Comparison of Volumetric Arc Therapy (VMAT) and Helical Intensity Modulated Radiotherapy (Hel-IMRT) in Lung Cancer Radiotherapy

Aim: Definitive radiotherapy is significant in the treatment of locallyadvanced lung cancer. Various radiotherapy techniques have beendeveloped to preserve critical organ doses while providing better dosecoverage to improve the therapeutic index. The aim of this study wasto evaluate the differences between VMAT and Hel-IMRT techniques inthe treatment of locally advanced lung cancer.Material and Method:This study was planned to use VMAT and Hel-IMRT techniques with simulation computed tomography data of 15patients who underwent definitive chemoradiotherapy for locallyadvanced lung cancer between 01.01.2022 and 01.04.2022. It wasplanned to compare two different radiotherapy techniques in whichcontinuous irradiation was performed circularly in the treatment oflung cancer. The same user created the plans according to the samedose limitation goal. Target volume coverage and critical organ dosesof the patients were recorded.Results: In the Hel-IMRT technique, the D 95% value for target volumedose coverage was found to be significantly higher (p=0.001). Interms of CI (p=0.001), more optimal values were found with the VMATtechnique. There was no significant difference between the twotechniques for HI (p=0. 916) and GI (p=0.069).In the data obtained forcritical organs, the maximum dose to the spinal cord was found to bestatistically significantly lower in the Hel-IMRT technique (p=0.011), thelung dose parameters (V20, V5 and mean dose) in the VMAT technique(p=0.002, p=0.01, p=0.01), and the heart mean dose was lower in theVMAT technique (p=0.002, p=0.01, p=0.01) and the mean heart dosewas found to be lower (p=0.012). There is no significant differencebetween the two techniques for esophageal mean dose and hot spotdose in the plan.Conclusion: There are different points at which the two differenttechniques are superior to each other. For this reason, the choice oftechniques in treatment planning should be based on patient andclinical factors.