Dosimetric Evaluation of Volumetric-modulated Arc Therapy versus Intensity-modulated Radiation Therapy in Prostate Cancer Radiotherapy: Enhancing Treatment Precision and Organ Sparing

A BSTRACT Aim: This study presents a comprehensive dosimetric comparison of volumetric-modulated arc therapy (VMAT) and Intensity-Modulated Radiation Therapy (IMRT) for localized prostate cancer, focusing on organ-at-risk (OAR) sparing and plan quality indices. Materials and Methods: This retrospective analysis was conducted in our hospital, between 2021 and 2023. Treatment plans for 50 prostate cancer patients were evaluated using computed tomography simulation data acquired with a 16-slice scanner at a 3.0 mm slice thickness. All patients were prescribed a total dose of 60 Gy, delivered in 20 fractions (3 Gy per fraction). Treatment planning was performed using 15 MV photon beams on a Varian CLINAC DHX linear accelerator. Each patient had VMAT and IMRT plans generated using the analytical anisotropic algorithm. Dose-volume histograms, irradiation volumes for OARs and dosimetric indices such as conformity index (CI), homogeneity index (HI), and gradient index (GI) were assessed. Statistical analysis using the paired t -tests was conducted. Results: VMAT demonstrated superior performance across all the parameters. The mean CI was 1.11 (VMAT) versus 1.23 (IMRT), HI was 0.09 versus 0.13, and GI was 3.8 versus 4.3 (all P < 0.05). VMAT significantly reduced V50 Gy and V30 Gy for the bladder and rectum. Statistically significant differences ( P < 0.05) were observed in all comparisons. Conclusion: VMAT significantly outperformed IMRT across all dosimetric indices, highlighting its superior ability to minimize the radiation tissue dose to critical organs while maintaining optimal tumor coverage.