Assessment of Dose Distribution and Organ-at-Risk Exposure in VMAT Versus 3D-CRT for Right Breast Cancer

Introduction: Breast cancer is one of the most common malignant tumors worldwide, and radiotherapy plays a crucial role in its treatment. This study compares Volumetric Modulated Arc Therapy (VMAT) and Three-Dimensional Conformal Radiotherapy (3D-CRT) for right-sided breast cancer treatment, focusing on dosimetric parameters.Material and Methods: This retrospective study included 20 patients with right breast cancer treated at the International Hospital of Khouribga (mean age 52.4 ± 4.9 years; mean body mass index (BMI) 27.2 ± 1.1 kg/m²). For each patient, two treatment plans were generated: VMAT with dual coplanar arc configuration and 3D-CRT with opposed tangential beams. Analyzed parameters included target volume coverage and doses to organs at risk. Results: VMAT provided superior target coverage and dose conformity. The mean homogeneity index (HI) was lower with VMAT (0.08 ± 0.02) than 3D-CRT (0.14 ± 0.02), and the conformity index (CI) was higher (0.99 ± 0.01 vs. 0.96 ± 0.02). Mean heart dose was 4.9 ± 0.7 Gray (Gy) with VMAT versus 1.0 ± 0.2 Gy with 3D-CRT; ipsilateral lung mean dose was 13.7 ± 1.5 Gy versus 11.9 ± 0.7 Gy, respectively. Contralateral organs received higher low-dose exposure with VMAT. VMAT achieved improved planning target volume (PTV) coverage and conformity, whereas 3D-CRT provided better contralateral organ sparing. Conclusion: This study demonstrates VMAT's dosimetric advantages over 3D-CRT for breast cancer treatment, providing institutional validation for technique selection in resource-limited settings.