Investigation of the effect of radiotherapy techniques on dose distribution in esophageal cancer treatment

In this thesis; The aim of this study was to compare the superiority of the target volume for three different devices and 4 different methods in terms of dose and critical organ doses in 15 treated patients with esophageal cancer. For the treatment, patients' who had already had computed tomography (CT) scans, virtual plans of 3-D Conformal Radiotherapy (3D-CRT), Intensity Modulated Radiotherapy (IMRT), Volumetric Modulated Arc Therapy (VMAT) and Helical Tomotherapy (HT) treatment methods were established. The dose volume histogram (DVH) and organs at risk (OAR) doses were compared. As a result of SPSS analysis, their superiority against each other was evaluated. For PTV, 180cGy per fraction was given in total, 5040cGy. 6MV beam was used for each planning. The prescribed dose was normalized to 95% for each plan. The evaluation of treatment volumes was based on ICRU 83 reports. For PTV; the most homogeneous dose distribution belongs to the IMRT technique. As a result of HI comparisons, 3D-CRT 0.84 ± 0.01; IMRT 0.57 ± 0.05; VMAT 0.06 ± 0.013; HT 0.08 ± 0.03 (p <0.001). The most uniform dose distribution belongs to VMAT technique. CI values are 3D-CRT 1,84 ± 0,2; IMRT 1,25 ± 0,05; VMAT 1.19 ± 0.04; HT 1.2 ± 0.06 (p <0.001). HT is the best technique for Target Coverage Index (TCI). 3D-CRT 1,85±0,23; IMRT 1,08±0,27; VMAT 1,08±0,05; HT 0,92±0,01 (p<0,001). IMRT is the best, for Uniformity Index (UI). 3D-CRT 1,07±0,01; IMRT 1,03±0,009; VMAT 1,04±0,009; HT 1,05±0,01 (p<0,001). For risky organs (OAR), The comparison of Spinal Cord data, its protection has been ensured in all techniques. For the comparison of lung data, VMAT and 3D-CRT techniques provided better protection than other techniques. The IMRT and VMAT techniques provided better protection for the comparison of heart data. VMAT, IMRT and HT techniques were provided for right and left coronary arteries. In the radiotherapy of esophageal cancer, while the data obtained from 4 different techniques are seen within the acceptance limits for all techniques, the best techniques for providing the dose prescribed to PTV are VMAT and IMRT techniques. In protecting healthy organs, all techniques are within the acceptance limits. Key Words: 3D-CRT, VMAT, IMRT, HT, Esophageal Cancer.