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

Radyoterapi

Abstract

Definitive radiotherapy (RT) is the mainstay of treatment for locally advanced lung cancer (LALC). There are different RT techniques for LALC. In this study, Volumetric Arc Therapy (VMAT) and Helical Intensity Modulated RT (Hel-IMRT) were compared dosimetrically. For the study, 15 patients who received definitive RT with the diagnosis of LALC between 01.01.2022 and 01.04.2022 in the Radiation Oncology Clinic of Ankara City Hospital were evaluated retrospectively and dosimetrically. Simulation Computed Tomography (CT) images were obtained using the GE Discovery. Two plans were achieved for each patient: a Hel-IMRT plan with the Tomotherapy® H™ treatment planning system (TPS), and a VMAT plan with the Eclipse™ TPS.  The value of D 95% (95% of the target volume takes 95% of the prescribed dose) of PTV was intended to receive 5700cGy and above. Additionally, dose limitations have been complied with in critical organs by current guidelines. Using patient electronic system data and patient file information; disease stage, lateralization (right-left), location according to the carina (upper-lower), hot spot doses, gradient index (GI) and homogeneity index (HI), conformity index (CI), heart mean dose, esophageal mean and maximum dose (0.03cc), spinal cord max dose (0.03cc) were noted. The SPSS Package Program version 23.0 was used for data analysis. Non-parametric Wilcoxon-Signed Rank test was used for dependent two-group analysis. The statistical significance limit was £ 0.05. The value of D 95% was significantly higher in the Hel-YART technique than in VMAT (p=0.001). In terms of CI (p=0.001), more optimal values were found with the VMAT technique. There was no significant difference between HI (p=0.069) and GI (p=0.069) two techniques. In critical organs data; the spinal cord maximum dose was significantly lower in the Hel-YART technique (p=0.011). In the VMAT technique, lung V20 (p=0.002), lungV5 (p=0.01), mean lung dose (p=0.01) and mean heart dose (p=0.012) were significantly lower than Hel-YART.

There was no significant difference between the two techniques in terms of esophageal mean, esophageal maximum, and hot spot doses. There are different points where the two different techniques are superior. In the choice of treatment technique, patient-based choices are appropriate per the patient, disease, life expectancy, and clinical practice.