Background: Patients undergoing Intensity Modulation Radiation Treatment (IMRT) for lung cancer were the focus of this research, which sought to compare the global gamma index with the local index.
Purpose: This study compares the local and global gamma indices for plans for lung cancer patients treated with the Intensity Modulation Radiotherapy Technique (IMRT).
Methods: A cross-sectional clinical research study was conducted at Al-Amal National Hospital for Radiotherapy and Nuclear Medicine in Baghdad from January to July 2024. The study involved 45 patients with unilateral lung cancer aged 40-70 years who were forwarded radiation therapy. Patients underwent a CT simulation for treatment planning via MONACO version 5.1 preparation. They were treated with a 6 MV or 10 MV X-ray photon beam from the agility linear accelerator manufactured by ELEKTA, with a gamma index criterion of 3%/3 mm.
Results: This study compares local and global gamma indices for two-dimensional gamma indices (2D) and three-dimensional gamma indices (3D). The results show that the global gamma index (%GP) passing rate is higher than the local gamma index for 2D and 3D. The three-dimensional gamma passing index is also greater than the two-dimensional gamma passing index. The analysis reveals a significant correlation between the number of segments and monitor units and the local and global gamma indices, with an inversely proportional relationship. This effect is also observed in the 3D gamma index.
Conclusions:The 3D global gamma index is more accurate than the 2D local gamma index. This finding indicates that Quality Assurance (QA) is necessary for complex treatments, such as IMRT, where high modulation is crucial for achieving therapeutic goals. Understanding this can optimize radiotherapy quality, particularly for techniques such as IMRT and Volumetric Modulated Arc Therapy (VMAT), which require a high degree of modulation for effective treatment.
International Journal of Radiology and Diagnostic Imaging
