Evaluation of gamma analysis results of IMRT and VMAT plans using simultaneous integrated boost technique for head and neck carcinoma

One of the preferred treatment methods in head and neck cancer is radiotherapy. The aim of this study was to evaluate the doses received by critical organs by IMRT and VMAT treatment modalities using dose volume histograms and to examine the Quality Assurance measurements of these two treatment modalities. In the first part of the study, 7 fields of IMRT and VMAT with planar and coplanar 3 double arcs were planned with Eclipse® TPS for 17 patients diagnosed with head and neck cancer. The IMRT and VMAT techniques were applied in combination with the Simultaneous Integrated Boost dose method in order to apply different dose schemes in a same fraction. Different doses were prescribed to highrisk lymph nodes and low-risk lymph nodes, and treatment plans were normalized so that the Planning Target Volume received 95% of this dose. The dose received by each critical organ in the treatment area according to the critical organ dose limitations determined by the RTOG was checked on the DVH during the treatment planning phase. Dose values were recorded and analyzed statistically. As a result of IMRT and VMAT planning, it was concluded that there was no statistically significant difference in the OAR dose limits of both treatment techniques, except for the left optic nerve (p>0.05). It was observed that the IMRT method was more advantageous than VMAT, especially in the orbital region. For the rest of the critical organ evaluation, it was concluded that one of the two techniques can be preferred according to clinical conditions. In the second part of the study, gamma analysis evaluation was performed to verify the accuracy of IMRT and VMAT plans using global criteria of 3% DD and 3 mm DTA. Plans with a gamma pass rate of 95% passed the acceptance test. Keywords: EPID, Gamma Analysis, IMRT,SIB, VMAT.