late toxicities. Following a qualitative analysis of 3D IMRT plans, it was observed that even the risk of early and late toxicities of critical organs may be reduced, however for some critical organs such as salivary glands or oesophagus it was impossible to avoid exposure, which was higher than the recommended tolerance dose level. Therefore as a result for some patients have been experienced early and late toxicities such as xerostomia, dysphagia and even a decrease up to 25% in salivary gland function. Though early and late radiotherapy toxicities have been observed for the patients, evaluated indices of conformity and homogeneity for the 3D IMRT plans were close to 1, what means sufficient and guaranteed local control of the tumor. |
