Dosimetric comparison of three dimentional conformal radiotherapy, intensity modulated radiotherapy and hybrid intensity modulated radiotherapy planning techniques in esophageal cancer

Objective: The purpose of the study is to compare 3-dimensional conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT) and hybrid IMRT (h-IMRT) techniques from the aspect of target volume coverage, critical organ preservations. The evaluation of routine applicability of h-IMRT technique in esophageal cancers is also aim of this study. Method: In this study, 14 patients with diagnosis of esophageal cancer are included. A total of 42 treatment plans were designed for each patient with 3D-CRT, IMRT and h-IMRT techniques. In h-IMRT technique the 2/3 of 60 Gy defined dose was planned with 3D-CRT technique and the remaining 1/3 part was planned with IMRT technique using treatment planning system (TPS). The results of all treatment plans related to the dosimetric parameters of the target volumes and the critical organs were statistically evaluated. In addition, MU values and treatment durations were compared for each technique. For all plans, the volume value of the 30 Gy dose for all healthy tissue was analyzed. For the quality control of the dose distributions calculated by TPS, 2-dimensional dose distributions and point absolute doses were measured with MartiXX and ion chamber respectively. Results: In all regions of the esophagus, IMRT technique was found to be more successful than the 3D-CRT and h-IMRT techniques in terms of PTV. HI was in accepted limits for all techniques but, IMRT and h-IMRT techniques were beter for CI. As expected, treatment duration and MU parameters were found to be high in IMRT technique, but these parameters are considered as more advantageous for h-IMRT in clinical practice. Conclusion: In the radiotherapy of esophageal cancers, the dosimetric comparison of different planning techniques did not show a significant difference in terms of PTV, OAR and HI-CI indices but from the aspect of MU, h-IMRT technique was been recommended as an option. Key words: Hybrid IMRT, Esophageal Cancer, Radiotherapy