Verification of Head and Neck External Beam Irradiation in Radiation Therapy

Abstract

The role of verification is primarily to detect treatment delivery errors and secondly, to assess the suitability of the size of the margins planned around the clinical target volume that allow for the uncertainties in the radiotherapy process. This study that was performed in RICK including 57 patients, 30 of them were female represented (52.6%) and 27 were male represented (47.4%), aimd to verify the geometrical and dosemetric changes during external radiation therapy of brain, nasopharynx and maxillary antrum cancer. The data was collected from the patient’s records, simulation process and treatment by using master data sheet and simulator images in addition to treatment portal films. Using Interactive Data Language IDL software to measure the dimension and length of each axis for all images. Moreover, the results showed that the mean of simulator in X-axis 9.68±4.64 and for treatment film X-axis was 9.64±4.52, and for Y-axis for simulator 9±3.45 and for treatment film 8.96±3.25. Using paired sample t-test show there is no significant differences between simulator and treatment film for X-axis and between simulator and treatment film for Y-axis. The association between simulator and treatment film for X-axis was 0.96 mm/mm, and for Y-axis was 0.94 mm/mm. Linear regression results showed that the rate of association for the simulator (X-Axis) and Treatment film (X-Axis) increases by 0.313 mm, and the rate of association between simulator (Y-Axis) and Treatment film (Y-Axis) increases by 0.437 mm. A linear correlation was represented between treated and simulated collimator rotation, were the correlation was very strong according to R²=0.9998. In addition, another inverse relation was found between total dose and source collimator rotation, the TD is decreased by 0.063Gry pear each degree of the collimator.